93 yamaha xj600 (seca II) cam chain tensioner relacement.

Failing electronic ignition or a RPM limit has been reached.

ON THE BACK OF THE HEAD THERE IS A TENSIONER ADJUSTER TAKE THE SCREW OUT OF IT AND PLACE A SMALL SCREWDRIVER IN THE HOLE HOLD IT IN WHILE RUNING AT IDLE IF THE NOISE STOPS ITS THE TENTIONER...HOPE THIS HELPS..

On the back of the cylinders is the cam chain tensioner. Find the timing marks for the motor and set the motor to top dead center (TDC) on the compression stroke for the #1 cylinder. Piston up, both valves loose (not pressing on valves). Now loosen the bolt on top off the tensioner and tighten it back up. You have just adjusted your cam chain tensioner.

The XJ600 has a self adjusting timing chain tensioner, although it's robust enough, like the previous post say's they can stick. To remove the adjuster look at the back of the engine on the cylinder head, the tensioner is there, two bolts hold it on one above and one below. to remove the tensioner there is a spring tensioner in the centre of the unit, undo this with care it hold the pressure spring in place on the plunger. Now remove the retaining bolts very carfully, equal turns on each bolts (do not take one out fully, leaving the other in place fully tight).
Once off the engine DO NOT ROTATE the engine. The tensioner should move freely, although there is a rachet system that locks it out, if it moves out freely then it's fine. To re-fit the tensioner release the tensioner make sure it's adjusted fully inwards and use a fresh gasket. The tensioner only firs one way, if it won't fit don't force it and it can be broken easily. Tighten both retaining bolts evenly and per the removal. Re-fit the tensioning spring and retaining bolt (do not over tighten) the plunger is self adjusting from here.