Rear Chain Adjustment

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Lorenzo

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dear All,
I would like to check my rear chain and I am wondering how much is the slack I should measure at the centre of the chain run
please, note that I am doing it myself and I can't have anyone sitting on the bike while measuring. So I will do it on the centre stand and I guess the measurement may be different..
Do you think 3,5/4 cm should be right?
 
Aim for almost an inch of free play on unloaded suspension. To get in ball park of axle aligned square just pass a finger past front of tire and swing arms to get about same, then can go through the tedious routines of wheel alignment to try to see which way to do it in the future, especially away from home.
 
You don't say what model or year it is, but the 850 owners manual for 1973 says p26
it should be 3/4" to 1" (19 to 25 mm) of up and down movement in the centre of the chain run WITH THE RIDER SEATED.

I think you will have to explore what the difference is with and without the rider.
If you have it propped somewhere (with the handlebars against something),
it is possible to sit on it and get your fingers greasy jiggling the chain about.

It doesn't actually say if thats the top or bottom run of the chain.
I'd say thats the bottom run, the top run is almost inacessible up under the chainguard.
opethiselps.

It also mentions checking in various positions on the chain, in case one area is more worn than others.
It should always be adjusted so the tightest spot has enough play.
 
You need to compress the rear suspension so that the rear axle, swingarm spindle, and mainshaft are all in a straight line. This is the point at which the chain is tightest. Do this by either sitting with your weight back on the rear fender or by putting your chest down on the seat and pulling up on the swingarm with one hand while checking chain tension with the other.

To get a better idea what the FREE play is, put the bike in gear, roll it backwards, and then let out the clutch. This will transfer all the slack to the bottom run of chain. You need to check in a few spots as most chains develop tight and loose spots.

Eric
 
ewgoforth said:
You need to compress the rear suspension so that the rear axle, swingarm spindle, and mainshaft are all in a straight line. This is the point at which the chain is tightest. Do this by either sitting with your weight back on the rear fender or by putting your chest down on the seat and pulling up on the swingarm with one hand while checking chain tension with the other.

To get a better idea what the FREE play is, put the bike in gear, roll it backwards, and then let out the clutch. This will transfer all the slack to the bottom run of chain. You need to check in a few spots as most chains develop tight and loose spots.

Eric
Might I suggest a belt cinched around the swingarm and frame loop for convenience?
Ta.
 
I have used feed bags, bungee cords or racket straps when my myself to determine almost an inch chain flap slack unloaded is close enough and no measuring way to get chain sprockets inline quite good enough too. Carry on beyond this all ya like on Commando worship rituals.
 
very good way to assure wheel alignment when adjusting the chain...remember that the axle and swing arm pivot must be parallel. if it measures the same on both sides then the wheel is aligned. Because the swing arm pivot is inaccessible on the left side, I measure off the ISO pivot bolt. Having a big set of dividers helps.
 
You can use two cargo ratchet straps to compress your rear shocks to check chain tension if you are by yourself like Steve posted above.
Cheers,
Thomas
CNN
 
Lorenzo said:
dear All,
I would like to check my rear chain and I am wondering how much is the slack I should measure at the centre of the chain run
please, note that I am doing it myself and I can't have anyone sitting on the bike while measuring. So I will do it on the centre stand and I guess the measurement may be different..
Do you think 3,5/4 cm should be right?

Hi,

in the owners manual of my Triumph Bonneville ist stated 4,3cm (=1 3/4 in.) with the bike on the center stand. That works for my Commando as well (my weight is 70kg)

Ralf
 
Towner said:
Lorenzo said:
dear All,
I would like to check my rear chain and I am wondering how much is the slack I should measure at the centre of the chain run
please, note that I am doing it myself and I can't have anyone sitting on the bike while measuring. So I will do it on the centre stand and I guess the measurement may be different..
Do you think 3,5/4 cm should be right?

Hi,

in the owners manual of my Triumph Bonneville ist stated 4,3cm (=1 3/4 in.) with the bike on the center stand. That works for my Commando as well (my weight is 70kg)

Ralf

Thank you Ralf,
I feel this is the most practical procedure..
 
Once again Steve has hit the nail on the head. I adhere to the KISS principle as well. 1- 1/4 to 1 -1/2 inch free play when on stand is equivalent of 3/4 to 1 inch when loaded inline.
Some years ago I was in the pits at Pukekohe when a Commando was brought back in with its chain off. The mechanic had been asked by the rider to tighten the chain because of backlash. The mechanic said at the time that it was a wee bit tight. The result was the chain got thrown off.

A chain is too loose when it hits the buffers, until then, its not.

Dereck
 
During prototype testing, before the 1/4" chain was canned, we were doing adjustments every 150 miles or so. On a typical 500-mile day, that was twice while out on the road. After a chain broke on the high-speed test track and destroyed an engine, a 3/8" chain was made standard.
 
kerinorton said:
Once again Steve has hit the nail on the head. I adhere to the KISS principle as well. 1- 1/4 to 1 -1/2 inch free play when on stand is equivalent of 3/4 to 1 inch when loaded inline.
Some years ago I was in the pits at Pukekohe when a Commando was brought back in with its chain off. The mechanic had been asked by the rider to tighten the chain because of backlash. The mechanic said at the time that it was a wee bit tight. The result was the chain got thrown off.

A chain is too loose when it hits the buffers, until then, its not.

Dereck

I have also found a similar result to this. Having checked me chain with the hrlp of a friend and found the tension increases by half an inch once ridrrs is seated on bike. So now i can simply add half an inch to allow for this when setting chain on stand. An this gives me 1 1/4 to 1 1/2 inches or 32mm to 38mm
 
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