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Shorte01

Need Help with Chain Slack

13 posts in this topic

So I just swapped out sprockets and the new one is a little larger. The problem comes when I try and adjust the rear axle placement to get the right amount of tension in the chain. I can get it just where I want it when I'm not sitting on the bike, but the second I put a load on it the chain tightens up really good. So I go ahead and move the axle forward to a position where the chain has the right amount of slack when I'm on the bike. Then whenever the bike is unweighted there is a gross amount of slop in the chain. So the question is how can I find a happy medium so that the chain isn't extremely tight when I'm on it and isn't really sloppy when its unweighted?

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Uhhh, split the difference? Chain tension is checked with no one on the bike.

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If I can fit 3 fingers under the chain at the end of the slider, then i'm happy. That is usually the happy medium for me anyways. Then I put a screwdriver on the rear sprocket and turn the tire untill the chain tightens up a bit, then I tighten the axle nut. I find if I do this, the chain wont tighten up on me when I tighten the axle nut. I doubt this is the professional way of doing it, but its always been the perfect formula for me.

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The manual states 1.4-2 " inchs at the end of the swing arm chain slider,with weight off wheels. Adjust it there and leave it yhou should be fine

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Weight off the wheels is the important part. As in on a stand. The lower roller will pick up the chain under that condition. Set it per the manual, it works.

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The best and most accurate way to adjust a chain is not by the manual

You need to have bike on the stand

Remove lower shock bolt

Raise the rear wheel up to where the countershaft,swingarm bolt , and rear axle are all lined up

At this point in the travel will be where the chain will be the tightest

adjust your chain here with @ half an inch slack

reassemble and your set

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Yamaboy's method makes logical sense, as the ultimate goal is to ensure you have just enough slack at the tightest point, however, it seems like too much work.

I follow my manual and allow 1.6" - 2.0" of slack measured from the top of the rear slider bolt to the bottom of the chain when the bike is on a stand (no weight on the rear tire). This is for my 2000 YZ26F. This is essentially the same as "mayday" except he listed 1.4" as the lower spec limit.

This is Yamaha 's setting...and therefore is trustworthy. You don't need to go through the extra work Yamaboy described. It shouldn't take more than a couple of minutes of work.

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Follow the manual, you cannot go wrong. Remember rotate the wheel and set the slack when the chain is at the tightest point (the slack will chagne as the wheel rotates).

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jeremiah is right I went back to check in both my 02 426 & 04 450 both manual states 1.6-2.0

1. elevate rear wheel by placing the suitable stand under the engine

2. check: chain slack

above the seal guard installation bolt

out of spec's-> adjust

note: before checking and/or adjusting, rotate rear wheel through several revolutions and check slack several times to find the tightest point. check and or adjust chain slack with rear wheel in this "tight chain" position. :)

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whatever way you do it,make sure the sprockets line up. the adjustment marks are just there for show because they don't line up!! i take a 1' ruler and use it as a straightedge down the chain off the rear sprocket,and eyeball it(make sure the chains pushed to the sprocket so its even). mine's off about a 1/4" by the marks! :)

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put the bike on a stand. the rear tire should be off the ground. i set it so i can fit my index and middle fingers on end in between the end of the chain slider and the chain. i don't know if spring sag or rider weight comes into play, because my bike does'nt sag very much, and i only weigh 160 lbs. but i believe this should'nt make a difference, as setting it this way is taking into account the full range of motion of the swingarm. ??

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whatever way you do it,make sure the sprockets line up. the adjustment marks are just there for show because they don't line up!! i take a 1' ruler and use it as a straightedge down the chain off the rear sprocket,and eyeball it(make sure the chains pushed to the sprocket so its even). mine's off about a 1/4" by the marks! :)

The easiest way I've come up with is to measure from the axle center to the same point on each foot peg. It's a straight shot on each side.

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my footpegs take such a regular beating it wouldn't be a consistant measurement for me! :) the ruler trick is very simple :)

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