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  1. #1

    Question Bigger sprocket or chain tensioner?

    I need to vent some ideas.

    My rear fender is kind of a PITA. Due to how it's mounted I had to use one extra link in my chain. That + that I use a 18" rear wheel instead of a 16" results in that my chain tensioning bolts in my plunger is to short. I can't get my chain to stretch enough, or if I pull one link, my wheel will be grinding on my rear fender front mount bolts at higher speeds (due to the rise of the tire, centrifugal power yada yada..)

    So. Which idea is the better one of these two? Pro's and con's are widely appreciated:

    1. A one or two tooth larger rear sprocket? (I know of the slight increase of rpm in high way speeds with this).

    2. A spring loaded chain tensioner (Š la Monstercraftsman style)? Costly, shipping alone is a fortune to me in Sweden and I'm in kind of a hurry since this is the only thing keeping me off the road (this + my registration inspection).

    What would ya all have done in my situation?

    Thanks, Stabler.
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  2. #2
    CB750 Addict Andy's Avatar
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    I guess the pros of the sprocket are a little more low end grunt and takeoff and solving your chain issue. The cons are the RPM and the gas mileage. I like the chain tensioner, but obviously the cost and time are definite cons. The pros would be a chain that is always at the right tension and a little less maintenance. I wonder if you could make one from a serpentine belt tensioner and a skateboard wheel? Maybe you could pick up a tensioner at a local boneyard or auto parts store.

  3. #3
    I was thinking of fabbing my own tensioner, but cant seem to find the f*cking clamp I need to hold it in place anywhere here in Sweden.. I've struck out on google as well. Skateboard wheels I've got a ton of (go figure) and the spring I could get. I could possibly even use a CB750 stock rear brake shaft spring in case I find no other.

    If I were to fab my own, what is so bad with doing a solid one? I mean without the spring arm? Just as long as you maintain the original amount of movement in the chain?

    Thanks, Stabler.
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  4. #4
    CB750 Addict Andy's Avatar
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    As long as it's on the bottom, I would think it would work. Would you adjust tension with your normal tensioner, or make some provision for adjusting it (the tensioner wheel) and locking it down?

  5. #5
    I'd use my original chain tensioner bolts, but leave enough room to adjust them again once the chain loosens up. This way also use them to keep the wheel in place.
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  6. #6
    And I could always turn the chain tensioner on the frame tubing it's mounted on to stretch the chain if necessary.
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  7. #7
    CB750 Addict Andy's Avatar
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    Have you ever seen the tensioner on the primary in a Harley? It's a real simple arrangement and you could possibly do something similar. With your bike not having a swingarm, does the chain tension change as the wheel moves up and down?

  8. #8
    Yup, it does. What Harley tensioner is it you mean?
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  9. #9
    CB750 Addict Andy's Avatar
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    It's just a slotted piece with a piece of some kind of plastic for wear. It moves straight up and down. I'll try and copy a picture for you out of my manual. It may not work because your chain tension changes with wheel movement. I think your idea of turning it on the tubing might be better.


    Click image for larger version. 

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    Last edited by Andy; 06-27-2012 at 01:33 PM.

  10. #10
    Thanks man!
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

  11. #11
    Moderator dirtdigger's Avatar
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    With a solid mount you will have to take into account that sprockets are not perfectly round and chain links wear uneven. If you rotate you wheel with the chain installed you will see it is tighter in some spots than others and looser in other spots, that is why the spring loaded tension is used. But with the frame not being rigged I dont think a tensioner of any type is really feasible because of the wheel movement. What are your sprocket sizes now? I would do a sprocket change if it was me. 1 or 2 teeth won't change cruising rpm all that much, yes it will change but its not huge. On a rigid the tensioner is an easy fix for chain tension but on a suspension rear end I dont think it is worth trying to figure out a way to make it work properly. IMHO

  12. #12
    Thanks dirtdigger. The thing is since I've got an vertical movement of my rear axle and not a radius movement (as is with a swing arm) I get different lengths between my sprockets when I hit road bumps and pot holes. That forces me to have more slack than usual so that I wont break my chain (or worse)..
    Everybody has a plan. Until they get a bee in their helmet.

    www.barndrunks.com

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