micargi puma chain problems... can I do this ?

A

abefroman

New Member
Micargi puma is almost finished. I was using a spring chain tensioner but the chain kept skipping a tooth at the drive sprocket - jammed up at 20mph. luckily i just skidded to a stop. then it did it again 2 more times.

I have two of the standard chain "tensioner' wheels that I am using as guides to keep the chain located between the wheel and the frame. the top wheel in the picture does that. the bottom guide keeps the chain under the frame. I was using the spring chain tensioner, but I'm re-doing it to omit the spring chain tensioner. obviously I'm not using the chain wheels exactly how they are designed to be used.

do you think the top stationary chain guide might be the problem instead of the spring tensioner ? does the top chain need to be a direct pull straight from the rear sprocket ?

I got rid of the spring chain tensioner but haven't tried it on the road yet. check out the pics
 

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Be aware any roller on the top of the chain run MUST be solid as a rock! All the pressure is on the top when under power and ANY deflection can cause issues. If possible, try running with the top chain run straight from sprocket to engine. If you must run a roller on top, be sure it's a STRONG roller and mounted securely for strength. From the look of the pics, your roller mount seems clamped to the frame ratherr than welded. I fthis is the case, try welding the mount solid to prevent ANY deflection at all. This may help.
Also, is the sprocket running dead true and centered? Any misalignment here will have bad effects on chainline reliability.
 
We can't tell from your photos but the drive and driven sprockets MUST be in line with each other. If either of those tensioner wheels are pulling the chain off to the side you'll have problems. The same if the sprockets aren't aligned. The chain has to run in a straight line. It will not run at an angle.

As Maniac57 said, the top chain is under a lot of stress when the engine is pulling the bike. You need to get rid of that top tensioner, or as he said, make sure it can not move and is aligned perfectly with the chain path.
Roller chain drive systems rely on alignment of the sprockets and proper chain tension. If either isn't right you'll have the issues you describe.

Tom
 
You have a lot going on there with the chain path! I would be tempted to use a idler sprocket with high speed bearings on the top, from what I've learned from industrial maintenance is for long life of chain and sprocket you need maximum wrap or more contact to the gears. If the chain is not at sharp turn it helps also.
 
Can the engine be mounted lower?
would that give you a straight top chain run?
Those Idler pullies stuff up pretty quick with drive load on them.
Looks to me the motor will go lower, May just need to change the exhaust?
 
abeforman: Nice build none the less. Looks good in black. Mine is red. Yours looks great!

Like to think I live in the far north west corner of Louisiana, because I was born in Shreveport and now reside in Washington State, the far far north west corner of the Louisiana purchase... thus I have not actually left home living here. And I do see you are from New Orleans.
 
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