Just rebuilt a 1959 99. I didn't split the crankcase because I was told that the bottom end had been done.
Fitted new Norvil barrel and pistons, new carb, refurbished magneto, refurbished head and new pipes and silencers. When I first started it (2nd kick)it ticked over beautifully although the exhaust note sounded very blatty and after an initial run of 20 miles it was clearly running very flat. So checked ignition timing again and auto advance and valve clearances. I put down the poor performance to a problem with the silencers, so bought another pair but still the same problem.
I am now thinking the cam may be a worn out one, so I intend to change the cam. Can anyone advise if this can be done without splitting the crankcase.
Simon - the quick answer i…
Because the dommys still h…
Because the dommys still have an oil trough they give the cams and followers a much easier time, if in good condition I would lightly stone the followers to give a new surface to the new cam and use the installation cam oil and avoid letting the motor tick over at start up. Never had a problem with cams or followers.
Thanks for all the advice.…
Thanks for all the advice. I will double check the valve chain and the cam lift before I go for the complete crankcase split.
I was wondering if you are one tooth out on the timing chain. If there is one extra tooth length on the top run the the valve timing will be retarded.
I would have imagined that a worn cam would result in a softer quieter exhaust tone.
You can check with a dial gauge directly of the push rod ends to see what the valve lift is, an easy job, not like checking valve timing which is not. If you look on the "Atlantic Green" Norton web site it will list all the valve lift specs.
Total engine strip required to change camshaft!
Check cam followers first IF after finding valve lift shortage, as they might have worn hollow....although with a new barrel these are likely to be new also.
Les