I started my otherwise usually well behaved model 99 to go to work today and immediately noticed a knock from the engine. I can best describe it as like the sound of a spoon tapped against a cup, somewhat metallic and high pitched. It doesn't seem to obviously rise with revs, and on low tickover disappears, but you can get it to do it if you blip the throttle. Again, it doesn't seem to be in harmony with the engine but more intermittent.
Anyway, I didn't want to chance it so I pushed it back in the garage and borrowed the mother-in-law's death-trap Corsa to get to work.
I know this might be a variety of things, was wondering does anyone have any suggestions for a logical fault-finding approach for when (if) I make it back home this evening?
Recent history includes a new primary chain which has probably done around 500 miles by now, and conversion from twin carb to single around 300 miles ago after which it has been running like a dream. I last took it out on Wednesday evening, a ride around 10 miles or so, and this problem was not apparent then. The engine has done a little under 2000 miles since a complete rebuild which included rebore, pistons, chains, bearings etc.
Cheers in anticipation
Martin
Have a look at the primary…
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The 99 is not the quietist…
The 99 is not the quietist bike, mine has cold piston slap on minimal milage, a new slide from our Norton specialist clacks more than the worn orriginal, a loose guide can tap ,as can either of the two chains in the timing side,
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Thankyou both, this is jus…
Thankyou both, this is just the kind of levelling advice I needed. All too easy to think catastrophically when things like this happen - well it is for me anyway! I already have two other bikes awaiting surgery so hopefully with a bit of adjustment I won't need to add another to the list.
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It would be worth taking o…
It would be worth taking off the valve covers and turn the motor over to check the valve clearance has not changed,mine ran quite well with the push rod jammed half out of its cup, till the rod bent!!.
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Have a look at the primary chain - your noise could be the chain hitting the alternator mounting or the guide for the alternator wires. You would expect a little initial stretch from the primary chain, so a spot of adjustment might be the answer. Just don't have it too tight either - make sure you tension the rear chain (a well placed boot works) when you adjust the primary chaintension - or to be strictly correct, the primary chain slackness.