Measuring Chain Slack

[joanna]

How exactly do you measure the chain slack? When I measure it to adjust it, should I have the bike on the center stand? the side stand? or should I have someone sitting on the bike?

thanks...

[earlfor]

Re: Measuring Chain Slack

Chain slack should be about 1" up and 1" down in the middle of the lower chain run when you are sitting on the bike and the bike is sitting on its tires.
Its pretty difficult to reach down to check chain slack accurately if youre alone. Most people put the bike on the centerstand and adjust chain slack.
However, slack is not the same with the bike on the stand and no rider as it is with a riders weight plus the weight of the motorcycle on the suspension.
The swing arm pivot and chain pivot points are different, so chain tension will increase with weight due to eccentric arcs. Anyway, to account for this, I set the chain slack with the bike on the centerstand, but add 1" in the up and down direction on the lower chain run. With the bike on the centerstand I set my chain with 2" of slack above and below, or put another way, I can move my lower chain run up/down a distance of about 4 inches. Once the bike is on its tires, that extra is gone and I am left with about 3/4 to 1" of slack, which is about as tight as you want a chain to ever be. The worst thing for a chain is being overtightened.

Earl

How exactly do you measure the chain slack? When I measure it to adjust it, should I have the bike on the center stand? the side stand? or should I have someone sitting on the bike?

thanks...

[Jethro]

I'm pretty happy as long as it doesn't hit the swingarm. That usually leaves me with about 1 1/2" of slack with me on the machine.

[earlfor]

Yep, thats one of my indicators. I run my chain with a lot of slack and if I hear it "tinking" on the swingarm when I gear down, I tighten it a wee tad.

Earl

I'm pretty happy as long as it doesn't hit the swingarm. That usually leaves me with about 1 1/2" of slack with me on the machine.

[KEITH KRAUSE]

Your manual should call for about 1" when on the centerstand.
I made a topic in the tips and tricks section called "the proper way to clean and lube your chain" that may interest you.

[earlfor]

I think the spec in the manual in this instance should be taken as a sugggestion of a starting point. For a lightweight rider of 100-120 lbs or so, it may be sufficient. It will not be sufficient for a 300 lb rider due to suspension loading. Also, chain tension should be set with the wheel at the tight spot after locating the "tight spot" by rotating the rear wheel. There will always be a tight spot and slack needs to be set at that point.

E.

Your manual should call for about 1" when on the centerstand.
I made a topic in the tips and tricks section called "the proper way to clean and lube your chain" that may interest you.

[KEITH KRAUSE]

Somebody needs to adjust the slack between yer ears Earl. :P

[earlfor]

Aw thats ok, I'll just keep getting my 20-25k miles on a chain and continue smiling. :-) :-)

Earl

Somebody needs to adjust the slack between yer ears Earl. :P

[SqDancerLynn1]

Most people run their chain too tight, Their is an easy way Get a shaftie

[earlfor]

Just as soon as I'm old enough to ride one. :-) :-)

Earl

Most people run their chain too tight, Their is an easy way Get a shaftie

[Road_Clam]

Aw thats ok, I'll just keep getting my 20-25k miles on a chain and continue smiling. :-) :-)
Earl

20-25K ???? chalking up miles while your bike is on the center stand doesn't count.

I learned from reacers, with respect to chain slack, all you need to do is get the swingarm "parallel" to the ground. This is the maximum swingarm pivot point at which the chain is stretched. Give yourself no less than 1/2" of verticle chain slack and you are all set. I totally agree, MORE slack is better. I have heard many cases of snapping cases near the sprocket output shaft from hitting a nasty pothole, chain stretches, and a 630 chain doesn't have a lot of "give" ans CRACK goes your engine case.

[kiwijetpilot]

I learned from reacers, with respect to chain slack, all you need to do is get the swingarm "parallel" to the ground. This is the maximum swingarm pivot point at which the chain is stretched.

Oh no it isn't... the chain is stretched the most when the output shaft, swingarm pivot and rear axle all line up. That may not be when the swingarm is parallel to the ground.

Also, hitting a pothole is HIGHLY UNLIKELY to damage your cases, unless you are using so little suspension travel that the three points mentioned above are not at, or beyond, the point where they line up with just your weight on the bike - or unless your chain is stupidly tight. Try it... with your weight on the bike, any further compression of the suspension should make your chain slacker, not tighter. At either extreme of travel, the chain will be at it's slackest. The ACTUAL effect of hitting a pothole could be to make your already-slack chain derail. Unpleasant. In addition, running a slack chain is hard on your transmission, cush drives and hub.

If you don't believe me, look at some motocross magazines and see how loose their chains get when the suspension is compressed... without chain guides, the chains would come off every time.

I doubt many racers would run with a slack chain, I used to race and trust me, chain snatch is your enemy (especially gassing it out of corners).

My .02...