Fuel Mixture – Oil/Gas Ratio – 20:1 Motorcycle Synthetic 2 Stroke Oil (7 ounces per gallon)
This engine is a 2 cycle design, therefore, a gasoline/oil mixture is necessary. During the break in period (1st 2 gallons of fuel) and after, the ratio is kept at 20 parts gasoline to 1 part oil. Use a good quality MOTORCYCLE SYNTHETIC 2 STROKE OIL. This ratio is achieved by mixing 7 ounces of Synthetic 2 stroke oil with 1 gallon of gasoline. We suggest purchasing a fuel container and pre mixing in the gas can.
The break in period for your new engine will last 4 tanks which is approximately two gallons. During this time, you should keep your rpm’s low and the length of ride time to a minimum. If your new bicycle engine is being fired for the first time, start the engine and allow it to idle for a couple of minutes and then cool back down before taking your first powered trip. Optimally your riding habits during break in would look like short trips no longer than 10 minutes with speeds no greater than 15mph for a 44 tooth drive sprocket and 20 mph for a 36 tooth drive sprocket. Allow the engine to become cool to the touch between each ride (approximately 20 minutes). While the rings and bearings are initially seating, fuel mileage can be as low as 50 to 80 miles per gallon.
After the break in period remember that these air cooled 2 strokes receive lubrication from the oil which is mixed into the gas. Extremely long trips in hot weather or extended idling times in traffic reduce the lubricating ability of the 2 stroke oil to protect the cylinder wall from friction due to thermal break down which could result in piston seizure.
* Every day riding, pay attention to three main areas around the engine. While the engine is cool, with a 10mm wrench, carefully snug up the 2 nuts securing the carburetor intake manifold, 2 nuts securing the exhaust, and tighten the 4 nuts on top of the cylinder head. Use caution to not over tighten. Finger tightening to a max of 5 feet/pounds of torque should be sufficient. Around the rest of the motorized bicycle, tighten and secure every nut, bolt or screw as often as possible.
Part Description & What to Watch For:
* Front Wheel & Fender - make sure the wheel is secure, the wheel is true, the tire pressure is correct, the tire bead is seated properly and uniformly across the rim, and the fender strut nuts and bolts are attached.
* Rear Wheel – make sure the wheel is secure, the wheel is true, the tire pressure is correct, the proper tire bead seat, the chain does not rub on tire, the coaster brake arm is attached (when applicable), and the wheel bearings are within adjustment and there is no play or tightness in the bearings. Adjust the rear wheel in the dropouts if engine chain rubbing occurs. To either center tire into position or adjust chain tension, loosen one side axle nut and then pull the portion of the wheel closest to the bottom bracket towards you and then retighten that side axle nut. Then, do the same to the other side until the rear wheel has the same distance between the engine drive chain and the right side chain stay…i.e. loosen the right axle nut, pull the wheel to the right, retighten the right axle nut; loosen the left axle nut, pull the wheel to the left, retighten the left axle nut. “Walk” the wheel back until both chains are tight and the wheel is centered between the two chains and not rubbing.
* Special note – Never move the coaster brake arm once either axle nut has been tightened. Bearing adjustment can go out of whack if you don’t pay special attention to how and when you position the coaster brake arm. To remove a coaster brake wheel, detach the coaster brake arm bolt first then either side axle nut. To reinstall a coaster brake wheel, slide the wheel into position with both chains on their sprockets, tighten the coaster brake arm hanger, loosely tighten the right side axle nut, then the left side axle nut. Next, follow the procedure above for “walking” the wheel into position.
* Chain Tensioner - The chain tensioner acts in many ways the same as a derailleur guiding the chain onto the sprocket. With the clutch in, check that the tensioner guides and centers the chain onto the sprocket teeth in the middle of the chain. If you have to reposition the chain tensioner to adjust for chain slack or if the tensioner gets knocked out of position somehow, make sure that the chain tensioner is fastened with self tapping screws to support the side load that occurs during engine start up and overrun/deceleration. Always keep a half inch to an inch of slack in the engine drive chain.
* Clutch Free Play - Too much clutch free play or too little clutch free play will not allow the engine to engage. Adjust the free play as needed, either on the clutch lever at the barrel end adjuster for fine adjustments or on the engine at the clutch arm’s cable stop for gross adjustment.
* Before each ride check all nuts, bolts, mounting fasteners and safety equipment.
* Open the fuel valve. When the small lever is parallel to the fuel line, the gas is on. When the lever is sideways, the valve is off. Remember to always turn the valve off when the bike is not in use.
* The small lever on the right side of the carburetor is the choke. Lift the choke lever up to start the bike when the engine is cool to the touch. Keep the choke down when the engine is warm. The choke should only stay up for a few seconds of riding and should quickly be pushed back down for normal riding.
* Pull in the clutch (left handlebar lever). Pedal up to 5 or 6 miles per hour. Quickly release the clutch lever while continuing to pedal, pull back the throttle and the engine should start. Push the choke back down and allow the engine to idle and warm for several seconds before riding away.
* Once the engine is started, always pull in the clutch lever before coming to a stop to allow the motorized bicycle to idle. With the engine running, always pedal away from a stop before releasing the clutch to assist the motor.
* To stop the engine, push kill switch button and turn off the fuel valve.
Poor Starting Scenario 1
Hold in the clutch. Let out the clutch. Keep pedaling while the engine turns over and you can hear the piston moving up and down in the cylinder. The bike does not produce any power.
1. Make sure all nuts and bolts are snug per maintenance instructions.
2. Check the fuel.
3. Check the fuel valve. Down and in line is on. Sideways is off. (Always turn the fuel valve off when not in use to avoid accidental spills.)
4. Check the position of the choke. Down for normal running and warm starting. Up for just a second during cold starts.
5. Visually inspect that fuel is in the fuel line. All that is needed is a trace amount. Pressing the ‘tickle’ button several times with the fuel valve open can help with this.
6. Check to make sure that all of the electrical connections leading from the magneto are connected. Blue leads to blue, black leads to black as the wires enter the CDI box from the magneto. Make sure that a proper connection is being made in the spark plug boot. Inspect and/or replace the spark plug. Correct spark plug gap is 0.038″.
7. Follow the white wire as it leads from the magneto up to the kill switch. On certain models, the kill switch may be at fault grounding out against the handlebar. Disconnect the kill switch at the handlebar and attempt to restart the bike.
Poor Starting Scenario 2
Hold in the clutch. Let out the clutch. Keep pedaling and the bike drags to a silent halt. The engine does not turn over.
1. Clutch free play. A small amount of free play is needed in the clutch lever. Too much and the bike won’t start. Too little and the bike won’t start. Small adjustments can be made in the barrel end adjuster at the clutch lever, while major adjustments are done at the clutch arm cable stop at the engine.
2. Check that the engine chain is not bound around the output sprocket inside of the engine. An improperly adjusted chain tensioner can cause the drive chain to bind within the engine.
3. Remove the right side clutch plate and inspect the condition of the 2 gears, the small main pinion gear and the larger clutch gear, for wear.
4. Remove the 4 screws on top of the cylinder head. Carefully remove the cylinder head and head gasket. With one hand securely hold the cylinder from moving. With the other hand, gently push down on the top of the piston. Inspect the cylinder wall for scarring or abrasion.
Consistently running at full RPM is about the worst thing that can be done to an engine long term. Always running at full throttle does not leave enough time for the oil mixed in the gas to circulate around the engine and lubricate the cylinder wall and lower engine bearings.
If you are going to run at high RPMs, do a plug check. Pull the spark plug once in a while and see what color it is. If your plug is tan, white, dry and clean, then you need to either slow down, not ride for so long, and/or increase the oil/gas ratio. If your plug is black and moist, then you’re doing well. Even better is if a little black drop occasionally falls from the exhaust tip.
If your spark plug is black, dry, and sooty, then it may be time to clean the combustion chamber. “Decarbonization” was a common maintenance procedure in the days when British motorcycles roamed the streets and leather clad rockers owned the roads. You need to keep a clean environment in the combustion chamber. With high mile heavy use (5,000 miles+), we do see a build up of carbon beneath the cylinder head and on the combustion chamber. If the carbon buildup is thick, this barnacle like substance can cause a piston seizure if any small piece breaks off and lodges between the piston and cylinder wall.
To “Decarbonize” an engine, remove the 4 nuts on top of the cylinder head, remove the cylinder head and metal head gasket. Bring the piston to the top of its stroke. Using sand paper or a soft wire wheel, remove the carbon from the top of the piston crown and the bottom of the cylinder head. Be careful not to score any of the inner surfaces.
FOREIGN PARTICLES ARE THE ENEMY! Clean your air filter often.
Commonly Used Tools
o 8mm – 17mm metric wrenches
o 4mm Allen wrench
o 5mm Allen wrench
o 6mm Allen wrench
o 8mm Allen wrench
o Flat-Head screwdriver
o Phillips screwdriver