Mag chain madness

My mag chain goes from slack ( 1/2") to really tight as I turn the engine. I've fitted a new inlet cam bush so would guess that that end of the chain is running true so the only other culprit must be a wonky armature shaft? Or dodgy sprockets? It's a new chain. Any views? Cheers, George

George, either something has gone ecentric or you got some solid links in the chain. Rotate the relative shafts individually and observe any ecentricity relative to a set point of your choosing.

Ensure your chain is 360 degree flexible, then test the link if it has one; set it in the chain and run it over your fingers in both directions to ensure complete movement of the chain and the joint.

Failing that, check your mag platform hasn't cracked......

Jon

If the key on the drive sprocket is too tall or not fitted correctly, this will make the sprocket run out of true.

Colin

its gone a bit grey

Is this new dark colouring NOC's attempt to emulate the "Access Norton"s Web Site?

People often do not compensate with the appropriate back pressure rotation when measuring chain tension. This is profound with the high loading of the camshaft timing chain but still applies to the weaker rotational loading that a magneto creates, Trick is to rotate the DRIVEN sprocket/gear TOWARDS the turning force direction(to oppose it)that the chain is creating at at any time...then measure the slack....Les