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 into 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 into 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 into 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
Remove the clutch plate on the right side and inspect the condition of the
small and
large bevel gears for wear. Also, check to see if they are flush with the motor. 4)
If it's still dragging, adjust the clutch
97 comments
BikeBerry
“Hello Andrew,
Yes, it can if it is over-torqued you can lose power and compression on the engine. Be sure your engine is torqued down to about 10-12ft/lbs and also make sure that you are peddling for more than a minute to keep the engine going."
Sean oneill
Check for faulty kill switch it happened to me
Anonymous
I have a bt80 electric start and i love it
BikeBerry
“Hello Keith!
We are sorry to hear about that Bud!
We got you covered if you exhausted all troubleshooting steps and you still are having an issue. Then you would want to check the carburetor to ensure that the float bowl is not flooded or damaged. You always want to also make sure the correct fuel to oil ratio is being run through at 16:1 during the break-in and then 20:1 post-break-in. You do not want to flood the engine due to flooding causing the spark to die out. So check out those steps and hit us up if you still run into trouble."
Anonymous
Great Guide, tricky carburetor but great insight.
Anonymous
if you really work and follow these steps it helps, can’t tell you how long it has taken me to learn that.
Andrew mcgowan
Can having your head on your engine tight make the engine not start up but when it starts up I can only go on it up and down the street and then it cuts out
Michael Wolfe
Ethan take side cover off and see if the chain triangled inside gear case. More than likely that’s what happened.
BikeBerry
“Hello Andrew,
Yes, it can if it is over-torqued you can lose power and compression on the engine. Be sure your engine is torqued down to about 10-12ft/lbs and also make sure that you are peddling for more than a minute to keep the engine going."
Anonymous
“Hey,
I will try this with my troubles thank you "
BikeBerry
“Hey Rodney!
Great question, the fuel to oil ratio during your first 4 takes would be 16:1 so this is 8oz of oil to 1 gallon of gas. After the break-in period, you would switch it to 20:1 and this would include 6oz of oil to 1 gallon of gas. We would also suggest using synthetic 2 stroke oil for the best results."
Sean oneill
Check for faulty kill switch it happened to me
Anonymous
I have a bt80 electric start and i love it
BikeBerry
“Hey there Benjamin!
Usually, when you come across this issue it is because the clutch would need to be adjusted. Once you have that adjusted you will lift the pads closer to the plate. You can see how to adjust your clutch <a href=""https://youtu.be/zAp8h9WRXwI"" target=""_blank"" rel=""noopener noreferrer nofollow"">here ."
BikeBerry
“Great Question!
The correct fuel ratio is 16:1 for break in which is 1 gallon gas to 8 oz oil. The break in period is 4 tank fulls. After the break in period you will then use a 20:1 fuel ratio which is 1 gallon of gas to 6oz of oil."
BikeBerry
“Hey there,
That is a common issue at times, but we got you covered. If your chain keeps getting stuck look at or how to video <a href=""https://youtu.be/-5g3SqxzL8Q"" target=""_blank"" rel=""noopener noreferrer nofollow"">here "
Anonymous
This is what I needed thank you for the help bikeberry
BikeBerry
“Hey Christopher.
This is a common issue that comes intact with the engine kits. If the clutch is not disengaging then you would need to have that adjusted. The problem that is happening is the clutch pads are too far apart the clutch and it is causing it not to touch. Have that clutch adjusted and you will see the difference when you hit that clutch"
BikeBerry
“Hello Keith!
We are sorry to hear about that Bud!
We got you covered if you exhausted all troubleshooting steps and you still are having an issue. Then you would want to check the carburetor to ensure that the float bowl is not flooded or damaged. You always want to also make sure the correct fuel to oil ratio is being run through at 16:1 during the break-in and then 20:1 post-break-in. You do not want to flood the engine due to flooding causing the spark to die out. So check out those steps and hit us up if you still run into trouble."
BikeBerry
“Hey Odin!
Let us help you out with that. In most cases when you run into this issue where your clutch dies when it is pulled this means you would need to have the clutch adjusted. This is a real simple step and will happen on a brand new engine. Check out <a href=""https://youtu.be/zAp8h9WRXwI"" target=""_blank"" rel=""noopener noreferrer nofollow"">how to adjust your clutch and let us know if that did the trick for you."
BikeBerry
“Hey Cruz.
This is a common issue believe it or not so you are not alone. Here is what you need to do, you would need to smooth down the drive sprocket so it can take the chain a little better. We have a video that is based off this issue. View our If Your Drive Chain is getting stuck <a href=""https://youtu.be/-5g3SqxzL8Q"" target=""_blank"" rel=""noopener noreferrer nofollow"">here."
BikeBerry
“Hey Joe,
We do apologize we no longer carry the 212 Predator Engine."
Anonymous
Great Guide, tricky carburetor but great insight.
Rodney l Wright
I bought a stage III two cycle and was wondering the mixture ratio .
Anonymous
if you really work and follow these steps it helps, can’t tell you how long it has taken me to learn that.
AB
“I just bought a used motorized bike as is, everything seems to look good but I have one problem.
I can’t pedal and the only way to pedal is only when i remove the spark plug and both chain turn.
Why is that.
Thank you in advance for your help
AB”
Andrew mcgowan
Can having your head on your engine tight make the engine not start up but when it starts up I can only go on it up and down the street and then it cuts out
Anonymous
I just put together an 80cc 2stroke on a Kent for the first time and am still in awe of how great this runs, for the money and the time spent it is worth it
BikeBerry
“Hey Daniel,
The correct OHMS reading for your <a href=""https://www.BikeBerry/catalogsearch/result/?o=megneto&q=magneto"" target=""_blank"" rel=""noopener noreferrer nofollow"">Magneto would be between 320-350 on a 2k setting. In regards to the CDI we do only require to use a<a href=""https://www.BikeBerry/catalogsearch/result/?cat=0&q=CDI"" target=""_blank"" rel=""noopener noreferrer nofollow""> 2 Stroke CDI Ignition Coil for your engine for the best results."
Michael Wolfe
Ethan take side cover off and see if the chain triangled inside gear case. More than likely that’s what happened.
Michael Wolfe
Ethan take side cover off and see if the chain triangled inside gear case. More than likely that’s what happened.
Michael Wolfe
Ethan take side cover off and see if the chain triangled inside gear case. More than likely that’s what happened.
Anonymous
“Hello…I am on engine number 2…The first was stollen. When I am peddling and release the clutch lever instead of it starting, it bucks a little and makes a roaring grumble. Even on big downhillss and if I stand up and peddle really hard and fast.
…How can I fix this?”
Anonymous
What is the oil mix for engines
Anonymous
Ive just fitted a new engine to mountain bike, run thru everything possible ie spark fuel air, but it doesn’t want to start this help is much appreciated
Anonymous
I only had my flying hores motor for 2 days and I fell in ever since the chain got stuck in I fell and it won’t start or get no spark to it
Anonymous
Hi, I just got a brand new 80cc engine 2- stroke, and i got the heading bolts to the right tightness and the carb is on tight, and everything is on right i am good to go but this is being saved just in case.
Anonymous
Hi I just built one of these and everything is put together correctly and it’s not starting I got spark compression I have the kill switch off i was able to go ahead and make sure there was no other issue found out that i had the CDI connected wrong lol
Anonymous
I have a question I have good compression I have good sport I have good gas flow I have no leak no air leak I have new spark plug new coil wire new piston new piston rings and all new gaskets but it will not start or even try to start the carbs good and everything but I believe I messed my timing up if my timing this can be a big issue so beware and be careful when installing
Anonymous
My engine was running fine then just bogged down all of a sudden i am not taking these mentioned steps
Anonymous
when I first put my engine on my bike it ran for about 2 weeks and now it won’t even start. Then i talked to bike berry and we found out together that my carburetor was flooded they replaced the float and i was on the road again (willie nelson voice)
Anonymous
My bike is awesome good things going on for bike berry
Anonymous
I have been running my motor now for a good month and i have no complaints.
Anonymous
2 brand new cdi’s & magnetos’ , n spark plug, …. magnetos’ check in at 336-342,, Cdi’s check in at 0.00 CDI was changed and i was good to go
Anonymous
I hav a 2 stoke on my push bike with a 44t sprocket was running good I changed to a smaller one 30 something teeth
Anonymous
Hi I got 80cc kit on bicycle going great.
Anonymous
My bike has run fine for a year now, and i have not had many issues with it. All you really need to do is take care of it and make sure you are on the replacement parts and giving it rest in between well money spent.
Anonymous
I have a bike was runing like a dream
Anonymous
Hi Bikeberry you rock!
Anonymous
My 49cc motor free wheels with clutch engaged and disengaged. I took the clutch cover off to see inside. I adjusted pressure plate and clutch arm.. Still having same issue. Could the drive gear bearings be bad?