Chain/Sprocket seizing

MediocreBikeMan

New Member
Sep 16, 2019
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I have an old beach cruiser I’ve been riding for a month with the “80”cc bike engine kit attached. Let me be clear, my alignment and chain size are fine. The engine also runs smooth as butter. The problem started two days ago and it started as a light squeak which goes away after running the engine but then started to become more aggressive, keep in mind that this happens while coasting and until now didn’t happen with the engine on. Now the chain is seizing and I could barely get home because I didn’t want to stress the engine. I’ve narrowed the problem to the front sprocket and it is now squealing like a pig and is locking up, any idea what this is or how to fix it?
 

allen standley

Well-Known Member
Oct 22, 2011
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Bangor, Maine
front sprocket and it is now squealing like a pig and is locking up,

Should be a shaft key there behind the nut and washer. be sure it's not sheared. Also pull the big cover on right side (5 screws). Check the bevel gear driving the clutch, also a shaft key there behind the big screw and toothed washer. That squeeling sound usually is from the bevel gear screaming for inspection. If all is fine and tight put a small small dab of grease in between the gears. Be careful, too much and it will get in your clutch= Bad.
 

MediocreBikeMan

New Member
Sep 16, 2019
4
0
1
21
front sprocket and it is now squealing like a pig and is locking up,

Should be a shaft key there behind the nut and washer. be sure it's not sheared. Also pull the big cover on right side (5 screws). Check the bevel gear driving the clutch, also a shaft key there behind the big screw and toothed washer. That squeeling sound usually is from the bevel gear screaming for inspection. If all is fine and tight put a small small dab of grease in between the gears. Be careful, too much and it will get in your clutch= Bad.
All is in check, problem proceeds to exist. There’s a lot of catch and clicking when moving backward, also it’s quite loud. I don’t see how the bevel has much to do with this since it happens while coasting.
 

allen standley

Well-Known Member
Oct 22, 2011
1,118
218
63
Bangor, Maine
If you pull the clutch arm cover and inspect for chain gouging that may be the answer to your grinding sounds. You can take a dremmel tool and try to smooth out a better chain path.
I don’t see how the bevel has much to do with
Well, that big screw holding the bevel in is known to loosen and back out creating an unbearable squeel as it frictions on the backside of the cover. Raise the back wheel, take note of where the master link is in the chain, hand crank the pedals and see if it's the master link is catching up on the clutch arm cover, the motor and sometime if the engine angle is just right - the chain may be hanging up on the rear motor Mount Plate. rotate the crank and check clearences.
 
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MediocreBikeMan

New Member
Sep 16, 2019
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If you pull the clutch arm cover and inspect for chain gouging that may be the answer to your grinding sounds. You can take a dremmel tool and try to smooth out a better chain path.
I don’t see how the bevel has much to do with
Well, that big screw holding the bevel in is known to loosen and back out creating an unbearable squeel as it frictions on the backside of the cover. Raise the back wheel, take note of where the master link is in the chain, hand crank the pedals and see if it's the master link is catching up on the clutch arm cover, the motor and sometime if the engine angle is just right - the chain may be hanging up on the rear motor Mount Plate. rotate the crank and check clearences.
Thanks for the bevel explanation, The chain seems fine and the master link does not affect the clicking and it’s hard to locate the exact source of the squeal because it seems to fix itself over night then happen as soon as I ride over 100ft, then quickly progresses to many different scraping and squealing noises, I’m guessing this means it’s more internal. I’m really thrown off by the problem since there’s no visible wear of any unwanted contact.
 
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allen standley

Well-Known Member
Oct 22, 2011
1,118
218
63
Bangor, Maine
Do you think the clutch is slipping, could explain the squeal.. Remove the right side cover- remove the small phillips screw, grab and hold in the clutch arm, you should be able to turn that flower nut with fingers. Try turning it two notches clockwise. Watch this video first
I'm hoping to figure this out. I'm puzzled.
 

MediocreBikeMan

New Member
Sep 16, 2019
4
0
1
21
Do you think the clutch is slipping, could explain the squeal.. Remove the right side cover- remove the small phillips screw, grab and hold in the clutch arm, you should be able to turn that flower nut with fingers. Try turning it two notches clockwise. Watch this video first
I'm hoping to figure this out. I'm puzzled.
Good news is my clutch is properly fitted. also the squealing is much less but when I pedal you can feel and hear something catching aggressively then being smacked back in place with more rotation. It’ll be smooth and seem fixed for a second then abruptly stop my back wheel sending me drifting before rolling normal for a few seconds again. It definitely has nothing to do with the position of the chain either. Problem progressed, I can move backwards freely but I seize going forward
 
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