Small sprocket won't turn

M

motorbikerider

New Member
I just completed my first build, however the small sprocket is seized up for some reason. I haven't put fuel in it or tried to test drive it. I tried walking it forward and the back tire drug and eventually the chain came off. The instruction manual says you should be able to turn the sprocket by hand easily and if it is stuck try wiggling it back and forth gently. That didn't work, I'm sure there is someone on here that has a good answer for me, i've already learned alot on here.

Appreciate it,
Motorbikerider
usflg
 
Well - first off the "manual" is full of **** - you'd have to have thumbs of iron to turn that sprocket by hand on most of these. I've almost 1000 miles on mine and it's still a struggle.

First though - if your chain came off you have other problems, check your rear and front sprocket alignments and also if you have any offset or "wobble" in the rear sprocket - the rubber mounts are a pain to get just right. Another important one is to make sure your roller/tensioner is not only mounted properly and taking up all but about 1/2" of slack - but you'll also need to put it in a vice and bend it just a little so it's in line with the chain. If ya just bolted it on - it's lined up with the chainstay and not the chain itself.

Once that's all sorted, you can pull the spark plug out to eliminate compression resistance, then try turning the engine over again. You'll still need to be on the bike as it may skid anyway without any weight on it.

Some of these motors are a lil stuck when you get 'em - most are fine, they've just not been broken in yet and things are a lil tight. ;)

Good luck man - yer gonna love it when you get it done :D
 
My first build had the same problem. I pulled in the clutch lever and could not turn the sprocket ( with a large flat screwdriver ) without the engine trying to start. Mine was a clutch problem (since the motor should not turn over with the clutch lever pulled in...the clutch obviously wasnt working properly ) I took the 5 screws out holding the clutch cover on (opposite side from the chain drive) soon as it was off I saw fibers hanging out from between the clutch plate and the large ring gear. 1st remove the small set screw from the middle of the clutch pressure plate. 2nd pull the clutch lever in so youll see the clutch working, with the clutch pulled in you can loosen the center flat star shapen adjusting nut that the set screw you removed earlier was stopping from turning, adjusting might fix youre problem....unless it is like mine was....if so remove the center adjusting nut pull off the pressure plate and look for fibers or junk on the 15 rubber and fiber clutch pads...I had to trim fibers off of 2 pads myself ....reassemble check clutch adjustment replace the set screw and cover....and have fun. Oh yeah after the clutch was properly working I was able to turn the small sprocket with my fingers with some effort ...but turning it with the screwdriver was a breeze :) Just saw norms excelent article with pics and diagrams explaining the whole process in the sticky posts above youre post...good luck.
 
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First thing. Were you engaging your clutch by squeezing the lever? If so, you might want to start by tightening up your clutch cable. You can do this by loosening the scew on the clutch arm that is on your engine. The with a pair of pliers, tug on the cable and have a buddy push the arm a little tighter than before then tighten it all down again. Keep doing this until you can free up the rear wheel by squeezing your clutch lever.
 
Make sure at the end of the clutch pin, the ball bearing is still there. Also, like sojudave said, the clutch may not be pulling the cable hard enough. I have that same problem, and I got my mom to help hold some pliers while I pushed the clutch arm in and screw the little brass thing on. I had to push in in alot, so the clutch would pull the arm in enough for it to go in neutral. My thumbs were about to fall out! Also, use some good moly grease to lube everything up in there. I like valvoline multipurpose grease at Schucks.:-||
 
i install and service these kits into customers bike foe a side living.
recently i installed a 80cc and you could not turn the pedals, with/without the clutch in.
finally i removed the clutch hub from the motor and it was froze tight, you could not turn the inner hub even with a breaker bar.
i sent the complete hub to jim at CREATIVE ENGINEERING (the manic mechanic ad on the left side) and he replaced the cheap chinese berrings with hard steen ones.
i reinstalled it and it runs sweet.

stay dry
gubba
 
I recently got a motorized bike and don't know a great deal but I have a little problem the bicycle chain on the bike (not motor chain) is slipping of the sprockets because the rear sprocket on the opposite side of the chain motor is stuck and can't go forward. I can still start the engine and everything I just have to run to start if that makes sense but I can't pedal to start because of the rear sprocket being stuck... Any suggestions?
 
I'm not understanding what you are trying to describe, but it sounds like your clutch is not releasing.
 
The rear sprocket will not advance forward. Connected to the front sprocket with the pedals to where you hold down the clutch and pedal then release the clutch to start the engine. But I can't pedal to start the engine because the rear sprocket will not go forwards
 
sounds like either a chain problem in which it is stuck on the sprocket under that 3 screw cover, or a clutch problem in which the clutch isn't disengaging

take out the spark plug and if it doesn't move then, it's probably a chain problem
 
I'm sorry, I likely wont be able to help your issue but it seems there's some confusion about what you're trying to say. Please pick out which one closest describes your issue:

you cant pedal, but if you hold in the clutch on the motor, the bike can roll freely
I'd say it sounds like your pedal chain is binding, and has nothing to do with the motor.

You cant pedal, and even pulling the clutch handle the bike will not roll freely, but the motor will not attempt to start
the motor chain may be binding inside the case, which is usually an indicator that the chain is either not run in a straight line from the motor to the sprocket on the tire, or is simply too loose.

You cant pedal, and even pulling the clutch handle, the bike will not roll freely, and you can hear the motor trying to start.
your clutch may be the issue, check the clutch handle, and the arm (make sure the little screw thing is tight on the cable and pulling the clutch handle swings the arm, it should swing around 40-70 degrees when you fully pull the handle), If the bike still doesnt roll freely, then push the clutch arm until it touches the cable guide (this will take a lot of force the first few times, it's a pretty strong spring in there. Once you get it touching the cable guide it will stick there unless the bike is jarred rather hard or you release it yourself... watch out though, guide it back, it can snap back with enough force to smack the retention screw right off the cable). If the bike still wont roll freely at that point, take the sprocket cover off the motor and make sure there's a rod AND a ball bearing behind it inside the shaft in the center of the sprocket (it'll be slathered in grease so if you dont want to get your hands instantly soiled, wear gloves).

You CAN pedal as long as you hold the clutch handle in, but releasing it starts the motor and the pedals resist too much to move.
This is normal



Because from what I gather, you can push start the bike, but the pedals are jammed (first option).
 
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sounds almost like the motor is mounted so low that it is hitting the pedal crank

I'm thinking several pics will be needed to sort this out.
 
crassius said:
sounds like either a chain problem in which it is stuck on the sprocket under that 3 screw cover, or a clutch problem in which the clutch isn't disengaging

take out the spark plug and if it doesn't move then, it's probably a chain problem
Click to expand...
He said quite clearly that is was the bicycle chain.

I recently got a motorized bike and don't know a great deal but I have a little problem the bicycle chain on the bike (not motor chain) is slipping of the sprockets because the rear sprocket on the opposite side of the chain motor is stuck and can't go forward.
Click to expand...
Take it too a bicycle shop, your freewheel is messed up? Coaster brake?
 
Can't pedal the bike bike even without a motor chain on?
Is it a coaster brake bike? A Huffy Maybe?
It is your rear hub, already trashed coaster brake or it's not connected or perhaps when you put the brake arm back on you got the inner axle nuts too tight.

The point is just remove the motor chain from the equation and make sure the darn bike's back wheel works perfect before you even think of throwing motor power at it bud.

With no motor involved the back wheel should spin free, but if you grab it and try to push it back and forth it should not move.
 
sojudave said:
First thing. Were you engaging your clutch by squeezing the lever? If so, you might want to start by tightening up your clutch cable. You can do this by loosening the scew on the clutch arm that is on your engine. The with a pair of pliers, tug on the cable and have a buddy push the arm a little tighter than before then tighten it all down again. Keep doing this until you can free up the rear wheel by squeezing your clutch lever.
Click to expand...

Over 8 years later, and this got me the answer I needed. Try the easiest thing first, right? I’m working on my first build. Bout to fuel her up, now that I got this issue sorted. Thanks!
 
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