chain binding up on engine

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jbabb

jbabb

New Member
Aug 3, 2009
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Please Help!!!!!

My son and I are on our second build. We decided to put anti vibration motor mounts on it,(similar to those described on this forum). We also fabricated a new Idler mounting bracket.

That said, It runs great. occasionally, when the clutch is released and re-engaged, the chain seems to bind up on the engine sprocket (inside the cover).

I look down the chain ( cheap Chinese chain), it is not exactly straight. it has a few waves in it. Could this be the problem.

As near as I can tell the chain, engine sprocket and wheel sprocket are in-line. Could the engine be moving enough sideways to cause this to happen. It does flex slightly to the sides due to rubber mounts.

Can anyone give a couple of dumb grease monkeys some advice?





Thanks,

Jbabb:-||
 
GearNut

GearNut

Active Member
Aug 19, 2009
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San Diego, Kaliforgnia
Engine movement is certain death for the sprocket alignment.
They need to be aligned as perfectly as the pedal chain. Sight down the chain like you are sighting down a rifle barrel. Pay attention to the angle where the chain contacts the sprockets. If you are fighting an alignment issue all ready, and the engine is moving around as well, then you can expect many problems.
Be carefull as the chain can get bound up in the sprocket cavity and blow out the engine case in that area.

Edit: Are the sides of the engine sprocket teeth slightly beveled in? They need to be or the chain can get hung up on the points and try to jump teeth.
 
Last edited:
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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it could just be too loose.

when you let off the clutch, the chain will "grab," and the top of it will tighten up, due to the pull of the engine, and the bottom of it will slacken.

this would cause it to jump upwards, possibly hitting the clutch cover, or it's trying to jump off the clutch cog.

also, it's hard to tell from the pictures, but your chain idler pulley looks like it's mounted kinda high. if there's enough slack in the chain, it might be catching an extra tooth on the clutch cog on it's way out towards the rear sprocket (like it wants to keep wrapping around it), and this could cause it to bind. if you could lower it, or mount it somewhere else, it'd put the chain on a different angle

i don't run the idler pulley on my chain, and it works way better. but i just might be one of the lucky ones who's motor lines up without it.

hope this helps, and good luck.
 
jbabb

jbabb

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Aug 3, 2009
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We think we may have figured it out, The engine was a bit out of alignment., So we have it adjusted straight now. and the chain is rolling over much smoother than before, ( up on the stand at least, before it was binding even on the stand.) Tommorow I will find out if that has fixed the problem or not.
 
jbabb

jbabb

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Aug 3, 2009
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bairdco said:
cool.

make sure you pay attention to your motor mounts. anything not bolted solid is gonna want to move. keep your wrench handy when you go riding...
Click to expand...
The mounts are fairly stiff, and the rubber could be tighted down yet. It tilts slightly sideways when you pull on it by hand. But doesn't seem to move much when running the bike. Other than that, the mounts havent really shifted yet ,I dont them expect to, I just had the front one adjusted crooked from the beginning.
 
Kevlarr

Kevlarr

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Jul 22, 2009
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#41 chain is much more forgiving to a slight misalignment and is a WAY better chain overall. Switched mine because the master broke and it was faster to go buy a new 10' length from Tractor Supply, so for $16 I basically have two chains now. After putting 70 miles on the new chain it hasn't stretched one bit. I'll never use the #415 chain that comes with the kits again.
 
jbabb

jbabb

New Member
Aug 3, 2009
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I will try to lower the idler. I guess I haven't thought of that. I can remove a link or two and lower it. Either way it shouldn't hurt it (higher or lower).

Thanks for the info.

jbabb
 
jbabb

jbabb

New Member
Aug 3, 2009
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usa
Think We solved our problems Thanks everyone.

We lowered the idler, shortened the chain, Put on a new chain and re-aligned the engine. One or all of those seemed to work!

Jbabb
 
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