Chains What chain do you suggest

Discussion in 'Transmission / Drivetrain' started by mike93082, Mar 4, 2010.

  1. mike93082

    mike93082 New Member

    I just installed a Grubee 66cc engine and the chain that came with the kit snapped during the first ride and I figured that I made it to tight. Well I went to Walmart and bought a chain for a 1-3 speed bike for about 7.00 and left a little slack and was trying to get the bike to start by peddling with the clutch engaged from a dead start and after a short distance the chain snapped. Out of frustration I stored the bike away for the night.

    But I have read about different chains people use. What is the most heavy duty, strongest chain I can get that will fit the grubee 66cc kit? I basically dont care about price and dont care if I overkill on it lol.

  2. arkives1

    arkives1 Member

    Hi Mike,
    It sounds to me like you have a problem other than the chain, I don't know what it could be though. Something is surely placing an excessive load on your chain suddenly. These chains are pretty darn hard to break.Hopefully someone here will have an idea. Good luck!
  3. AussieSteve

    AussieSteve Active Member

    Mike, there's already a thread going on about chain selection, immediately below this one.
    No need for another, it gets confusing to all. Refer to that for actual chain selection.

    As Woody says, you've got bigger troubles than merely chain selection.
    A better title for your thread might have been 'Chain keeps breaking', or similar, to get appropriate responses.

    Now, I'll get off my high horse.
    In your last thread on this subject, I asked if you could post pics.
    The question still stands. Something really is wrong, there. I've never seen a chain break. Something is catching or drastically off-centre.
    Set it up and, before starting it, set it on a stand or get a helper and try to figure out what's going on.
    If you have slack in your chain, it can bunch under the countershaft cover and jam. This might be your problem. Also, some countershaft sprockets simply don't work, it seems.
    Are there marks of the chain catching under your countershaft cover?

    N.B. To set your chain tension properly for these things, turn your back wheel until the chain is at it's tightest, then adjust for virtually no slack without making it tight.
    Normally, 10-12mm is OK for other chains, but on these you need an absolute minimum.
    Take note of just how much the chain loosens and tightens as the rear wheel turns. If too much, you might need to loosen and re-position your rear sprocket slightly. Also ensure that you have a slight twist in your tensioner to make it parallel to the chain and that it's clamped really well.
    Last edited: Mar 4, 2010
  4. Fabian

    Fabian Well-Known Member

    This is the 415 chain i would recomend - it's an o-ring chain, significantly reducing chain stretch, not to mention that it's a top quality item.

    Attached Files:

  5. mike93082

    mike93082 New Member

    The chain I was using is the Bell chain from Walmart and I noticed a few people say that is cheap, garbage chain.

    I find it odd that it broke myself. I did spin the rear tire and it has so little wobble that there is no way that is the cause. I am talking that if I put a pencil there to mark it it would leave almost no marks.

    I do have another chain I am going to try tonight. But however I did notice with the existing chain before it broke I would turn the wheel with the clutch disengaged and it would get slack then get tight and so on.

    I am thinking about ordering 415 chain or chain for a motorscooter for something like 35.00.

    I will post pics once I get home tonight.

    But can anyone tell me why as spinning the wheel it would be slack on bottom and tight on top and then vice versa once the wheel was turned.
  6. Dilly Bar Rob

    Dilly Bar Rob Member

    The rear sprocket is most likely off center, like Steve says try taking it off and re-positioning it. If you had to grind out the hole in it so it would fit on your hub make sure that the hole is ground out perfectly centered, if necessary make it a bit bigger. If no grinding was necessary still make sure that the hole is centered in the sprocket, we all know just how "tight" those factory tolerances are :D

    If you are 100% sure that the sprocket is centered and the chain still goes tight/loose then it could be because of -

    1- teeth on the sprocket (either one) being "off" - I had a rear one that I could not get to stop doing this, upon closer inspection I found that teeth on one side of the sprocket were actually not as deep as they were on the other side....

    2- countershaft bent - I believe that this is why the chain on my folder bike goes tight-loose ever so slightly. Seems that the countershaft must be bent a hair (has done this since new) as I can see the small sprocket wobbeling around, I can see the clutch doing the same thing when I have the cover off.

    3- chain could be trying to jump off/not sit properly on a certain tooth. I file the teeth on the rear sprockets to make the tops round. This helps a LOT, also makes the chain drive a lot quieter. It might be a good idea to do the same to the small sprocket as the teeth on it are just as sloppy, however I have not found this necessary (so far).

    Also don't forget that when pedal starting the bike there is a big load on the chain tensioner (as the slack side turns into the the tension side when doing so), if the tensioner moves (twists) even just a hair it could cause the chain to jam (and break). Make sure it doesn't move at all, I had this problem on my last bike, solved it by tack welding the tensioner to the bike :devilish:

    The smaller the rear sprocket you use the less pronounced this problem is because of the sprockets smaller diameter - example: a 36 tooth sprocket will make the chain loosen-tighten a lot less even when it's off center compared to a 44 tooth. The bigger the sprocket the better your centering has to be.

    Hope this helps, Dilly Bar Rob
    Last edited: Mar 6, 2010
  7. AussieSteve

    AussieSteve Active Member

    Generally it won't do exactly what you describe, it will just get tighter and looser overall as the wheel is turned, rather than alternating tightness between top and bottom.

    When I centred my original sprocket, I turned the wheel until the chain was at it's loosest and adjusted the chain slightly tight, then turned the wheel until the chain was at it's tightest to put some tension on the sprocket.
    All I had to do then was undo and re-tighten the sprocket bolts and chain tension pulled it into place. Worked well and took away almost all of the off-centre problem.
    Rob makes a good point regarding the hole in the sprocket. You might need to file it slightly to allow the sprocket to centre, if it's already hard against the hub.
    Last edited: Mar 6, 2010
  8. danlandberg

    danlandberg Member

    Front sprocket. I had a binding problem when moving the bike backward. noticed a tighten loosen top then bottom of chain, but did not have the problem pushing forward or riding. I did not do any filing or grinding on any thing.