Chain rubbing cover

MadModder

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Feb 28, 2018
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Hey! I've been perusing these forums for the last month or two and finally got my first 66cc kit in the mail today so I figured I should finally join in. Anyway, upon mostly installing my kit(for the life of me can't find an Allen key to move my stupid twist shifters) and noticed the rear wheel will absolutely not spin by itself. At first I thought the clutch was stuck and read a few threads thinking we had the same problem, but upon removing both the cover over the magnets and the drive sprocket I am able to push the bike just fine without issue. With the sprocket cover/ clutch lever attached the only way my bike moves is if I turn the bolt on the magneto's rotor(or flywheel?) And slowly inch the bike around.
Inside the cover there's clearly a spot where the chain is making contact and wearing the paint down, that spot also makes it very hard to put the cover on on the first place. Basically I'm wondering if it's safe to just grind that bit the chain is hanging up on off and call it a day? My guess is that wouldn't really mess up anything, but I'm no mechanic.
Also its probably worth noting, at first I couldn't get the sprocket cover off at all, and feared completely stripping the screws, so I tried putting the chain on with the cover on and there was a metallic "pop" kind of noise that I just assumed was the chain forcing it's way through, but it got stuck right after so I ended up backing it out and shortly after I managed to get the cover off with a flathead and adjustable wrench and put the chain on right. Anyway, I'm not positive this didn't mess anything up, but the sprocket looks fine, and the clutch seems to engage and disengage fine still, it's just a matter of it hitting the wall of the cover.

So, any ideas if it's safe to just grind or file away the problem area? Thanks!
 


crassius

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Jul 23, 2012
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no biggie, you can remove some metal there with file or dremel, but I usually just cut straight down on either side of it with a hacksaw then grab that part with big pliers and snap odd a chunk - the better HD chains are a bit too fat for these covers
 

Frankenstein

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Jun 24, 2016
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You can grind it completely through safely, just go as far as the deepest cut groove and then a hair more, that would work well and it's been done a thousand times over by others who had the same problem.

If you have a hard time starting it make sure there isn't paint under the magneto preventing it from grounding correctly, if you have time sandpaper the black paint off at least 2 of the holes to help prevent a possible issue. Good luck welcome to the club.
 

MadModder

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Feb 28, 2018
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Thanks guys, I really appreciate the help. I ended up filing it down as mentioned and the bike rolls without issue, however it does still make something like a clanking noise while pedaling but it doesn't seem like there is resistance anymore, is that normal?

Also, I'll probably start a new thread but just figured I'd ask real quick, but my rear wheel has a very high spoke count (44 I think) so I can only get 6 of the 9 bolts in on the stock rear sprocket without probably damaging spokes. It's symetrical (probably not the right word) so everything is still balanced and able to be tightened down evenly, I just have a bolt missing next to every set of two bolts because of the wheels lacing. Is that safe to ride? Im considering a hub my sprocket kit, and already planned on buying different hubs and making a nicer set of 26 inch wheels instead of the 29s I'm using now then having my local shop true them, so I guess this is an excuse to do that sooner, but in the mean time is it alright to ride like this I should note that im a big dude, like 270lbs if that makes a difference.
Thanks again for the help!
 

Frankenstein

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How many spokes do you have? If you are using a wheel with too many or too little spokes the 9 holes don't line up with the gaps, you want 36 spokes, 18 a side. If you have that many then it's usually safe to loosen the ones you have and use a hammer to knock the other bolts in. Using only some of the holes puts the force from the engine on less spokes, so they break easier and explode while you are riding the bike.

The sound you hear is probably the engine turning over which comes with resistance. You might not have the chain tight enough and it's slapping something. Or the sprocket isn't square to the axle and the chain is hitting something else. Or your sprocket isn't symmetrical and the chain gets tight then loose and tight and loose..
 

crassius

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Jul 23, 2012
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newer master links often seem to have very long pins these days - the clicking you hear may be those pins going over the plastic roller on the tensioner - never seen that cause any problems

for a bad spoke count, I will loosen any spokes that get in the way of bolts and put a bend in them right there - get all bolts in and align sprocket well, then go back and put proper tension on the bent spokes - it is tension that is important not straightness
 

MadModder

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Feb 28, 2018
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How many spokes do you have? If you are using a wheel with too many or too little spokes the 9 holes don't line up with the gaps, you want 36 spokes, 18 a side. If you have that many then it's usually safe to loosen the ones you have and use a hammer to knock the other bolts in. Using only some of the holes puts the force from the engine on less spokes, so they break easier and explode while you are riding the bike.

The sound you hear is probably the engine turning over which comes with resistance. You might not have the chain tight enough and it's slapping something. Or the sprocket isn't square to the axle and the chain is hitting something else. Or your sprocket isn't symmetrical and the chain gets tight then loose and tight and loose..

I'm pretty sure they're 48 spoke wheels(I'll have to count when I get home), like I said, I'm a big dude, plus a bike that was 32lbs to start, my 270-290lbs depending if I have my backpack and what I'm wearing, plus the kit, I'm not sure 36 spoke wheels could even hold all that. Well, maybe a $900 set of wheels, but not what comes on a $150 bike. Also, I narrowed down the noise to the drive sprocket. It looks like there's some play in it so every time a tooth engages a link in the chain it makes a clicking or clanking kind of noise. It's much less noticable when riding compared to turning the back wheel in the air.

Also upon trying to start the bike for the first time I got nothing. I mean it sounded close to coming to life, though that may very well have just been me peddling. Unfortunately during this pedaling trying to get it started the threads on the one bolt on the tensioner stripped causing the chain to bunch up, and because of the wonky bottom bracket I needed to use until I could get a large enough steel plate made for my bottom bar, it yanked the engine sideways bending a couple links in the chain and bending my rear wheel a little -_- As you mentioned I sanded off some more paint under the magneto and tested to make sure I'm getting a spark, which I am but it's incredibly tiny(perhaps that's normal, idunno, I'm an electronics guy, this stuff is all so outside my wheelhouse), but now I'm kind of scared to even try starting it again until I find a shop to cut and drill me a more robust bottom mount bracket :/ oy vey
 

Frankenstein

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Jun 24, 2016
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Well first I'm going to laugh at the idea of 36 spokes might being not enough, hahaha. Sorry, if you just understood how much weight they could bear you would feel very differently, but since you have 48 you spread the torque from the sprocket even more evenly! Just use all the bolts and you won't set yourself up for problems.

Sparks generated at pedaling speeds (and slower) are generally weaker, but that's just how a generator behaves.

I'm having a hard time understanding what exactly is wrong with the bottom bracket that has something to do with the chain tensioner. You probably need a new chain unless you have enough spares to cobble it together, not really great to unbend one, especially the cheap stock stuff. Obviously replace the bolt and may as well replace the other 2 and give yourself a fighting chance.
 

Gregory Neighbors

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Feb 27, 2018
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I ran into the sam problem on mine, I used a cutting head on my dremel and cut that area out. It worked like a charm. My other issues on my first build haven't all been so easy to remedy. But I'm getting there.
 
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