Introduction: 80cc BICYCLE Motorized ENGINE KIT

This kit will allow you to turn your bicycle into a gasoline powered motorbike! 1 Gallon of fuel runs 150 miles!! The engine is designed to be pedal/chain started so you can start or stop the engine while riding! Speeds up to 40mph. To install this kit you will need some basic skills using tools and a few hours. Follow the user manuals stated gas/oil mix and adjustments. This kit will fit many bikes sold in your local bike shops!




There are two rear sprocket rubber packers. Cut one of them and only one. Cut only between the drilled holes.
Place the cut one inside of the spokes.
Place the other packer on the outside of the spokes.
Thread the nine bolts through the sprocket and use the half moon backing plates on the inside. Tighten all nine bolts moving across in a star fashion and a little at a time to allow for an even pull down. Once the sprocket is tight spin the wheel and check that the sprocket runs true.
Deviation can be no more than 1.5mm both ways. Any side-to-side excess deviation can be corrected by spinning the wheel and then tightening the sprocket where needed in order to get correct alignment. Make sure bolts are tight. Notice that concavity or indentation of teeth of the rear sprocket is inward towards spokes. This helps keep the chain closer to the inside of the wheel and spokes and allows for better clearance of the rear stays of the bicycle frame.


Mount the engine into the frame. This is the front motor mount. Some bikes have a large diameter lower bar and some need clearance for the air box intake so you need to use the parts provided in the kit. Use spacer provided with the kit (spacer bar is not included in the some kit). This spacer normally would require the drilling of a hole in the frame to bolt the centre of the spacer through (shown below). I prefer the method shown, which is to pull the studs and replace them with longer ones (threaded rod) that you can get at the local hardware store. Then, you can use the steel motor mount clamp that came with the kit and not have to drill a hole in your frame. Then cut the excess off. My bike had an ovoid shaped lower bar about 50mm across. I used this method.
STEP 2 (if needed) 
Always mount air intake with inlets down!! Always!! If you need to, you can put the air box on a grinder and cut down on the inlet tubes a little to make sure they clear the frame. If you use the spacer on the front motor mount, usually this is enough to clear. Also, you may need to file down any water bottle screw mounts if they protrude and are in the way of a motor mount.


Lightly grease right side handle bar end. Slide throttle on all the way and then back it off a hair and then tighten it down evenly. Do not over torque the screws. If you get real ambitious, unload cable from carb slide and from throttle end and clean up the fiber plastic and lube the cable sheath and re assemble.
Mount the clutch lever.
Screw in the fuel valve filter combo into the tank and then mount the tank. Tip...Wrap top frame tube with bar wrap where tank clamps are. Also...If you have cable runs on the top bar that are open cables, you may need to run them through cable sheath the length of the tank in order for them to work once tank is clamped over them. Apply plumbers tape to thread if leaking.
Mount your Coil. Tip...Use 2 high quality cable zip ties. Go up and over and around the coil and zip tie it to the frame. Loop one zip tie up and over and also through the holes that would normally have the screws going through them. This is a better method than using the screws that come with the kit. You will have a more solid mount and not break the coil. It is not hard the break the coil ears off using the screws...Wire Connections...Blue to Blue and Black To Black. Also..Tie Kill Switch to the Blue wire / earth. The white wire is generator and has a max output of .5A 7.5V. Anything that draws more current connected to the white wire will kill the motor.

Step 4: FITTING CONTROLS (continued)

Remove the 3 screws from Counter shaft side cover and also remove spark plug. Remove clip from master link of chain and then thread chain up and over counter shaft sprocket by rotating the sprocket using tool. Having the spark plug removed allows engine to be turned easily to thread chain. Tip...Since you have this cover off, Hold clutch arm and rotate cover and pull clutch arm out of cover and then grease it and rotate it back in.
Put some molly grease on the shaft and in the hole.
Cut chain to length and using master link put chain back together. Do not cut chain too short !! Install Idler pulley. Make sure you grease the plastic wheel metal shaft. Do not over tighten chain. Install chain guard. Use some tin snips to cut cover at the rear if needed..Use a good zip tie at the rear and the extra long bolt for the counter shaft cover will hold the front.
Install exhaust pipe. If you need to bend the pipe some so it will not hit the frame or bolts, clamp the pipe into wood blocks and bend. Do not bend exhaust mounted to engine. If you do..You will not bend the exhaust, you will break the motor!! Exhaust pipe is very strong. Much stronger than the 2 mounting studs on the motor.
Mount the carburetor. Check the other screws including the brass fuel inlet screw for tightness..Typically they need some slight turning. Once the carb is on and
tight...You are ready to connect the tank line to carb. Tip...Get and inline fuel filter. Even though the fuel petcock has a screen filter, it is porous and allows sediment through.. A high quality inline fuel filter with paper element is a super way to go and to keep fine particulate out of the carb and the engine running fantastic and like new. Well....Install is done..Mix your oil with the petrol before adding to tank...Fuel up the bike..And...go baby go !!!!! Enjoy!!! Ahh..do not get too excited...This is a new motor and you need to take it easy for the first 500 kilometers or so ...Oh well..the price of owning a new engine...You have to run it in....But..That is fun too...Enjoy!!!!


Remove carb cap and lay out all the parts
Place needle into center of carb slide and then put flat washer with groove on top of needle making sure you have the groove lined up with the groove in the carb slide
Install cable to plastic grip first, then thread this end through the carb cap and through the spring
Compress spring and load cable into the end of the slide. Once you have it started, put the entire length of the cable into the slide, once you have done that, release the spring to the inside of the carb slide allowing the spring to push onto the flat washer and thus holding the needle down.


1. Clutch:
a) Remove right side cover from engine.
b) Place a small dab of grease at gear mesh area.
c) Replace cover.
2. Carburetor
Depending on dusty riding conditions, clean air filter every 5 to 20 hours of operation by removing the filter cover to access the screen and element. Wash element with a degreasing agent. Be sure element is completely dry before re-assembly.
3. Spark Plug
Remove spark plug and inspect for excess carbon build up. Clean, re-gap to .6mm - .7mm if necessary. Check plug after every 20 hours of operation. A suitable
replacement plug is NGK BP-6L if you can find it. Otherwise, go for the NGK B-6L. The NGK R7-HS is also recommended for better performance and smoother idling.
4. Exhaust system
After 20 hours of operation check exhaust pipe for excessive oil and carbon build-up. Be sure to use supplied support strap to secure exhaust muffler to a solid anchor point on bike frame or engine.
a) Remove exhaust pipe cap by loosening the retaining screw. b) Pull cap and baffle out of pipe.
c) Clean with degreaser, rinse and dry.
d) Re-assemble
NOTE: Excessive periods of low speed operation, idling or leaving fuel petcock in the “on” position during shut down periods may cause the pipe to become clogged with unburned fuel.
5. Chain
Every time bike is ridden check the tension of the drive chain by:
a) Rolling to bicycle forward to remove slack from the bottom of the chain.
b) Find the center and push downward on the top of chain while measuring the deflection.
c) Tighten chain if deflection is more than 15mm.
d) Low speed "chain rattle" can be eliminated with the application of graphite grease to chain.
6. Head Bolts
Tighten all fasteners after each five hours of operation. It's most important to check cylinder head bolts: tighten in a X pattern to 12 ft/lb. using a torque wrench. A two piece cylinder and head design engine requires head bolts be kept tight. Important: Check head bolts before each and every ride, vibration can cause them to loosen and blow a head gasket. Caution: Do not over torque or head bolts may break off.
7. Right side gears
Remove cover plate and keep small amount of heavy grease on gear train. Do not over grease as leaks will occur and also may adversely affect clutch operation. Regular greasing if required will help reduce gear wear and keep gear train quiet.

Step 7: General Information

Obey all traffic regulations. Always wear an approved helmet whilst riding. Remember that you are riding a motorized bicycle and other traffic may not be able to see you. Never operate your motorized bicycle on a pedestrian thoroughfare or pathway whilst the engine is operating. Never operate your motorized bicycle in an unsafe manner. Check local and state laws before riding on streets.
WARNING! ALWAYS wear a helmet whilst riding.
Motorized bicycle starting and operating instructions
The engine is a 2 stroke design, therefore a petrol/oil mixture is necessary. During the first 500km break-in period, the ratio for engine is 16 parts petrol to 1 part high-grade 2 stroke motorcycle oil (65ml Penrite 2 stroke motor oil to 1 litre of 91 octane unleaded petrol). After the break-in period, the ratio is increased to 20 parts petrol to 1 part oil(50ml Penrite 2 stroke motor oil to 1 litre of 91 octane unleaded petrol).
Be sure to mix fuel and oil before adding to tank - don't add separately.
Do not exceed 20km/h during break-in period. Speed may be increased to 35km/h after the first 500km.
Use only high grade 2 stroke motorcycle oil to ensure proper engine lubrication.
WARNING Remember safety first: Wipe up any spilt fuel. NEVER refuel a hot engine or smoke whilst refueling. This could result in fire and personal injury. Always move your motorised bike at least 3 metres from any refueling area before attempting to start it. Never leave the tank fuel cap off after refueling as rain water could contaminate the fuel and cause engine failure.
1. Open the fuel valve. Small lever pointed down with fuel line is in the open position.
2. Depress the small round cap plunger (tickle button), to prime carburetor. One or two times is enough.
3. Lift choke lever to the upward position. This is the small lever on the right side of the carburetor. All the way up the choke is on. All the way down the choke is off. Move progressively downward to off position during engine warm up period.
4. Pull the handlebar clutch lever inward, to disengage the engine from the rear wheel.
5. Pedal (down hill if possible for first start).
6. Let out the clutch lever all the way out and continuing to pedal. The
result is a direct engine hook up with the rear wheel via chain and sprocket and the engine will now start spinning, Pedal until motor starts. Accelerate slowly at first.
7. Twist throttle to increase speed, reverse twist throttle to decrease speed. To stop, disengage clutch and apply brakes. To accelerate, pedal and release clutch whilst opening throttle.
8. Adjust choke to the smoothest engine running position.
9. After warm up push choke lever all the way down. If engine
races too fast, or too slow, pull clutch lever and lock in the notched
catch, stop and adjust engine rpm.
10. If the rpm needs adjusting, turn the idle adjust screw (top of
carburetor) in or out slowly to obtain the proper idle speed of about 1400 rpm +/- 100 rpm To correctly break the engine in, do not exceed 25 kph or 30 min. continual running for the first 80 klms during engine brake in. Engine will develop more power after break in.
11. To stop the engine, push Kill switch and turn off gas valve at
tank. Turning off the gas will prevent fuel from being siphoned from tank. Warning: Never leave the tank gas valve in “open” position” when engine is not running or the bike is in storage.
12. After or before each ride check all mounting fasteners, including head bolts, axle and brakes.
13. Warning: Engine lock up or piston seizure due to improper petrol/oil mixture will occur. This the responsibility of the owner/operator to make sure the petrol and oil is mixed correctly.



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    17 Discussions

    My back spocket keeps coming off what am i doing wrong

    i recently bought a fully built brand new 80cc,motorized bike,followed the mixture and instructions to the letter,but after cycling down the hill outside,checking for a spark,all the fuel lines,putting the choke in every position possible,i cannot even get it to fire-not even a hint of a "chug" when i let the clutch lever out.im a retired car mechanic with LOADS of 4 stroke auto engine experience but have never had any 2 stroke experience in my life and this has left me totally stumped!can anyone please give me some advice,or any idea of where im going wrong,as the vender where i purchased the bike from is from overseas and is of no help whatsoever.i have checked over the motor to the best of my knowlage and cannot sea any problems or reasons why i am getting nothing?if i even got a"chug",then i would know i was on the right path,but after LOADS of attempts theres not even a tickle?can anyone help or offer any advice please??..would be much appreciated--john

    1 reply

    These instructions are
    good in some aspects and lacking in others. There are a lot of generalities and
    lacking details. There isn't much info on how to install the throttle cable to
    the throttle grip. It goes to Step 4 Controls continued… then show
    pictures of spark plugs, tensioner, chain guard and other unrelated
    details. Where is the info on how to install the throttle controls to the grip?

    have friends i am thinking so much so friends tell me any ideas


    2 years ago

    been reading up on uk regs, looks like its supposed to have an dvla inspection, and it falls under the classification of motorbike rather than assisted bicycle, than its get a log book numberplate tax and insurance, and im not sure if i need a cbt on top of my full drivers licence. Also its supposed to have a mirror on a specific side and a headlight with a dipped diffusion patturn. Driving without insurance attracts a chunky fine and other nastiness from the law. think i will stick to private land to mess with mine , unless im feeling flush,also tax is continous otherwise an annual sorn notification has to be made with details of its location, im putting a coaster on the back and a disk on the front,using an aluminium frame and slick skinny tyres..

    im having a problem with chain clearance its rubbing on my tire. My bike is a huffy cruiser coaster breaks so i cant use both spacers. i need to mount my motor outwards slightly to get the clearance i need. mounting it to the frame is not going to work using the rear brackets that come with the kit. it was sugested that i drill a single hole in the frame and mount it using one bolt. this brings it out too far. any ideas how i can mount it to get the clearance i need?

    Hey man! will the motor be able to a bike with the a seat tube thats 32mm and a downtube thats 36 mm? it would be awesome if you could anwser this as i want this enginge kit as fast as possible :D Btw great instructable!


    3 years ago

    I've been riding these in the UK for the last 6 years. built many bikes now for myself and friends. Brest advice is to just keep up on the maintenance. problems I've encountered in the past are :- chain idler deciding it wanted to be part of the wheel at 40mph - yes that hurt. make sure your mounts are right and true - of not the vibrations will just snap the studs. most importantly - remember the fuel/oil ratio a of you get it won't you will seize the engines. I seized 2 in 2 weeks after stupidly under oiling the fuel.

    uk is notorious for laws and regulations - i'm certain when brits leave to visit us they fall in love with more freedom ...

    just about the whole purpose for one of these is so u dont have to register, license and certainly not insure a stinking bicycle !! people with DWI's that cant drive a car use these to get around, .. also some homeless do .. and people not wanting the expenses of a car living nearby things .. 5-6 miles is a long haul on one of these , the 50cc ran good , with proper break in and gentle use .. u give it to a teenager who wants to test limits and itll be gone inside of 2 weeks .. 20mph is about right .. too much more and your winding the engine hard (25-30) ... 10-15 is also nice cause its quite and very stable/controllable .. again, i cant emphasize enough, coaster breaks are insufficient at these speeds .. if your in the country then thats a different story ..

    i did the 50cc kit few yrs ago .. 1st one did it part time took a month jan to end -- coaster bike breaks are not enough for stopping power - need disk or calipers, which do not come on a beach cruiser standard ... the chinese instructions had many many extra things to do, were poorly written/missing things .. it was a lot of work .. prob 8 hrs my first one from start to end ... and certain areas have legality issues .. the muffler system can be improved (made quiter) by putting a foot of electrical conduit onto the end of it and also gets the smoke going behind you more .. instead of the sound reflecting off the ashalt underneath ..

    I installed mine 2 months ago and LOVE it! I'm 2 1/2 miles up a dirt road and if it does get bogged down, which is rare, I just have to pedal a little bit to get me up the hill. You need to stay on top of it thought. Check all that maintenance stuff, double-nut your connections when you can and locktite when you can't. Always keep the tools with you to do a complete tear down and rebuild, and always wear a helmet.

    I had one of these motor kits once. It was so cheap, that the motor literally fell apart. All the taps for the holes in the crankcase stripped out, and there was even a casting flaw where there was a big hole in the crankcase. Ran like garbage, was unbalanced, extremely loud due to cheap aluminum case, and never idled right. Didnt even get 70 MPG. more like 30. Also never went faster than 27 MPH. Be old-fashoned. build your own motorbike. Stay away from this China garbage.

    1 reply

    Thanks for the advice, but mine works great and aslong as you know what you are doing you can work around the problems.

    Warning: in the UK, this conversion will require you to:

    > Have a full motorbike license, not a provisional
    > Get an independent MOT check on the vehicle (they will probably require you to upgrade the brakes to motorbike quality)
    > Have full insurance
    > Fit proper license plates
    > Wear a proper motorcycle helmet
    > Install a full lighting system, including indicators and license-plate illumination