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Discussion Starter · #1 ·
Cliffs:
- Adjusted chain slack from 25mm to 20mm before I realized 25mm was ideal midpoint, not max. Oops. Used torque wrench on axle nut so I wouldn't overtorque it (RTFM this time).
- Bike then had groaning sounds and strong vibes under decel in the right rearset up to about 40 MPH.
- Readjusted tension back to ~25mm and backed off torque a bit on the nut.
- Still get a light groan and vibe in the right peg but only around 25MPH -- any slower or faster it goes away. Sometimes goes away after warm.
- Eyeball alignment looks OK; no weird pulling/turning; no visible swingarm damage.
- What'd I break?

The other day I measured the slack in my chain: movement up + movement down from midpoint rest equaled 25mm while on sidestand, level ground. Reading the swingarm sticker, I thought I was at the limit and figured I'd tighten it up a bit. Up she went on the rear stand, I loosened the axel nut (thank you PVC cheater bar), loosened the lock nuts and tightened the adjuster nuts equally. I double checked this by making sure both axle nut alignment markers were the same, and triple checked by measuring from each axle nut bracket to the end of the adjuster "window". Quick lockdown of everything so it wouldn't shift when I moved the bike and proper torque on the axle nut via a torque wrench.

After putting the bike back down to check the tension change, I RTFM and found out 25mm was the recommended tension between min and max specs. Oops. My new tension was right at the 20mm minimum and I didn't have time to readjust, so I figured I'd tweak it again the next day.

During my ride to work, the bike made some pretty gnarly groaning sounds while slowing from 40+ MPH with vibes in the right rearset. I didn't feel any pulling or affects during turning. I don't recall hearing/feeling anything during acceleration, only during deceleration.

The next day, I repeated the procedure but this time loosening the chain slack and retorquing the axle nut a bit less. It felt like it was harder coming off the second time than it was the first time. Again, verified tension on cold and warm chain was right around the 25mm spec. Everything was pretty much back to normal, but I still get a light groan and some minor vibes at 25 MPH, +/- 5MPH but at no other speed. It seems to kinda go away as the bike warms up, however, but I can still hear it a bit at times. I'd never hear it if I happened to be wearing my earplugs. Again, no odd pulling, wheel spins freely.

So...what could I have messed up if tension and torques are in spec? Alignment seems OK, and I'd figure the rear brake disc rubbing would cause vibes across the entire bike at multiple speeds. I don't see any bends in the swingarm, and again I'd assume that would cause continual vibes/sounds. I never removed the wheel, axle, or bearings and don't think I torqued the axle itself. Though if I overtorqued something along the way I suppose I might have damaged a bearing or something.

And of course this morning the bike stalled right after I started it, just like it did before my first service when my valves were all outta whack. And it hasn't even been 2000 miles since my last service yet :/
 

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What you heard & felt was simply a tight chain tention & the chain not running smoothly on the front sprocket. Even at 25mm you will still have a little of this, and it does not run completley smooth until about 30mm.
25mm is the correct setting and gives you the best over all feel. Less jerking on throttle opening and closing through the transmission. The other mistake people make when tentioning chains to is they force the chain up & then down to check the play. Don't force it, just lift it up lightly and drop it back down to check.
 

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Did you check for the tightest spot on the chain before setting the adjustment? There may be significant difference between the loosest and tightest spots on a chain. Always set the tension at the tightest spot.

Having too much chain tension puts stress on the countershaft. It's better to run a tad loose than too tight.


Jay
 

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Discussion Starter · #4 ·
What you heard & felt was simply a tight chain tention & the chain not running smoothly on the front sprocket. Even at 25mm you will still have a little of this, and it does not run completley smooth until about 30mm.
25mm is the correct setting and gives you the best over all feel. Less jerking on throttle opening and closing through the transmission. The other mistake people make when tentioning chains to is they force the chain up & then down to check the play. Don't force it, just lift it up lightly and drop it back down to check.
Gotcha. I always had pretty loud chain rattle on the guide, but never the groaning. I'll try to make sure I'm not forcing the chain when checking play. I might have a tendency to do that. The 25mm bit threw me since on my Multi, the slack is merely indciated in the distance from the swingarm rather than actual freeplay so it's simply plop a tape measure on and look.

Did you check for the tightest spot on the chain before setting the adjustment? There may be significant difference between the loosest and tightest spots on a chain. Always set the tension at the tightest spot.

Having too much chain tension puts stress on the countershaft. It's better to run a tad loose than too tight.


Jay
I decided to adjust the chain after several measures over a period of time were consistent at 25mm, but not at once. I do period spot checks but only at one point in the chain unless I notice something off. If it's been a while I'll do several checks. So far the CBR was 100% consistent over its entire life with the 25mm freeplay. I just bungled and thought that was the limit :p I did a few checks after the first adjustment, but I can't remember about the 2nd. I was trying to beat the sunset on the second adjustment.

I have a bit of a trip coming up (if I get lucky I'll get some good video/photos and get to review some new luggage) and some mods to install on the Multi, so I'll double check tension and see about slacking it off a bit. The righthand portion of the axle was really resistant to moving on slackening the chain, so I might have to get a little...pursuasive to slacken it out more.

Thanks all for the info.
 

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The sound you can hear is the damage you've caused to the gearbox output shaft bearing, from running the chain too tight. It could be OK for the rest of the life of the bike, but it won't go away and it won't get any quieter, it may get noisier in time. When adjusting your chain, it's always best to err on the slack side, to prevent this sort of thing happening.
 

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Greetings kamikazekyle,

Did you lube the chain before checking the chain slack ?
 

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when you need to adjust the chain looser, I go way loose evenly, kick the tire forward, then light snug on the axle nut, and bring the tension back up evenly on each side until you get 25mm. torque the axle nut.
 

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Discussion Starter · #8 ·
The sound you can hear is the damage you've caused to the gearbox output shaft bearing, from running the chain too tight. It could be OK for the rest of the life of the bike, but it won't go away and it won't get any quieter, it may get noisier in time. When adjusting your chain, it's always best to err on the slack side, to prevent this sort of thing happening.
Quite certainly could be damage. I do know the effects greatly diminished after the 2nd adjustment, and were even less the last time I rode (no sound, just a little vibe). So perhaps I was lucky and there is no permanent damage. Could damage to this bearing create vibrations in the right peg but not the left?

I would err on the side of loose -- which I normally do -- but mistook the 25mm spec on the swingarm for the maximum out-bound spec. After I actually read the spec in the manual after adjustment, I realized my mistake which put the chain at bare minimum spec. The tire spun freely in testing, so I let it stay at minimum spec on my ride to work. I didn't notice the sounds until I hit higher speeds 1/2 way to work, which by then it was too late to really do anything about it. Anywho, best I can do now is make sure the chain is in spec and see if the engine eats itself.

Greetings kamikazekyle,

Did you lube the chain before checking the chain slack ?
Nope. I had washed the bike and lubed the chain the week prior, and didn't ride it that week. I put about 40 miles or so on the chain after the last lube before adjustment. The slack had remained consistent between spot checks for several months -- immediately after lubing, after degreasing, random check, etc.

when you need to adjust the chain looser, I go way loose evenly, kick the tire forward, then light snug on the axle nut, and bring the tension back up evenly on each side until you get 25mm. torque the axle nut.
Thanks for the tip. I'll keep that in mind. I did something similar when I loosened the chain on the 2nd adjustment, thought not to an extreme. I'm going to have to figure something out for the right side, though. It was a tough cookie to move on both adjustments. I'm thinking I might have to use some teflon, move the axel in the tire a bit, or something else.
 

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If you have a rear stand, I would adjust on the stand, final check on the side stand. a drop of oil on the ajust bolts may help, make sure the axle nut is not too tight, the adjusters have to move it.
you may need to loosen the axle nut, then take a mallet and tap it loose in the wheel, then snug it for adjustmet. wet riding and washing can stick the axle.

On some of our old dirt bikes there were no markings for the left/right chain adjustment. What we did is sight from the rear along the chain line, it should be pretty straight, its a good double check.
 

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Removing the chain guard and checking the chain with a laser pointer/leveler works well. You can run the focused light on each side of the chain and compare the divergence (if any) from straight. The guards never went back onto my bikes. :D
 

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Thanks to all replies,even though it wasnt my post, as I have had the same problem as well. I will try these solutions tmw and see how it works. It makes sense to lean towards looser chain than tight. just dont want to get it too loose
 
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