Trouble with chain tension.

[Mudshark]

I’ve discovered something strange going on with by

XR650R. it has variable chain tension…..

It behaves like the rear sprocket has a high spot on it.

Every 180 degrees the chain gets tighter…. The next 180

It’s loose again.

I’ve swapped out both back and front sprockets, one at a time

I have a stock set of sprockets as well as a range of rear sprockets

everything between 48 and 44 and a 15 for the front… it still

does it, no matter what sprocket combo I use. It must be the

positioning of the rear sprocket mounting holes… or something

I’ve spun the wheel, nothing looks like it’s bent or out of whack.

Well nothing I can see with the naked eye….

It’s not drastic, but if the chain is set Just right on the loose

180, it’s too tight with me on the bike…On the tight 180.

Before you say anything, go and check yours. I mean really…

Jack it up and rotate the rear wheel 1/8th of a turn at a time and

check the chain tension. I bet most of you have the same issue.

I’ve just marked the high spot on the sprocket and set the chain

tension with the rear wheel at the “tight” spot. I think I’ll run

It down to Honda and see what they make of it….. it can’t be

Good for the CS bearings etc…

needless to say, there are no seized links on the chain, it's nice

and clean and flexible.

[-=Jughead=-]

Maybe a long shot here, but...do you have a kinked chain? Or a link that is binding? Perhaps it only binds when being drawn arount the CS sprocket?

Measuring run-out ot he sprockets should be easy to do, and if they are uniform, then what is eft, but the chain?

Odd situation, no doubt...

[captb]

Mine is fine but I've had chains cause this many times, part of the chain is stretched, check runout on the sprockets first before replacing chain.

[Beyond The Pale]

Chains don't really stretch. They wear. The pins get worn which makes for play between the pin and the bushing. If each pin wears 10 thousandths and there are 100 pins then the chain chain is now 1 inch longer. The pins never wear evenly. That's what makes it different as you turn the wheels. This is even more so on an o-ring chain. When an o-ring fails and lets in some dirt, that pin starts to wear. Most of the other o-rings will be ok and those pins don't wear. This can cause what you are seeing.

[Max Power]

Chains don't really stretch. They wear. The pins get worn which makes for play between the pin and the bushing. If each pin wears 10 thousandths and there are 100 pins then the chain chain is now 1 inch longer. The pins never wear evenly. That's what makes it different as you turn the wheels. This is even more so on an o-ring chain. When an o-ring fails and lets in some dirt, that pin starts to wear. Most of the other o-rings will be ok and those pins don't wear. This can cause what you are seeing.

What he said.

[HawkGT]

I've found the tight-spot loose-spot syndrome to be a common occurence on all types of street and off-road bikes. It seems to me I've even encountered it on brand new chains and sprockets. I've always chalked it up to manufacturing tolerances (chain, sprockets, wheel).

[Mudshark]

HawkGT, I agree. The bike is new, it's got 2.500 miles on it. The chain

is still in good nick and the sprockets are all brand new.

I'll have to take it down to the local shop to get the runout on the sproket

and rear wheel checked though, I dont have equipment at home to do this

yet.... although, if I bought a Micometer and measure from the axle to the

roller surface on the opposite ends of the sprocket, it should show a small

difference.

Realize that the difference does not need to be big to cause this problem.

1 mm would be enough to cause the chain to go from slack to tight pretty

quick.

I've backed off the chain and it's better now, I'll see if I can pick up a cheap

Micrometer this weekend.... or just borrow one

The bike has always had a bit of a "chain slap" on the highway. I never figured

it would be this though. I must have checked the chain tension 100's of times

and never found it with the wheel stopped on the "tight spot" .... untill

yesterday.

[sorenlaf]

I’ve discovered something strange going on with by

XR650R. it has variable chain tension…..

It behaves like the rear sprocket has a high spot on it.

Bad/stretched/worn chain.

I've had this problem fairly often with my roadrace bike - hopefully, buying a better brand of chain will fix my problem; I'll no longer buy a bikemaster just because it's all that's in stock.

[HawkGT]

....hopefully, buying a better brand of chain will fix my problem....

FWIW, my DID ERV3 on my XRR has the tight/loose "problem". It's got less than 2000 miles of 50/50 riding w/ regular maintenance.

[Mudshark]

Bad/stretched/worn chain.

I've had this problem fairly often with my roadrace bike - hopefully, buying a better brand of chain will fix my problem; I'll no longer buy a bikemaster just because it's all that's in stock.

it's the stock chain, well maintained with about 2.5k miles on it. The bike

is used mostly on the street...

However, it is possible for it to be a bad chain... I'll check.

I only run RK or DID X / O-ring chains, I learnd that lesson a while back.

Thinking on this some more, it has to be the rear wheel.

The tightness always occurs when the wheel is in the same position, the

chain on the other hand advances around the sprocket, so the tight spot

would move if it were the chain. do you get what I mean??

[HawkGT]

...Thinking on this some more, it has to be the rear wheel.

The tightness always occurs when the wheel is in the same position, the

chain on the other hand advances around the sprocket, so the tight spot

would move if it were the chain. do you get what I mean??

That's some good sleuthing right there.

[-=Jughead=-]

That's some good sleuthing right there.

Yes, but if there is no run-out on the sprocket, then that rules out any elliptical-ness in that area.

[Mudshark]

That's some good sleuthing right there.

hehe! thanks. Well to rule out anything else, I'm going to replace both

chain and sprokets this weekend. If it still does it, it's the wheel / sproket

mounting holes that must be off a bit.... anyhow, I'll take it to Honda

for them to look at if this does not cure it.

I don't want to end up with premature CS bearing failiure, with my luck it

would happen right after the warrenty expires

[Mudshark]

Just a quick update.

I replaced the chain and sprockets. I got a sweet deal at Rocky Mountain MC,

Renthal 45 back, 15 CS, with a RK 520XSO 110 chain for $124 shipped.

They are all on the bike now and the chain tension is back to normal.

So it was just the chain causing it all..... I wonder how / why a chain would

do that uneven wear thing like that... It had less than 2.5K on it.

Anyhow, thanks for all the input guys.

[brichter]

the chain tension is back to normal.

So it was just the chain causing it all..... I wonder how / why a chain would

do that uneven wear thing like that... It had less than 2.5K on it.

Anyhow, thanks for all the input guys.

Pretty normal for any chain/sprocket that has any appreciable miles on it, that's why the manual always tells you to check the tension in several places.

[Mudshark]

Pretty normal for any chain/sprocket that has any appreciable miles on it, that's why the manual always tells you to check the tension in several places.

I don't class less than 2.5 thousand street miles as "appreciable miles".

The chain must have been defective.

[Mudshark]

Okay, I came back from a DS ride this weekend and the brand new

chain and sprockets are doing what the old set did.......

I checked them after fitting and after a 3-mile ride that set the chain.

Everything was fine.

I got back from the ride yesterday and washed the bike down, checked the

chain.... and it's doing it again!

Something is going on here and I have no clue what it could be... help!

It seems like the chain has uneven wear, causing it to have variable chain tension.

.... or like one of the sprockets has a high spot, causing the chain to tighten

up and at 180 degrees from that point loosen up again...

[HappyCurmudgeon]

I am only guessing as it seems to me it would be a worn chain, but...

Do the countershaft bearings check out ok? any slop or wobbles?

Wheel bearings check out ok? any play there?

Is the wheel/sprocket/chain aligned properly with the countershaft?

Is Venus in retrograde?

Have the appropriate sacrificial animals been offered up to the BRP gods?

[hypersthenos]

I've had the same problem on every chain driven bike I've ever owned. You simply cannot expect all chain links to wear at the same rate. The master link alone will stretch less than the rest of the chain. The best compromise I've found is to rotate the wheel to find the tight spot & then adjust the chain to the recommended specs. This drove me nuts as I am a bit of a perfectionist but I have not thrown a chain yet with this method. Just make sure the wheel does not rotate while adjusting the tension. Shaft drive would be no fun on a dirt bike!

[Mudshark]

I am only guessing as it seems to me it would be a worn chain, but...

Do the countershaft bearings check out ok? any slop or wobbles?

Wheel bearings check out ok? any play there?

Is the wheel/sprocket/chain aligned properly with the countershaft?

Is Venus in retrograde?

Have the appropriate sacrificial animals been offered up to the BRP gods?

Chain and sprockets are brand new 175 miles old.

The bearings are all 3000 miles old (mostly street use) with no

noticable play or wobbles.

As far as the sacrificial animals been offered... I ran over and killed a field mouse

and a Rat snake during the DS ride on Tuesday... does that count?

I've had the same problem on every chain driven bike I've ever owned. You simply cannot expect all chain links to wear at the same rate. The master link alone will stretch less than the rest of the chain. The best compromise I've found is to rotate the wheel to find the tight spot & then adjust the chain to the recommended specs. This drove me nuts as I am a bit of a perfectionist but I have not thrown a chain yet with this method. Just make sure the wheel does not rotate while adjusting the tension. Shaft drive would be no fun on a dirt bike!

I was beginning to think the same thing... I'm a bit of a perfectionist myself

that’s the exact reason why this bugs me, I've never noticed it on any of my

other old bikes before.... probably never paid close enough attention??

or none of them put out the power that this one does, so the chains didn’t

have to work as hard?

I have done as you suggested though and set it while at the tight spot.

It seems okay ... ish.

Thanks for the input guys.