Bike Motor Performance Tips

bicycle motors australia
ABN: 13107397740

3061 Quay South Dr. Carrara
QLD 4211
Mobile 0420 660 866

Z Box

bicycle engine

Phone us for assistance: 0420 660 866


A very useful website is - it's full of information shared by other motorised bike enthusiasts from all over the world.

Click here for MotoredBikes

another good site is


from Geoff Tonta - 16 May 2011

I have put a 49cc motor in a $5 tip shop bike, all going well.

My wife recently purchased a cycle, that had a sprung seat post.  I inquired and found a shop with a range of sprung posts, and paid $25 for a suitable unit.  They were $20 - $40, but there is a wide range of sizes, so take your old post when you go to purchase.  Slight problem is that the seat is now a little higher than I like, but the ride is certainly smoother, esp. on gravel.

I have a sprung Brooks seat, (from the tip shop), and with the sprung post, it is a featherbed.


I was hoping you would load this on to your site for other builders who want performance out of the bikes. I think its a good guide with loads of help for your custmers. Thankyou

A Big Boy Bike Builders Guide.

A bit about myself I have no licence so I ride my Zbox 66cc daily and sometimes a hole heap ok kms in a day. I have been a motorised bike rider since high school 15 years ago  when I picked up a second hand Sachs Bike(Well built but very slow compared to Zbox. About 15 years ago then followed by two 30cc Chinese imports.  Very bad build compared to Zbox and nothing on speed of Zbox. Zbox are the best built motor I have seen for a bike.I am writing this to try and put a fair bit of good info in one spot because the info is out there but very spred out.


I purchased my ZBox 66cc from Stephen about 6 months ago. Quick delivery. Everything you need is in there except lock tight but you can order that to. 

 One thing I didn't get was the big frame adaptor, when I did order one later he sent it free.


First thing to do is take all you engine studs all your nuts that go on them, and any others you want to never break to you local nut and bolt shop and get them all replaced for high tensile steel studs. You don't want these to break of in the engine, trust me it happened to two of my studs. (cost $60.00 to have engineer remove. Almost had to by new motor but relocated holes. Get lock nuts for all your 10mm nuts.(guy at nut shop  will know what I mean if you don't. Plus you can get your lock tight when your there.(vital to have.) Get spares while you are there you will need them one day. also use split washers on every thing you can. I Also changed allot of my nuts and screws for Allen key or hex head. means I carry less tools in back pack. I also changed chain tensioner bolts that hold it to the frame for high tensile.( never comes loose)


Take your time with your rear wheel choise. If your gunna be rough and jump gutters you will break spokes and there not fun to change all the time. There are some purpose built with a rear drum brakes plus cogs on both sides.  They are the best I've seen but expensive , but so is a high quality rear rim,spokes,and hub. so you decide which way to go. try and get one with high pressure tire. Im 90kgs and find im always pumping up my tire. Slicks are great rather than mtn bike style. you don't want come of in the rain at the shops.I went for front shocks as well. it helps you braking heaps.


Other set up tips.

Don't mount your coil so the lead is tight or close to tight. will snap at coil end.

Watch what gear selectors you use. the less room the take up the better. (Unless you go all out with jackshaft kit.)

Run you bike in. (Dont cut corners here!) Then you can think about performance.

If you think your bike sounds like its piston is slapping around don't worry to much

its normal. check out you tube for a sound comparison. listen at idel revs hear the slapping.(this bike is a little hotted up so your bike wont sound like this at revs.



Ok now you bikes run in there is allot you can do to you bike to get you bike flying. You should be getting about 35km to 40kmh depending on your bike, mine was just off powerband at this stage.You might not think it but I've seen a few bikes on YouTube that do over 60kmh.  

one that runs on Ethanol that dose about 100kmh from memory. So you can do allot to them. You tube is a great help there are loads of videos on there to help us. These bikes are very popular in the U.S.


Spark plug and cap and lead replace them with high quality gear and motor bike shop can help ya, get a hotter plug. No point in putting in fuel if your not gunna burn it all.while your there check out anti vibration hand grips.


Fuel and carby, Make sure you tank is full for tuning. make sure you fuel filter is clean. unscrew fuel tap, filter in the tank (keep clean). When your bike is going flat out make sure fuel is going from to the carby cause they can suck the line dry when they get going.(blocked filter). I have changed my fuel jet for the larger one and had no success or power increase. Had more luck with moving float level, but still starved for fuel. So I got a dremel and bored out my air intake. nothing again still starving at high revs. So I don't suggest touching your carby unless you pretty switched on and confident. I suggest buying yourself a new carby high performance that is specially made for these bikes.(some have fuel mix screw that helps with tuning more adjustment means you can tweak your performance) Ask Stephen what he and his builders can get you. If not check out the U.S. market. Also there is high flow air filters you can get while your at it, they recon they sound great. Check out


Exhaust I have cut down the baffles and freed the ports with next size up holes in ya drill kit like suggested to me from another zbox builder. find in Stephens zbox tips. a bit more power and noise at the start but had not installed new carby yet. Do this one if you want more from your motor. Other than that you can buy purpose built high performance exhausts and expansion chambers if you want a wicked looking and sounding bike. Im sure you need a wide crank kit for that. So ask Stephen and his builders again what they can do for ya. there are lots of parts and providers out there so do your shopping online and you will find bargains.


Boost bottle. Ok I thought this was Nos the first time I saw its not. Its is a bottle that looks like a little Nos bottle. Its a air canister that should be 750cc from memory for a  66cc. It has a tube from you intake after your carby to the bottle. That aids in perfecting you air/fuel mix. You can check them out on you tube. Im not sure really how it work but as you will see on you tube. this is a WICKED MOD. you can build this your self as it is very simple guides on you tube.


By now your bike should sound like a weapon. Easley hitting powerband at a flick of the throttle.  Other than running these on ethanol there is one more thing you can do to really boost your bikes top end speed and easy no pedalling starts. This is called a Jack shaft kit. and it gives your bike gears. you can get these from Stephen or the U.S. Ok this is gunna cost ya heaps. maybe more than the original kit. So if your still interested you like your bike and speed. The jack shaft kit transfers the drive from the left side of your bike to the right and uses the bike original chain and rear derailer. So you can drop the clutch take of in 1st easily and you ride it like a motor bike changing gears to go up hills or for flat out speed. plus its easy to muck with you rear cogs to get more of what you want speed or hill climbing. no more peddling.


You can also increase compression by removing head gasket and replacing with thinner gasket, heard one guy made one out of a beer can. Check out Youtube for info on that.


Other tips.-get a Speedo to check how your mods help ya-  or look at   for heaps of vids and help and - Do you home work before mods so you don't waste money when you have to replace a part- Ride with tools if your gunna ride hard. mine are 1x,med shifter,med Phillips head screw driver,med flat head screwdriver, 10mm 12mm 14mm ring spanners. and a small Allen key set, role of tape.- Keep a good eye on nut and bolt tension, laziness here will cost you money-lock tight every thing you want to stay on your bike, pulss you can burr all stud heads so nuts wont ever come off, do this after install of engine-Don't buzz the cops at the lights doing 60kph they will do ya for speeding and it ruins it for the rest of us-now your bikes a weapon respect it take care of it or it will take care of you at high speed-buy lights and keep your reflectors and bell on ya bike so you dont get a nasty cop that fines ya for that- 

Enjoy your new high speed bike but be careful. Things are gunna come up on you a lot faster now so be ready.



Fitting engine to thick frame tubing

The bicycle I had at my disposal was had 28.5mm tube on the back and top of the frame triangle, and a 35mm tube on the front.
The studs on the front of the motor would not go over the front tube and the obviously the profile of the 35mm tube was wrong for the mount.

I tackled this by making up a pair of 100mm by 20mm square tube clamps, driven by two 100mm by 7.2mm bolts, passing through each end of the clamps.


The motor was placed inside the frame, and at the height expected if it was to clamp directly onto the frame on both front and back tubes,


but with the motor alongside the front tube, rather than over it.  Two pieces of masking tape were placed above and below the region where the front mount was going sit.


The motor was removed and the clamp put in place with two people winding the tension up on either end of the clamp as equally as possible.  A micrometer was used at the final stages to measure the distance the clamps were apart at either end to make sure the "squeeze" was parallel and we did not over do it.


All we had to do was squash the tube in about 3mm either side, this was not a problem and the whole thing went smoothly.  The bonus was the new profile (front and back) of the tube much more closely matched the required 28-29mm OD profile and allowed a snug fit with the motor. The studs were a close fit but pulled up quite well.

Main benefit was no drilling of holes in structural members of the bike and strength retained in the right profile of the tube, ie front to back.

To give an overall feel for the project here is a photo of the assembled machine.


Feel free to use this idea in your hints sheet if you feel this approach is OK, and would help others.

Rob Ward 2010.

Huffy Computer

The unit is a huffy 9 function bike computer and the problem was it would lose its mind every time I started the engine.
Solution is simple. A new, quality HT lead.
I used a Bosch, inductive shield part from the local auto discounters, $5.

First, cut off the distributor cap end.
You will also need to strip about 15 mm of the outer jacket to fit into the CDI connection.
Be very careful when you cut the end, that you do not allow the wire end from the inductive shield to contact the inner ignition lead.
Trim off this fine wire close to the insulation.
Firmly screw the lead into the CDI connector.
Some waterproofing is in order here. I use a product called Starbrite liquid electrical tape, available from Jaycar Electronics, Aus-wide (and NZ)
Seal the lead into the CDI with 2-3 coats of this.
Bear in mind that most auto HT leads require the nipple to be on the plug, unlike the original connector.

Hope this might help other users.
Best regards, Lin - Rockingham October 2009.

HT Lead

A good customer named Ben rang me and said he has replaced the spark plug cap with an NGK cap ($10) from his local go-kart shop. He also shortened the HT lead whilst replacing the cap and has now reported an enormous power boost - maybe worth a try for increased performance! January 2009


I have a feeling that the Bi-tron will work better and better as time goes on and the stuff penetrates all the bearings.

The engine seems far less sensitive to changes in the float and clip settings with the conditioner and Oil added. If I change it to a too rich setting the engine still idles fine and runs better that it used to at the same setting same at lean settings the idle does not race nearly as fast, I think maybe the bi-tron coating the metal of the carb, component allows the fuel to flow better perhaps in the ports as well acting as if I had polished them. I am running it with a higher float now on the leanest clip setting so that the engine runs richer at idle to keep the lube up.

One more tip: People have discovered that the piston skirt facing the inlet port partially covers the port during transfer. This can be safely filed away in a shallow arc and seems to work very well. Just maybe this could be done easily at the factory and would give your engines a safe and guaranteed edge over the competition. Not that you need one! I am going to try this when I find the time. It seems like a far less risky mod than messing with port modifications. Might be worth contacting the factory on this one

A final note, I ran my engine without the bottom gasket using Silicon sealant and I had an immediate boost in performance. I assumed this was because of the 1/2mm or so lost thus boosting compression. Now The silicone kept breaking its seal so I returned to using your gaskets which predictably resulted in the loss of this gain. So I removed the head gasket and honed both surfaces to a perfectly smooth finish. This should have restored the compression boost and it has given back some of the performance boost as before BUT not all of it ( The head is not leaking as far as I can tell). I realise now that they are not equivalent because losing the bottom gasket also changes the port timing, for the better it seems from my results. So as a safer and easier mod than losing the head gasket I will add a tip for losing the bottom one. I need to find a better silicone than the one I am currently using.

-Rohan Lorange

Hi Warren

Maybe you could add this to your info submissions.

I found no problems in assembling the Z80 kit and read with interest all the tips from builders on your web site and agree that some minor modifications need to be made to improve performance, all of which have minimal effect until the motor loosens up a little, so I will list what I found to be effective and thank those that have contributed before.

1    16 :1 Oil on run in is important
2    Grease in clutch housing and under engine clutch cable mount to lubricate drive shaft.
3    Idler wheel mount needs to be twisted a little as the rear fork extends at a slight angle.
4    Idler wheel will benefit from a thin washer between the wheel and the bracket, still allowing the flat faces to gip in the adjustment slot, the wheel will run freely with this.
5    Starving for fuel at higher revs, raise the carby float level by gently bending the shut off valve forks to set level higher. ( no need for larger jet )
6    Throw away the spark plug!!!!!! BOSCH WR 7AC set at .8 mm ( this may vary so play with the setting till its right as there is no other way to set ignition timing )
7    Cut the inner exhaust pipe to let it breathe a bit.  ( my extension is made from Hydraulic tubing and has cut the noise down significantly )
8    I can recommend the 700D touring tyre for the drivewheel as on my 27 inch setup, much more comfortable and more robust.
9    Get a rear view mirror if you're going to mix it with the traffic. 

End result : Easy start, hits powerband at 46kmph and all hell breaks loose, climbs hills that a Honda 50 scooter can't, will take off without pedal assist and cruises easily.

Karl Sass - 5 July 2008
karl's zbox
Karl's ZBox - 2008


After owning a 48cc engine for three years I upgraded to the larger Zbox 70cc engine. I have made a few simple modifications that have made a world of difference to the performance using basic tools.

All of the components which come with this engine kit are the same for both the smaller 48 and the larger 70. Having owned both I realised fairly quickly that the  components crucial to performance (the Muffler and the Carburettor) are optimised for the 48cc and not the 70. I always felt that there was just not enough flow through the muffler to accomodate the larger volume of exhaust gases produced by the larger engine. To remedy this I did two things:

#1 Let some exhaust escape through the screw that holds the end-cap of the muffler in place.

To do this I filed out the screw hole in the end cap by 1/2mm (Not too much). Then I wrapped some med gauge tie wire around the bolt and cut it with wire cutters to create a washer which was just over a full circle, enough to not fall off the bolt shaft yet providing a gap 5mm long matching up with the enlarged hole on the base cap. A normal washer is screwed over the top.

Make sure this gap is positioned so that the gases and oil are deflected away from the bike. This escape hole tiny though it is lets enough exhaust out for a noticable improvement.

#2 Improve flow inside exhaust pipe.

To do this I filed the holes larger on the first muffler baffle. (A drill would be better but I don't have one). You could also add extra holes too. The two holes that come on both baffles restricts flow too much. Only 1 extra hole the same size or the enlargement of the exiting holes is needed, remember these engines are surprisingly well tuned and we don't want too big a loss of back pressure.

The second mod is to cut off about 4cm off the internal end of the tail pipe ( the end furthest inside the muffler) This bypasses the 2nd internal baffle altogether. This mod will increase the noise of the engine considerably but is worth it.

#3 Improve fuel flow in the Carby.

Pull apart your carby and inside the float chamber you will  see the fuel needle. It isn't obvious but the small hex nut at the tip with the tiny needle hole unscrews. I replaced this jet with a Dellorto PHVB jet of size 76 which is larger than the stock. This increases the fuel flow at full throttle but has less effect at lower revs. I always felt that the 70cc was starved of fuel at full throttle. This will fix this. I have not tried larger jets but the 76 seems about right.

Phone ZBox to order a jet kit and instructions

#4 improve air flow through the carby.

By far the most noticeable Mod. Simply pull apart your carby removing all screws and valves. You are left with main body of the carby, we want to enlarge the main inlet cylinder which can be done using a round metal file and sandpaper wrapped around the round file rod. I enlarged the main throat of the carby by under 1mm all the way around and expereinced an amazing improvement in throttle response and engine smoothness. This Mod is so easy and works so well. Finish with sandpaper and wash all filings of thoughrougly. Magic!

-Rohan Lorange, June 2008

How to set the clutch or adjust for a worn clutch.
from Mark Collaros - January 2008

Before we get started make sure you are confident with your mechanical skills and understand that an incorrectly adjusted clutch can cause your bike to keep going even if you pull the clutch in. If you fall off your bike because it didn’t stop, and break both your legs, don’t come running to me. (Boom boom)

If you would like to adjust how the clutch works to give you either more or less slip, or if you want to tighten the clutch when it begins to wear out, it can be easily done by adjusting the special ‘T’ nut inside the transmission cover.

First remove the 5 screws and the transmission cover:

clutch cover

Then loosen and remove the locking screw which ensures the T nut doesn’t undo by itself:

clutch screw

You can see how the clutch works now - pull the clutch lever by hand or by cable and you will see the ‘driven plate’ move slightly away from the large transmission gear.

clutch plate

If you just want to adjust the clutch now, with the clutch lever still pulled tighten the T nut by hand all the way in then back it off ½ to 1 turn (as a guide) or as much as you like. By having the T nut very tight the clutch should never release and the small driving sprocket on the other side (where the clutch lever is) will never run free. Loosen it to suit your riding style, barely loose will release the clutch suddenly near the beginning of the clutch cable travel, and slightly more loose will give you more clutch slip enabling you to ease the clutch in or out. If you are nosey like me you should probably take it all apart anyway - the following pictures may help if you are not familiar with how a clutch plate works. Before you go ahead, remember not to get grease from your hands on the clutch material inside, or you will probably need a new clutch if it soaks in.

You can see that the spring pushes the driven plate away from the clutch material, so if the T nut is loosened all the way, the spring stops the friction material grabbing the driven plate. If you pull the clutch lever now, you will see the small thread in the centre go in and out. This is where the T nut grabs on to and sets the FURTHEST the driven plate can go. Now you should see that when the clutch lever is pulled in all the way, a gap is created between the driven plate and clutch material, so they do not grab anymore, and the small sprocket on the other side spins free. This small sprocket is part of the shaft with 3 studs you can see below – spin them and you will see the sprocket spin. It is these 3 studs that grab the driven plate.

clutch operation

So now put the spring and the driven plate back, and screw the T nut in and adjust it as to what you have read above.


With the clutch lever pulled in, tighten the T nut all the way by hand then unscrew it half a turn. Release the clutch, make sure the driving sprocket on the other side grabs, then pull the lever in and make sure it rolls free. This is a basic starting point, as you are more familiar with the clutch operation and your riding style you can set it to suit.

Finally, replace the locking screw and put the cover on. It’s a good time to make sure there is enough grease still on the transmission. Now check the clutch operation on your bike with the engine OFF. Make sure it works like it’s supposed to!


handmade sprocket

I rode my bike to work a couple of times but found that the trip was a bit long (36 km each way) leaving me a little bit too long in the saddle. I have done the exhaust modification and with the little bit of extra power from that, I felt the motor could probably handle a smaller sprocket on the rear wheel. I hoped that by doing this I could increase my cruising speed and reduce my time in the saddle! I had a sprocket (36 tooth) machined by Mike Sully who runs Kart Hire Australia (W.A.) and after the usual installation dramas (running without tensioner at present) have fitted this. It works perfectly and has increased my cruising speed by approx 8 kms. Against a strong wind or up a reasonable hill I pedal to keep things moving, but it’s a good feeling pedaling lightly in the bikes top gear! Note * When passing pedestrians on the bike paths I always tone it down, sound the bell and roll past – don’t want to give motorized bikes a bad name!

Nick Deane W.A. 2008

Very knowledgeable comment from Jeff December 2007

On this site there is an expansion chamber design program - freeware MOTA Two Stroke Engine Simulation Software  Here is a site with an exhaust design program for free. The exhaust open degrees is a fudge because this engine is not a race engine (only permits 105), but a few calcs in the other direction will help you get a near solution by guesstimating. Do not use GP racer factors or the motor will be so gutless at low revs it will not reach any peak power or high revs, use Enduro factors or then some. Aim for say 6000rpm should be OK and usable. If you insert the stinger (tailpipe) into the chamber a little (say 40mm) there is no real power loss and the noise will be less. If you insulate wrap the pipe to retain heat the power band will be 1500rpm higher, but the engine will wear a lot quicker if not seize.  Use a B7HS or even a B8HS when fitting a performance pipe and you may lose some engine life if thrashed all the time at full speed. The pipe design is best if it compliments the motor rather than stressing it. 

If you can tune a carby, start with a carby off a recent Jap 50cc scooter with an idle circuit from the scooter wreckers and a reed block with a short manifold machined to fit the barrel if you really want a jump in torque. 

When tuning the carby, tighten it to manifold a few times or at least check often and silastic seal cable into cap, as this air leak can lean out the motor and make it impossible to tune or idle. 

One of the best chain lubes is an industrial chain lubricant called "DriGraph". It is used for chains in industry where maintenance is low and wear and tear is high and 24/7. You spray sprockets when oil free, ditto for chain (a good quality chain) then occasionally oil with cycle lube teflon "Ice" wax. The chain will always wear a bit quicker than desired because the minimum front sprocket size should preferably be greater than 13, with either the front or rear sprocket being a prime number. (A small sprocket makes the chain go through a large angle and wears it quicker). Inverting the chain to even wear (turn inside out and or reverse direction) can extend use, but needs to be done very frequently to even wear with sprockets. 

The Zbox requires gentle running for a long time because the rings are made to last a very long time, (keep it cool by not overworking it) so that the rings bed very well. If you want, pull it down after a 1000km and lightly re-hone the bore to remove all/any high spots, especially around exhaust and stud locations. Be guarded from over tightening the barrel, as micro bore distortion can happen near barrel studs when barrel is expanded and running hot.  

I ran in the clutch gear for say 200km then graphited and very lightly greased, so that the high spots were already worn off before I greased it.  

The ignition cover is not machined flat and may let rain in, so remove it, file off high spots, gasket goo (Stag plumber's cement) all around except bottom edge to permit breathing and to be a drain before ignition magnets rust. Similarly some silastic on all rain exposed electrical connectors and spark plug lead will avoid breakdown in the first puddle. An earth wire from magneto earth to coil earth to head can be a big improvement some times where earths are corroded or weak or on painted surfaces. 

It is a very durable well made engine design, detuned for reliability and extended life and I am amazed at the low speed torque for a 50cc two stroke with such a small flywheel. The domed head contributes to this, as does the curved exhaust and inlet ports and it should not be considered a high speed engine or racing engine. 

Usually on a two stroke the rings should be renewed after a long life as the rings take up the piston slap at high temp and eventually (say 8000km) become a little oval from high temperature wear at exhaust port. The light hone removes any high spots near exhaust and will extend ring life and increase power and any reduce the chance of brittle ring fatigue weakening. 

If you do not intend riding the thing for a few months, turn off petrol and burn carby empty before laying up to avoid a float bowl and fuel tank full of oil months later. Also keep tank full to avoid condensation of water into the fuel, which incidentally reduces fuel tank petrol evaporation because of reduced surface area of fluid.The main problem with little motors is dirt and water in the fuel jets and stale fuel. Add a clear fuel filter to fuel line or put a loop in a clear fuel line so you can see dirt and water before it stops the motor. Unleaded fuel is "stale" after two months and you will notice the difference with fresh fuel. 

Always carry a spare plug and plug spanner if going long distances!!!  




from John Mann of Motrax NZ

The biggest performance boost will be to remove the baffle from the exhaust pipe and then drill 2 small holes in the long skinny pipe about 40mm  from the end closest to the outlet. This will increase the noise level , but the horsepower increase will be dramatic!!! For max horse power increase, simple cut the pipe about an inch to 50mm from the outlet and then replace. Or. Drill one hole, replace and then ride and see how much noise is increased vs. power gained. You can then drill another hole to increase the power and, as you do, decide if you have enough power Vs the increase in noise. I simply cut my pipe off about an 25mm or so from the outlet end. It is  louder but the horsepower increase is awesome!!!

Remove the screw from the end of the muffler and withdraw the cap and tube


For more performance (and more noise) drill more holes. 


For top performance  cut the tube off leaving 50mm


From David Walter of Muswellbrook - 2007 New idea for locating fuel tank:

david walter bike
By the way, just as a piece of trivia for you, when fitting my Zbox kit,
I found my long legs hit against the fuel tank. So I have fabricated a
bracket that comes off the seat pole base (in the triangle section where
the reflectors normally sit), and have fitted the fuel tank backwards
(valve facing forward) onto the bracket sitting above the rear wheel.
Works a treat. I don't smell petrol, my legs don't hit the tank, and it
doesn't look that bad.

From Julian August 2007:

Hi Warren

For your readers I have some new tips.
After some research I found the best spark plug is NGK B6HS or if you need a hotter plug, the B5HS. Having said that, if your spark plug is the colour of ash/grey all is ok, but if it is black check your spark plug lead and if ok use the hotter plug (B5HS)
I have made my own carbon lead the same as a car lead.
My engine has done approx 5000km and no problems with the motor BUT to do that I use VALVOLINE RACING TWO STROKE OIL, the oil go-carts use, and mix it at 20-1 - great stuff and cheap $30.00 for 5 litres from the depot.
I replaced the chain with an all Japanese chain from the push bike shop, had to buy two as there were not enough links
(4 links to short) and it is gold in colour which makes the bike look great (YBN 415 MOTORCYCLE CHAIN) $10.00 per chain and excellent quality.
I also changed the way of lubricating the chain, oils make a mess of the back rim etc etc.
I bought a container or PARAFIN WAX from the hardware store 200ml
In an old pan that is big enough to roll the chain in I emptied a large can of CRC TAC2 which is a very sticky oil, added two table spoons of cv joint grease and placed the paraffin wax in the pan.
1)   In another larger pan I put water in it so when both pans are inside each other the water will not overflow
2)   I lit up a small barbecue, placed both pans over the burners and gradually the water started to boil. The wax started melting and mixing with the sticky oil, so as this happens reduce the heat and stir the grease till it does not exist. Turn the heat off and let it solidify to wax again. When you touch the wax it should feel a little slippery and oily and it's ok.
4) Wash the chain down well with petrol a few times, wipe down with a rag so it does not drip.
5) Roll chain and at one end put a wire through the link and place it on top of the waxy lubricant, as the temperature of the water starts to boil reduce heat and slowly the chain will sink to the bottom of the pan, leave it for 2 minutes.
6) Slowly take the pot to a place where the chain can be removed with the wire that is attached to link. Hang it up to drip dry 20min as the chain will be HOT.
7) Final result is perfect as it's all lubricated and waxed so no dust will stick. It also doesn't make a mess of your bike, and is good for 200 kms or so.
I also made a new idler gear as my tensioner:
- I bought a bmx free wheel sprocket, removed the ratchets inside so it freewheels back and forward and greased the bearings, about 60 of them (30 each side).
- I grounded the sprocket teeth down to get a smooth rolling effect.
- Made a male thread to suit the sprocket with a drill hole in the centre and new pin.
Then, once the chain located the spot where the sprocket was going to be, I loctited the pin so that the sprocket revolves on it's own 60 bearings, and the chain runs so smooth - best thing I ever did.
Lubricating the normal bike chain and what to use?
The best kept secret is (AUTOMATIC GEARBOX OIL) dextron lll. What's so good about it? It's cheap and any mechanic
will give you a bit to last you 12 months, it's full synthetic oil, excellent lubricating properties. I've found no bike oil is this good and I'm sure if you try it, you will never use bike oil again.

I've also attached some photos, so hopefully it can help someone else as well.

Regards Julian

julian chain
julian chain 2
julian preparation
julian wax

From Aaron of Victoria Park WA - April 2007

Warren,  Just to further update you from last week, below are the pictures of my mountain bike with the Zbox engine attached.  So far I've only done 17km with it but the motor appears to be loosening up.  One problem I'm having with it is the engine just won't run without half choke, though I'm guessing this may improve as the engine wears in a bit more.  The mixture screw is at about 4 turns out from the seating position, and I'm using hi-octane unleaded at a ratio of 15:1.  Once I had the right bike, it took about a day to get it together.

aaron bike 1
aaron bike 2

The bike actually isn't the one I initially set out to use, this one was obtained from an Op Shop for $25 and the only mods I've done to it apart from your kit is put the speedo on it and air in the tyres.  The original bike (black and red one below) that I intended to use created so many problems that it wasn't going to be worth it, and it may be useful to place some of the things I found on your website as a guide to others.

The original bike had clearance problems with both the spark plug and the carby such that the motor couldn't have both on at the same time.  The problem stems from the cross bar on the latest batch of chinese cheapie mountain bikes that are available from K-Mart & Big W.  The physical length of the seat post between the front bar and the cross bar is down to 320mm which is just too short.  Two bikes I've now seen this on are the Cyclops Maximal (one I was intending using - Kmart) and the Dunlop Scout (Big W) both which superficially appear to be the same frame, retailing for around the $80 mark when on special - like this weekend.  On the bike I've finally used, it is 370mm.  I would regard this as the minimum size to have, particularly if you have to use the adaptor plate.

aaron bike 3
aaron bike 4

Other problems with the latest bikes is the tube sizing.  The Maximal has a lower round tube of around 52mm OD, this was too much for the exhaust to accommodate and would need some serious pipe bending to overcome.  Flange mating only occurs on the left side of the engine, right side has a 5mm gap.

The top tube is also oval, the smaller diameter is 30 mm however the larger diameter is again around 50mm which results in the tank attaching threads being too short.  You can see with all of these mods adding up it would have outweighed that value of the bicycle by about 3 fold.

As it was, the bike I ended up using still had a front bar diameter of 30mm which was just too large for the front cast in bracket to handle.  I managed to use provided adaptor plate and, by using a longer bolt, the lower drink bottle attachment hole already existing in the frame (no need to drill!).  From the way I see the kit, the majority of the motor mounting seems to be done through the seat post mount, so the front plate attachment in this manner is just acting as a stabiliser.  To prevent vibration transmission to the frame and the bolt, I sandwiched rubber between the adaptor plate and the engine which seems to be working fine.

As a final tip, when looking for a suitable bike second hand, I'd advise either the Op Shops / Salvos / etc... or council clean ups.  Avoid Cash Converters and the like, the charge more than new prices.  The type of frame these kits need are no longer common new, but are the type most people are chucking out.  If I'd only had my kit 2 weeks earlier, I'd seen 6 suitable bikes that were out for our council collection in the streets surrounding me, 2 of which appeared to have flat tyres as being their only problem.  I could have saved myself $25, but I'm just getting picky here.

To quote one of your previous customers:
Z-box kit delivered        -    $265
Op Shop bike              -    $25
Huffy bike computer     -    $25 (wow as much as the bike!)
Bolt                            -    $3 (had to buy a pack of 12)
The fun you get from motoring around on a bicycle - priceless.  

Aaron Massey
Victoria Park WA

From Steve of Perth - January 2007

Hi Warren,

I read the tips from Julian on the inlet and exhaust work to his 70cc motor. I then did the mods to the inlet tract of my 50cc motor and particularly noticed that the inlet gasket  is undersize for the manifold and head inlet holes and acts as a restricter. I did the porting work and had some exhaust gasket paper material lying about and made one up. I used some gasket goo to mark the exhaust pipe imprint and get the size and location of the hole right. Opening out the inlet restrictor gasket provided a noticeable bit of extra go.

I thought that the tiny 9mm ID exhaust outlet on the end of the muffler was also very restrictive as most of the 50cc scooters around have about 15mm tailpipes coming from the mufflers. A 14mm ID pipe is more than twice the opening of a 9mm pipe. (64 sq mm vs 154 sq mm).

I found a stainless steel core plug in the shed that was a tight fit in the end of the muffler to replace the exhaust pipe dome on the end of the muffler. I filed a chamfer to help it fit snugly into the muffler tight against the end.

I then drilled an outlet hole in the bottom of the new "dome" as per Julian's tip but it was too loud and doesn't work properly as the muffler has two baffles inside and doesn't flow properly without the exhaust outlet tube returning the gases from the top chamber (it passes through both baffles without interfering with the upward flow of gases between the three chambers). The use of the return tube allows the required muffling to occur before gases exit the muffler. I used a bit of 14 mm ID steel (curtain) rod as the exhaust tube after removing the white paint with my oxy torch. I drilled the core plug centre for the screw hole as per the original dome. I then drilled another 12mm hole in the core plug hard against the side wall of the core plug and filed it out to take the 15mm OD exhaust tube fit as I didn't have a drill bit the right size. I then filed out the holes through the baffles in the muffler to take the 15 mm tube fit and used silver solder to braze it in place in the core plug as per the original design. You could run the drill through the existing holes if you had one and save lots of hand work. The 15mm tube fits easily between the core plug wall and dome retaining screw.

Once the dome was refitted to the muffler I rode the bike. It was not much louder than the standard pipe but there was a marked increase in power immediately. Once it warmed up there was a noticeable drop off in response to the last 1/4 of throttle travel. It was obviously running rich once the engine was hot and more vaporized fuel became available. I then took the slide out of the carby as per the Chinese instructions by unscrewing the top of the carby where the cable goes in and dropped the needle jet in the slide body to the lowest (top) notch. (Take care to avoid losing the spring and circlip and note how they go together). Once I had done this and reassembled the carby there was a further increase in power, sweeter running and less ringing and sputtering on back throttle. The 50ccc engine now does somewhere around 55kph on the flat, goes up fairly steep hills easily at a similar pace with minor assistance on the pedals to keep it in the power band and has to be freewheeled to prevent over revving going downhill. Some taller gearing could be in order. Definitely a worthwhile improvement. This mod should work on any 50cc bike and you still have the original part if you want to reverse the mod.


Trek Motorised Mountain Bike AND chain care from Julian - November 2006
Hi Warren,
Much has been said about everything but I have not read much on how to lubricate and maintain the CHAIN so after trying many products I found this is the very best. Bike lube such as White Lightning did not last long (wax lube) must put on almost every day.Crc TAC-2 is not bad but needs cleaning every week as it picks up a lot of dust. Tri-Flow with teflon base not so good,the teflon does not work till the oil has completely gone. Tri-Flow is a 20 weight oil same as WD-40 but in the Flax test for wear and load Tri- Flow failed. WD-40 under load and wear is 5 times higher than Tri-Flow, so they are both penetrating and water -displacing oils. What I have done is;  I clean both chains with WD-40 and a cotton rag (spray& rub) comes sparkling clean but don't forget to put a few sheets of news paper between chain and rim . I then wipe the chain down with another clean rag so it does not drip. I made a mix 50/50 of WD-40 AND GRAPHITE POWDER in an old singer oil  plastic bottle and apply it to both chains. The graphite will go into every moving bit of the chain and will still be a slippery lubricant even when the oil goes bye-bye. The WD will be your penetrating cleaner,and lubricant all in one and if you take my advice do not clean any chain in kerosene or petrol , by doing so you remove the very fine bust mixed with oil in between the links and when all that fine dust which is graphite is removed your chain is actually longer and out of pitch,therefore wearing all other components such as front &rear sprockets.


From Julian October 2006

Hi Warren, I recently bought a new mountain bike with the intention of mounting the motorised kit I purchased from yourself. However, during the process I realised nothing would be a simple fit and bolt on job, so with a bit of engineering skill I am glad to say it IS a total success. As a result, your web site could now say this motor kit CAN BE FITTED TO ANY TYPE OF PUSH BIKE; and of cause please find attached photos of my bike you can upload to your site to show as evidence. I thought you also might like to hear some brief details of the complicated process I went through to achieve this task: I started with solid 38mm round aluminium and machined it flat all over (see photos). I then did the drilling & tapping and counter boring before internal machining. I then measured the seat post tube size and found it was bigger than the distance between the studs on motor so it was not possible to mount it up in what would be a conventional way (see photos). The front tube was actually OVAL 55mm by 44mm and 1mm taper per inch where the motor had to be mounted. So, given it wasn't ROUND, I had to be very accurate in machining the bracket oval so it would fit frame (in addition, all sizes machined had to be larger in order to accommodate a rubber mount). How do you take something that is round, machine it to make it oval and then taper it...? I can tell you, it is quite a process to say the least! After this was completed I tested for the fit. I found the angle of the tubing was different to other bikes, so I now had to machine a wedge piece wider than the stud holes to offset to the correct angle. The fuel tank studs were then too short so I had to make joiners in stainless steel to ensure a secure mounting. As the brake and gear cables run along the top of the cross-bar I had to machine 1 nylon ring 1 inch wide, cut it in half, and then make 3 grooves on each so the cables could slide and not touch the petrol tank. This was then rubber mounted top & bottom. I reshaped the exhaust pipe to clear the frame and put heat wrap on the bend for safety and heat reasons. It was now time to fit the sprocket and encountered another dilemma. I counted the SPOKES and got a silly number of 32 SPOKES! I counted them over and over again and couldn't believe it (I always had believed 36 spokes on a wheel was standard). Given this unexpected hurdle and given replacing the whole back wheel was too expensive, I marked the pitch circle diameter to the existing holes and had to divide by EIGHT, not the existing nine holes which came pre-drilled as part of the kit (in any other situation this would have been fine on a 36 spoke wheel). I drilled some new holes including the rubber mounts and backing plates. The hub on the left side was too small and tapered so I had to machine the exact taper inside and then machine the outside diameter to match the centre hole in the sprocket. It was then placed in the centre hole of the gear sprocket to centralise on the hub. The eight bolts were tightened and with a dial indicator to get it to within 5 thousands of an inch (about the thickness of a sheet of newspaper). As a result of a little bit of innovative engineering and creative thinking the bike goes great, with no problems at all!! I will leave you to look through the photos and I think you may be very impressed.
Kind Regards, Julian


I hope you liked my last email & photos, my latest modification is the chain tensioner and it goes like this.

I went to the local bike shop and collected derailer idler wheels which in fact are all the same chain pitch as the heavy chain supplied in the kit. I machined the centre of the nylon idler wheel and then made a bronze bush with the centre hole to be a running fit on the original pin supplied where the nylon wheel would be placed. So now there is a nylon toothed wheel running on a bronze bush to stop wear and tear , the chain runs very smooth and the tensioner bracket does not move any more. The round nylon wheel supplied is a lot to desired,  the links in the chain give that nylon wheel a hammering and causes the support bracket to move forward and that is when the tension loss happens .  The new tensioner is not as wide as the nylon wheel supplied and it is to an advantage,It finds it's own centre point when the chain rotates,clearance on the bracket and end of pin. The bronze bush is 10mm wide.

From Julian Sept 2006
Hi Warren,   
The 70cc motor can definitely be improved so I will tell you what I did. I removed the carby and set the float 2mm higher than the main jet when holding the carby upside down, that eliminates flooding of the bowl . I removed the chrome inlet manifold,filled it out inside and removed all burs,the flange end was also filled so the centre hole is the same as the tube hole(bit of work to do that) The gasket on the inlet must be the same shape as the inlet of the head(Oval,not Round) need a sharp stanley knife to cut gasket and piston at the top so you can vacuum out any paper that might fall in. With exhaust assembly removed I filled the flange end till the centre hole is the same as the pipe size inside.   I removed the domed end of the exhaust  and remachined a new one with a 3/4 hole with no extension tube inside . Warren, it is slightly louder but not too loud ,starts much quicker without choke, idols perfectly, at 35klm/h  very little accelerator is needed and I would say there has been an enormous amount of extra power,I'm 107kg and no hill is a problem ,with a twist of the wrist it accelerates up hills that I would normally push my 14 speed push bike.

From Alasdair in September 2006

Warren a quick note to let you know your package arrived late on Friday through Fastway....  I called the local agent on Friday morning and he said the he had off loaded to another courier to be delivered Friday mid morning, was not delivered when I got home so I rang the local agent again and he gave me the mobile of the person the package was with, I spoke with him and indicated he was in my local area but it still took over two hours to make it to my door and it was delivered in a private vehicle at 5:30 P.M. Anyway opened the box and and found a typical bit of Chinese engineering nice design but the attention to the engineering detail is a bit lacking..... Spent a bit of time with the die grinder making sure everything works correctly and fits are good and smooth and proceed to do the installation........ The outcome rolled down the drive about 20 feet and the unit sprang to life plenty of smoke as I had lubed the piston and liner and pushed it around the back yard with the plug out and shorted for about 5 mins to ensure piston and ring well lubed and not binding in the liner, the unit pulled well and performed better than I expected....... Spent about an hour just pottering around the back streets letting it cool and then riding again..... I am impressed a real fun machine had my monies worth out of it already.... The only real concern that I have is very bad gear wine even though the helical gears were greased as per your instruction..... With more running the gears may bed in and run quieter..... By the way the instruction manual that came with the unit is pretty poor in the exploded view section but I was in stitches laughing with the technical translation in the rest of the manual.... Just one question you make mention of having the mixture screw out 4.5 turns but all I can see is an idle speed screw that moves the static position of the throttle slide.... any way having fun and thanks for the good communications and fast dispatch....... The Sky Star 70 cc units that are around are they yours??? and will you be getting and more of the 48 cc units and will you be selling them for the same price as the one I purchased ????
ps can't wait to get home from work tomorrow and back on the bike the Harley might stay parked for a while......

From Kevin in August 2006
  Just an update on the ongoing use of the zbox motor after 1 month of solid use. It gets used everyday for about 50kms. I'll have to leave the chain adjustment assembly on the bike permanently as the chain won't "clear" the frame without it. In which case I was wondering HOW LONG the nylon roller will last ? Do you have a steel roller or suggest an alternative - maybe a deraillier toothed roller or what ?? The twist throttle lasted about "5 minutes" so I replaced it with a spring loaded lawn mower hand throttle. Also I had to replace the "kill" switch as the supplied switch was a bit "tinny" and lasted about as long as the throttle. I fixed the "chain rattle problem" at low speed with graphite grease You might "adjust" your installation instructions to explain that a proper 16:1 fuel mix for the "new" Zbox 48cc motor = 65ml of (Penrite) 2 -Stroke oil to 1 litre of 91 Octane unleaded petrol. I'm still using the 16:1 "mix" after 1,000+ km........ On another subject - I notice you'll soon be selling 36volt electric bikes. I hope the battery charger - with the unit, is a "transformer" type of charger and NOT an "electronic" type as the circuit board type of electronic chargers last about "5 minutes" before they "cook up". I've had a number of various brand/distributor 36volt electric bikes - all supplied with 'electronic chargers' and sooner or later they all "fail"......... Which reminds me - can you supply me with a 36volt transformer charger after your 36v mountain bikes 'hit the market' or whenever ? Thanks ! Sorry, no pics yet of my installed 48cc Zbox motor as I'm still doing modifications to the bike, but thanks again for a beaut (cheap) motor ! Kevin C.

From Andrew Feb. 2006

Well its all finished and goes great. Not as much power as I thought (Struggles on hills and 45º Hills are impossible). Otherwise I was impressed with it. On the flat it doesn't take much to get up to speed. Average speeds I've been riding at is about 25km/h but mainly for safety on the bike paths. Fitting the motor to the bike was fairly easy. Slight problem with rear mount at the moment interfering with the gear change there. May be able to fix that by removing the stud and nut and fitting a bolt as it is mainly the thread that sticks out that gets in the way (Can take a photo and show you if you like) Front mount I used that plate but instead of drilling a hole and bolting it there it was positioned nicely where the bolt for the drink bottle holder bolted in and I sat it over that bolt and got longer bolts to fasten it with the clamp (Again can take photos for illustrations). Only other modification was to the chain guard where I had to cut it little to fit. Oh and my chain tool broke on me when I was working on it (Night) so had a frustrating time adjusting the chain. Only other thing that has happened is the idler wheel came of somewhere while riding but since the chain is quite tight as it is I don't think it is a problem. Anyway here is a photo for you to look at: Feel free to use it on your site and if I can assist don't hesitate to ask. Thanks for a great motor! I hope you do well. I have also thought about your ideas of selling completed bikes. Might think of that in the future.
Thanks for your support.

large frame fitting

I was just so relieved to find someone selling the motor locally and for a reasonable price.
And you have been a great help and it was good to get one on one interaction.
Keep up the good work. BTW are you going to expand from here? Other motors/accessories?
I did think of cutting up an inner tube but didn't find an old one till after I'd finished.
I did use some electrical tape but when I next do work on the bike I will replace that.
I was mainly thinking of protecting the paint at the time.
Also noticed the exhaust seems to curve too much and can't get it to bolt up tight.
Hence there is some leakage out from the manifold.
May need to see if I can get it adjusted/bent.
The website I have up with the pics is only temporary at the moment to show a few friends and
family. When I get around to redoing my website later this year I will do  proper page.
I'll add a link next time I edit the page but I don't have many more people to show it to.
I have got one friend that may be interested in buying one sometime though.
And I am still thinking of building another one to sell once I get another bike I can use.
Also I took a long ride on Sunday (To visit a friend). Nearly 100km for that day. Used about 1/2 a tank.
I actually took extra fuel just incase. Took about 4 hours for the total ride.
Here are the stats:
Trip to Chapman & Back (Isabella Plains):
Total Trip Distance: 94.6900km
Average Speed: 23.6100km/h
Total Time Taken: 4:00:36hr
Max Speed: 50.4000km/h
Bike went well. Only 1 problem... I got sunburnt arms and face LoL
A little tiring. I stuck to the bike paths mainly.
Not much effort needed at all. Let the motor do most of the work.
All up it was great.


zbox caution

Home    About us    Electric    Spares    Instructions    Business Opportunities
Large Engine    Bikes    Contact    Legislation    Tips    Buying Guide    Orders

page last updated on 15th June, 2018
ZBOX Australia is a division of Cybervision Pty. Ltd.
© 2012 ZBOX Australia