Hi again,

I noticed the chain was very slack the other day, I have the user manual which is as clear as mud, it says I should have 2cm of play near the tensioner, where abouts?

adjut on snail cams so on the same numbers on both sides, then make sure tight enough at the chain tenson block that you can just about fit your thumb between the chain tension block and the swing arm

Thats with the bike supported eg the swing arm hanging down - your finger should fit between the chain tensioner and underside of the swinging arm

I would qualify Benwall's advice by saying that you should adjust the snail cams so that the sprockets are in line - this should be the same as having the graduations equal but seldom is due to production tolerances and, shall we say, wear and tear.

I would qualify Benwall's advice by saying that you should adjust the snail cams so that the sprockets are in line - this should be the same as having the graduations equal but seldom is due to production tolerances and, shall we say, wear and tear.

Other than actually measuring center-to-center rear axle/swingarm pivot, a quick "tell" is to look down the upper chain from the back. The chain should be absolutely straight from rear to counterhaft sprockets and any "bow" to the chain run will indicate misalignment.

Jon

The uppermost part of my tensioner is touching the swinging arm and the chain is reasonably taught below that. Should the gap be between the top of my tensioner and the swinging arm or the chain and tensioner ?

With the bike supported on a paddock stand and the wheel/swing arm hanging the gap should be between the top of your tensioner block and the underside of the swinging arm.

If you want to be really sure, next time you have the rear unit off, put the rear wheel spindle, swing arm pivot and rear sprocket centre in a line. This is where the chain is at its tightest and should just be comfortably tensioned.

Looking along the sprockets by eye is good enough on a trials bike but if you really are fussy for alignment you need a straight edge along the wheels. I could never find a good straight edge that did not weigh a lot and thus difficult to handle, to check the road bike, until I read Kevin Cameron's "Sportbike Performance Handbook" (off-putting title but a very interesting read) which came up with the obvious answer - fluorescent tubes.

Of course, given the qualitty of manufacture, having the wheels correctly aligned does not guarantee the sprockets being correctly aligned as this also requires the motor to be correctly set in the frame so a compromise is sometimes needed.

With the bike supported on a paddock stand and the wheel/swing arm hanging the gap should be between the top of your tensioner block and the underside of the swinging arm.

Correct. And pushing down on the tensioner block to reduce tension on the chain makes adjusting the axle cam a lot easier.

Jon

Finding this myself for the first time.... looks like a simple system, line it all up and bosh... still spent ages checking along the chain and across the axle.... will check again in the morning.  Definitely a footery arrangement!

What does the correct tension look like? Never run one of these before (only scramblers with idler pulley near front sprocket) and thinking I’ve set mine a bit slack...