Adjusting My Chain

By:KevInYorks

This is a reprint of Kevin's post on the UK KTM Forum. It is specific to another KTM dualsport bike, but the general procedure is applicable to all motorcycles with a chain final drive.

I thought I would share the theory with you..

The idea is to remove shock (easy on KTM RFS models) and block up the rear wheel until the rear wheel spindle, swingarm spindle and gearbox output shaft are all in line.

This is the tightest the chain will ever get to during it's travel.

Then adjust the chain so it is has barely any free play.

Then lower the wheel and replace the shock.

Then check the chain play with the rear wheel off the ground.... this is the amount of play you need to adjust your chain to in the future...... so long as you still have the same size sprockets (see my comment at the bottom of page)


1st photo shows rear wheel chocked up by 260mm of timber to bring the three shafts into line.

The string line can just be seen

Second photo shows a close up of the string line. Chain has only a small amount of play.

Third photo shows the chain tension when the shock is back in and the wheel is off the ground. Three links of the chain can be pressed onto the top of the swingarm.

It has to be this loose.

If it were tighter the chain would be even tighter than a guitar string when the suspension is compressed. This would cause damage to the gearbox output shaft bearing, chain and rear wheel bearings.

BTW the bike has 14:40 gearing. When I did the same procedure with 13:50 off road gearing the chain could not be pressed closer than 3mm away from the top of the swingarm. Its this dramatic difference caused by sprocket sizes that can catch out the unwary.

 

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