Noisy or not noisy?

I've never had a 99 and cannot advise on settings, however if you believe it is running hot you need do some checking right off!

there are several items that can cause hot running engines, one of the worst can be an air leak somewhere at the intake manifold connections. that can destroy your engine rather quickly.

the wrong carb settings and non standard exhaust systems can also create a lean burning fuel mixture causing hot temps.

I should double check all before riding further, if one suspects something is wrong it is best to trust ones instinct, even after 40 years!

Of course if it hasnt changed after 500 miles itmay be your memory, if a noticeable change has just occured then it could be the carb loosening up causingan airleak...

Dear All,

My 1960 99 engine has just been professionnally & fully rebuilt from top to bottom with parts provided by RGM (Eg : GPM pistons).

I'm still running it in (about 500 miles covered now).

I think that the main set-up values are OK (valve clearance, timing = 31? BTDC full advance; NGK 7 ES plugs ; carb-setting looks OK).

butthe engineseems to be really hot after a fewmiles(as far as I remember from my previous Dommie 40 years ago!) and is really noisy (noise coming from the pushrod / rocker / valve train. Everything OK for the bottom end. Appearently no piston rattle).

Thks for letting me know your thoughts about that.

PS : Anyway, it does not prevent me from enjoying her on the sunny french roads!

Have a great riding week-end

Having, over many years, been asked to sort out quite a few Norton Twin cylinder engines that have decided to try and cook themselves my first port of call would be to recheck the camshaft timing. I have come across many motors where the either the half-pinion has been one tooth out or the camshaft chain has jumped a tooth. The engine have generally started and run but in most cases quickly overheated and been very noisy.

A rough but reasonable check can be made by clamping a timing disc to the crankshaft and then watching the inlet valve open and close as the engine is turned.

This valve should show signs of movement at around 50* BTDC depending on valve clearances and which camshaft is sitting in the engine.Plus setting the valve clearance to 13 thou.It should then close at roughly 77* ATDC. These are the timings fora QR Camshaft , which would be correct for the model and year of your machine. An SS camshaft should give similar numbers but a pre 1959 camsfat will be quite different.

Any numbers 15* different from the above would suggest the Intermediate gear is 1 tooth out and a 40* difference would suggest the cam chain is 1 tooth short or long.

Also agree with the other posted comments that air leaks and poor ignition timing cause similar problems. As a rule however, cracking open the throttle would give the game away if eitherthe mixture or timing is badly wrong. iepoor accelerationbut lots of noise.

What are you plug colours?

Is your advance/retard doing a proper job?