Chain slack

[ryanschoebel]

My manual says that the chain should have between .6, and .8 in of vertical deflection in the chain. That seems a bit excessive to me? I feel like it should be tighter than that? does anyone have any issues running it with that much slack in the chain?

[oldktmdude]

   Better to be a bit loose than too tight. As the swingarm travels up during riding, the chain tightens up, so a bit of chain slack is required. Don't be tempted to over tighten. I am repairing  an FJ at the moment (not mine) that has suffered a broken chain and the picture is not pretty. Broken starter spigot, alternator mount lug broken from crankcase, sprocket cover mounting lugs broken etc. A tight chain is also not good for the output shaft bearing and seal.
   Regards, Pete.

[ryanschoebel]

Fair enough, good to know. i just fixed a whole mess from a broken chain, and im not eager to do it again. Thanks Pete!

[FJ_Hooligan]

Pull the lower shock pin and that will allow you to rotate the swingarm through the tightest point of the chain.  Make sure you have some slack at that point and you're golden.

I've never liked or trusted the "measure the chain slack" method because the necessary amount of slack changes depending on where you measure it and may be way different if you've raised the rear end. 

[Greg C]

I recently had a similar question when I was adjusting my chain. It seemed loose on the centerstand using the manual's specs. However, I noticed the tension changed quite a bit once it was on the side stand. I took a 1200/1300 mile trip and kept a close eye on it and had no issues with the .6 to .8 deflection.

My manual says that the chain should have between .6, and .8 in of vertical deflection in the chain. That seems a bit excessive to me? I feel like it should be tighter than that? does anyone have any issues running it with that much slack in the chain?

[ZOA NOM]

Loose chain is a happy chain. It's only pulled taught on top when riding.

[ryanschoebel]

Loose chain is a happy chain. It's only pulled taught on top when riding.

on top?

[FJmonkey]

Yes, on top. Think about the direction the rear wheel rotates. The front sprocket has to rotate so the top of the chain is pulled towards the front. So when accelerating the chain is tight on top and slack on the bottom. 

[aviationfred]

Too make life easier, buy a top quality chain. They require less adjustments during their lifespan.

I adjust my chain with another person close to my weight present. on the center stand, I make an initial adjustment. Take the bike off the center stand and have the other person get on the bike and put as little weight as possible on their feet, (max weight on the bike). I check the tension and adjust if needed.


Fred

[Pat Conlon]

Pull the lower shock pin and that will allow you to rotate the swingarm through the tightest point of the chain.  Make sure you have some slack at that point and you're golden.

I've never liked or trusted the "measure the chain slack" method because the necessary amount of slack changes depending on where you measure it and may be way different if you've raised the rear end. 

Hooli's point is most important.
Take the time, pull the lower shock bolt and articulate the swing arm. You only need to do this once just to get a reference on chain slack. You may be surprised.
If you have raised your rear end to improve handling, the angle of the swing arm in relation to the pivot shaft is different. You need more chain slack to compensate for when the distance between the c/s sprocket and rear sprocket gets longer when the swing arm angle compresses to horizontal.

Just sitting on the bike may not be enough to compress the swing arm to horizontal, the longest distance between sprockets, the point where the chain will be the tightest.

When in doubt, remember Rick's advice: A loose chain is a happy chain.

[Motofun]

When tech'ing bikes at the track the most common fault I've found is a "too tight" chain.  This is serious bad ju ju.  If the the chain slack is lost it restricts the suspension and you end up riding a hard tail.  I like to see the chain free to move all the way up to the rubber bumper, perhaps 2 inches?  Watch the slow motion shots of the racers on TV, you'll see the bottom run of chain dancing around.

[balky1]

I've noticed that the info in Clymer manual is way off. It says that 1-2 cm of slack when on center stand is enough, but that is far from truth. I've listened to the advice from forum, disconnected the rear shock  and found out that a slack of 3-4 cm when on SIDE STAND is enough to have a bit of slack when it is in its tightest point of travel.
After I've put a new chain it seemed to me that the chain stretched too much and I've retightened it. Chain acquired the same amount of slack after a short time. That was an 'aha' moment and I left it like that. Slack hasn't changed for some 10000 km now.

[ryanschoebel]

Hooli's point is most important.
Take the time, pull the lower shock bolt and articulate the swing arm. You only need to do this once just to get a reference on chain slack. You may be surprised.
If you have raised your rear end to improve handling, the angle of the swing arm in relation to the pivot shaft is different. You need more chain slack to compensate for when the distance between the c/s sprocket and rear sprocket gets longer when the swing arm angle compresses to horizontal.

Just sitting on the bike may not be enough to compress the swing arm to horizontal, the longest distance between sprockets, the point where the chain will be the tightest.

When in doubt, remember Rick's advice: A loose chain is a happy chain.

Sounds good. Im not entirely certain how to do it, but ill do some research, and figure it out. Thanks!

[CutterBill]

And just to be technically correct, chains don't "stretch"... they wear. If you had a chain with 114 links and each link wore only .001", then the chain will be elongated by .114". Which is a significant amount.  I suppose in the relative scheme of things it doesn't matter if we say "stretch" or "lengthen" or "wore."  But sometimes when you are facing a thorny technical problem, it helps to know exactly what is going on.
Bill

[FJ1100mjk]

If you had a chain with 114 links and each link wore only .001", then the chain will be elongated by .114". Which is a significant amount.
Bill

Not so significant when the chain is connected end to end and wrapped around two sprockets. Like one tick mark on the adjustment marks.