How many times have you hopped on your motorized bike for a ride, pedal, let the clutch out and… nothing? We’ve all been there, so it’s good to know what to look for to fix the problem and get you on the road. Here we’ll focus on two major issues we hear when riders can’t get their motor to start:
Scenario 1: My clutch is grabbing but the motor won’t start
Imagine you’re holding in the clutch, pedal your motor, and release the clutch. You keep pedaling and can hear the piston moving up and down in the cylinder, trying to start the motor but you’re not getting any power. What do you do?
1) Make sure all bolts are tightened down around your engine
Make sure all nuts and bolts are snug per maintenance instructions, including the cylinder head, manifold, and exhaust studs. If your studs aren’t tightened you can be allowing air leaks around your engine, which leads to a lack of compression. (Note: cylinder torque should be 10-12 ft/lbs)
2) Check the fuel flow in to your motor
Pistons move down the cylinder when the spark from your spark plug ignites the gas from your motor and creates an explosion that sends the piston back down the cylinder. If you’re not getting fuel in to your engine that explosion won’t happen. First, start by looking at the fuel line and make sure it’s filling with gas.
If the motor’s not getting fuel, make sure the gas tank is mounted above your motor (this motor’s gravity fed, meaning fuel travels downward in to the engine instead of being pulled in to the motor).
If it’s mounted correctly remove the gas cap of your fuel tank. If the fuel travels into the cylinder with the cap off it is an indication that your fuel tank is not breathing. When that’s the case, replace the gas cap with one that allows a slightly looser seal. If you do not want to replace the part, you can also drill a pinhole in the gas cap to allow the tank to breathe.
3) Check your Fuel Valve and Choke Lever
Fuel Valve: The Down position means the fuel is on; sideways means it is off. Always turn the fuel valve off when not in use to avoid flooding your motor. Be sure to also check the filter on the end of the fuel valve to assure it is free of debris and blockage.
Choke Lever: The choke is located on your carburetor and it’s used to warm up the engine. You’ll want to make sure the lever is lifted up when you start the motor: that means the choke is on. When your motor’s warmed up (you’ll hear the idle raise significantly), push the choke down to open the choke. Depending on the temperature in your area and the time of year, the choking time will vary. When it is warm outside you won’t need to choke the engine as long; in cold weather you’ll need to choke the motor longer.
Scenario 2: My clutch isn’t engaging the way it’s supposed to
Now imagine you hold in the clutch, pedal your motor, release the clutch, and instead of the engine starting the bike drags to a halt. What do you check?
1) Check the clutch cable tension
A small amount of free play is needed for your clutch cable to work properly within the clutch lever. Too much or too little free play and the bike won’t start. If you need to adjust the play slightly, you can do so on the barrel end adjuster at the clutch lever. Major cable adjustments can be done at the clutch arm with the clutch wire clip (or clutch cable stop).
2) Check the chain tension
Check the chain tension. An improperly adjusted chain tensioner can cause the drive chain to bind within the engine, leading to the chain snapping. Check that the engine chain is not bound around the drive sprocket inside of the engine. The play on the top of the chain should be between 1/4-1/2″ of play depending on the motor you have.
3) Check out the small and large bevel wheels for damages
4) If it’s still dragging, adjust the clutch