B31 Drive Chain Adjustment

[Grumps]

Hi

I have just bought a new chain for my swingarm B31. New to me bike so I thought I would treat it to a new chain as when I pull on a link at the rear of the rear sprocket the chain comes about 1/2 way up the tooth which in my mind years ago was a good way to check if the chain needed replacing.

Anyway, new chain it is. The manual says to measure the slack in the usual way with the bike under load. The bike is on it's mainstand up on the ramp with the rear wheel off the platform.

How much difference does it make to measure the slack like that or with someone sitting on the bike on the ground? Does the chain tighten up a lot between onloaded and loaded?

Thanks in advance.

[DAVE BRADY]

Hi,

Have look at the swinging arm whilst on the lift.  If it slopes down then the chain will tighten as load is applied.  If the arm is sitting level then it will go slack as load is applied.
The best thing to do is put the shock absorbers on their softest setting and get someone to sit right at the back of the bike and see how the arm sits.
The horizontal position gives the tightest position.

Dave.

[Grumps]

Thanks.
Pal of mine visiting Saturday so I'll take it off the stand but up strapped up on the lift. He's a big lad so if he sits in it I'll get a good idea.😀

[Derek996]

Hi,

Have look at the swinging arm whilst on the lift.  If it slopes down then the chain will tighten as load is applied.  If the arm is sitting level then it will go slack as load is applied.
The best thing to do is put the shock absorbers on their softest setting and get someone to sit right at the back of the bike and see how the arm sits.
The horizontal position gives the tightest position.

Dave.

Or with the bike on the centre stand, remove the shocks and put a jack below the swinging arm. Crank up the jack until the centres of the rear sprocket, the swinging arm spindle and the rear wheel spindle are all in line, then adjust the chain for ½" play. Refit the shocks and measure the play with them fitted. Note this measurement and use it for future adjustments with bike on the centre stand.

[Grumps]

Again, thanks. Manual says load the bike and allow, I think, 3/4 inch. As a quickie I'll get my pal to sit on it when new chain fitted and measure, taking into account the useful info you guys have provided on the swingarm angles.

Really appreciate the input, thanks.