Le singe
Guest
My 1100GS engine developed an intermittent top-end 'clanking' noise this weekend. It happens around 2K rpm then clears. It also does the same on start-up but clears after a few seconds of running.
I've done a search on the site and found others who've suffered the same problem, the only difference being that mine has started on the RH cylinder.
I've stripped the top-end and found nothing that is worn or damaged, the camchain tensioners are perfect,no evidence of scoring on the pistons or their bores. The spring length has been checked against new and everything appears OK.
I haven't been able to measure the spring rate against new,but usually weakening is coupled with a reduction in length, so I'm assuming, (hopefully rightly),that it's still in tolerance.
I re-assembled the tensioner and re-fitted it, turned to engine to TDC overlap,backed it off just enough to put slack in the camchain,then turned the engine in the normal direction of rotation. The exhaust valves would obviously stay static until the slack in the chain was removed,then they would slam closed more quickly than if they were being controlled properly.
This resulted in a noise identical to that being heard when the engine was running.
The problem suggests that the tensioner has become too weak to control normal 'load-unload' working of the chain or the camchain has stretched enough to take the tensioner out of it's designed range of chain control.
I'm going to fit a rod,with a measure of free-play, to the tensioner to limit it's rebound range,as someone has fitted before. I cannot see a problem with this remedy as most engines use a tensioner with incorporates a type of ratchet control as well as spring tension.
I don't know whether others who've replaced the tensioner assembly with new have removed the problem totally or whether it has re-occurred quite soon.
My engine has covered just 77K km so is not high mileage.
I should add that the problem has only occurred after I fitted the 'S' spec camshafts although all the tensioners,etc,are the same for all the motors of this era.
I've done a search on the site and found others who've suffered the same problem, the only difference being that mine has started on the RH cylinder.
I've stripped the top-end and found nothing that is worn or damaged, the camchain tensioners are perfect,no evidence of scoring on the pistons or their bores. The spring length has been checked against new and everything appears OK.
I haven't been able to measure the spring rate against new,but usually weakening is coupled with a reduction in length, so I'm assuming, (hopefully rightly),that it's still in tolerance.
I re-assembled the tensioner and re-fitted it, turned to engine to TDC overlap,backed it off just enough to put slack in the camchain,then turned the engine in the normal direction of rotation. The exhaust valves would obviously stay static until the slack in the chain was removed,then they would slam closed more quickly than if they were being controlled properly.
This resulted in a noise identical to that being heard when the engine was running.
The problem suggests that the tensioner has become too weak to control normal 'load-unload' working of the chain or the camchain has stretched enough to take the tensioner out of it's designed range of chain control.
I'm going to fit a rod,with a measure of free-play, to the tensioner to limit it's rebound range,as someone has fitted before. I cannot see a problem with this remedy as most engines use a tensioner with incorporates a type of ratchet control as well as spring tension.
I don't know whether others who've replaced the tensioner assembly with new have removed the problem totally or whether it has re-occurred quite soon.
My engine has covered just 77K km so is not high mileage.
I should add that the problem has only occurred after I fitted the 'S' spec camshafts although all the tensioners,etc,are the same for all the motors of this era.
