thall1 Posted September 13, 2015 Report Share Posted September 13, 2015 Hi guys, I have a 4 rt which 'coughs' every now and again. It has been suggested that maybe either the fly wheel has sheared the drive key and slipped a little or maybe the chain has jumped on the sprockets. I have lifted the valve cover off and with the fly wheel on the 'T' mark the cam timing marks are not in line with the top face of the head casting. They are approximately 2mm high at the front and low at the rear on the sprocket. However this is with the chain still loaded with the cam tensioner which I guess would/ could rotate the cam backwards slightly?. Should I expect to see the cam sprocket marks in line with the top face of the head with the chain loaded or not? Quote Link to comment Share on other sites More sharing options...
jrsunt Posted September 13, 2015 Report Share Posted September 13, 2015 I've not heard of sheering the woodruff key or jumping a tooth before, but there's always a first. What age is the bike and do you have the workshop manual to hand? There are a few marks on the flywheel, do any of those allow for alignment? Quote Link to comment Share on other sites More sharing options...
thall1 Posted September 13, 2015 Author Report Share Posted September 13, 2015 Hi, I do know of a bike locally with a sheared key that was half way sheared. Had the same symptoms as ours but the miss-alignment was approx 20mm on tdc mark. The manual only describes the alignment on rebuild not for checking. There was a piston this forum with a new bike that had jumped a tooth..... Quote Link to comment Share on other sites More sharing options...
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