Drivetrain Lash
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Thread: Drivetrain Lash

  1. #1
    Junior Member sp5russ1an's Avatar
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    Hello Everyone!



    I've been lurking around the forum for a while now, and you guys have influenced my decision to buy and build the bike into what it is now. (First bike, and first uild)

    The latest mod was a 15 tooth counter sprocket. I've been running the set up for about a month now. About a week ago, I noticed quite a bit of drivetrain lash.

    It's most noticeable in 1st or 2nd gears. When giving the bike, or coming off the throttle there is a bit of free-play between the engine and the rear wheel.

    With the bike off and in first gear, I can move the bike, back and forth, about an inch and a half (just over one chain link), before everything locks in.



    I was just wondering if:



    A. That's normal.

    B If not, would any of you guys have any suggestions as to what it coud be?



    Thanks,



    Chaga

  2. #2
    Senior Member Gerry's Avatar
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    Chaga, your drive-train set-up is pretty unique when compared to what most of us have. I understand that you referenced a period of a month, but I am curious as to what the bike was like before that. In other words, did you just recently add the long swing arm?. My first though is that in the last 30 days, your extra long chain has now had a chance to stretch. Now with a loose chain, before the bike can move (forward) the chain slack need to be removed (chain needs to be lifted or drawn tight). This condition would certainly be a lot more noticeable in first and second gear. Again just more guessing on my part. This situation will be more 'normal' for you than it is for me as I have a stock swing-arm and chain. If I am guessing correctly, a high quality or O-ring chain should help minimize the stretch that is creating this condition for you. It is also in your best interest to deal with this or be ever vigilant about keeping your chain 'properly' adjusted. Should your chain get too slack the chance for it to mis-align (for you) is much greater (my opinion). If a chain comes off at speed, the potential for bad things happening is pretty high. Stay safe........... Gerry
    Take care my Friend.........

  3. #3
    Senior Member lizrdbrth's Avatar
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    This is one of the potential downsides of extremely overlength swingarms that is seldom mentioned.



    Proper chain slack has changed due to your extended swingarm. There is only one way to re-establish proper chain slack and evaluate the safety of your overlength swingarm. It involves a bit of work, but it's also the method of determining proper chain slack employed by the guys who write the factory service manuals whenever a new model is released, and by the engineers who design bikes in order to determine how much swingarm is TOO much swingarm to run without a chain roller/tensioner:



    Lift the bike under the engine with a bike lift or something that permits a level, stable base.



    Remove the rear shock.



    Manually lift the rear wheel through its arc (If using a bike lift you can lower it gradually to accomplish the same thing). Find the point in the swingarm's travel where the chain is tightest.



    Adjust the snail adjusters just loose enough that the chain causes no resistence at its tightest point as you lift the swingarm through its arc. In other words just short of zero slack at its tightest point.



    Reinstall the shock and stand the bike on its kickstand under its own weight. Find a reference point of your own choosing somewhere along the swingarm's length. Anywhere is fine as long as it is repeatable and you'll remember it, but somewhere near the middle is generally easiest.



    Measure the slack at your chosen reference point. That is your ideal, perfect chain slack measurement, forever. You'll want to remain very close to the ideal adjustment at all times with a stretch that long. Your chain will develop far more slack than a stocker when at full extension or compression.



    Now put the bike back on the lift and allow the swingarm to drop to the point where the rear tire is off the ground. Pull the middle of the bottom run of chain sideways while rotating the rear wheel.



    If the chain can be made to derail from the rear sprocket as the wheel is turned your swingarm is too long to safely maintain proper chain slack. You'll need some sort of chain roller/tensioner. I'd even go as far as loosening the snails one notch and repeating the process. This will represent a bit of chain stretch and if there's any chance of a chain derailment if you get lazy with your adjustments you'll become acutely aware of it.



    If everything checks out and the chain cannot be made to derail at full extension, take the bike off the lift and rock it back and forth while in gear. You may find there is still excessive "belly" in the chain. If not, you're golden, but if you're still getting more than one link of movement before engagement your swingarm is simply too long, but not unsafe. You'll either have to learn to live with it, install a chain roller/tensioner, or a bit of both.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  5. #4
    Senior Member nfpgasmask's Avatar
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    Just reading through this thread. This is good info, lizrdbrth.



    Now, I am just finishing up my build, and I am having trouble getting the chain on. My chain came with my Beams long swing arm, so I know it is the right chain, but I cannot get it on. Its like 1 link too short to get the master link to slip on.



    So, after reading what you wrote here, I am wondering if I could get the chain on with the shock detached. I guess that would give me a little more play with my swing arm.



    Then, once on, I can adjust it following your steps above.



    What do you think?



    Thanks -Bart

  6. #5
    Senior Member lizrdbrth's Avatar
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    If you can't get it on with the bike at rest on the kickstand and the axle shoved all the way forward the chain is simply too short.



    Your swingarm swings around a pivot point (the swingarm bolt). As it swings through its arc the chain is tightest (rear sprocket furthest from the front) somewhere near the point where the swingarm is nearly level to the ground, or slightly before. The chain is looser anywhere above or below that point. If you remove the shock and lift the bike you may be able to get the chain on but the first time you hit a bump it will tear the input shaft right out of the bike, snap the chain or compress a few vertabrae when the chain locks up the suspension.



    The entire reason for posting the above procedure is to be certain the chain is loose enough at its tightest point to prevent this from happening.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  7. #6
    Senior Member lizrdbrth's Avatar
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    oopz.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  8. #7
    Senior Member nfpgasmask's Avatar
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    OK, thanks. Just seems weird that this chain does not fit. Is there anything I can check with my swing arm installation that maybe I effed up? I mean, I don't see how I could have, but....the chain was supplied with the swing arm, so I cannot see why it would be too short, but who knows.



    Bart

  9. #8
    Senior Member lizrdbrth's Avatar
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    You're putting a bit too much faith in your supplier. Or perhaps they assumed you'd use a smaller rear sprocket, er sumpin'.



    I'm told the standard rear sprocket may have been a 46T in some markets. Not sure about Japan.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  10. #9
    Senior Member nfpgasmask's Avatar
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    Quote Originally Posted by lizrdbrth View Post
    You're putting a bit too much faith in your supplier. Or perhaps they assumed you'd use a smaller rear sprocket, er sumpin'.



    I'm told the standard rear sprocket may have been a 46T in some markets. Not sure about Japan.


    Yeah, that's certainly possible.



    So, if that is the case, what are my options? Can I just get two chains, buy a chain tool and make my own chain? RisingSun suggested a chain tensioner, however I am not sure how those install and if that is overkill on my bike.



    From what I can tell, our chains are "428" chains. I'm not sure what that number means. I just counted links on the chain that came with the swing arm, and with the master link I am at 152. I cannot seem to find any chains that are even sold at that length or longer. I would guess I need like 4-6 more links to make this chain long enough to get on and adjust.



    This is pretty much the only thing hanging up my build so I want to get this sorted here so I can ride!! The bike looks pretty amazing now, nothing like a stock TW200!



    Thanks- Bart

  11. #10
    Senior Member lizrdbrth's Avatar
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    "428" is an industry size designation having to do with the width between the side plates and the distance between the pins. The teeth on your sprockets are laid out to match the spacing of a 428.Bikes use a variety of different sizes and strengths of chain and different thicknesses of sprocket depending upon horsepower, weight or lack thereof.



    Did the chain arrive in its original packaging, and can you identify it?



    If it's a common chain you can just obtain another and extend yours. A member here may even have a few links of unused chain. If you have a chain breaker you can take a link out of your old non-o-ring chain and install it into your non-o-ring chain as long as you use 2 non-o-ring master links. This will at least allow you to get the bike up until you can get some matching o-ring links.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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