Familiar symptoms to anyone?

[benny hedges]

you are one sick crouton mr foz, that's not a job i'd look forward to doing lol!

[tony.mon]

Firstly, if it jumped a tooth at the lower end you would have BOTH cams one or more teeth out.
Whenever I've stripped and checked an engine it's always just been one, so I don't think this happens normally.

But it's possible.

Next, although the chain stretches (wears, actually) a bit it's not going to be enough to allow the sprocket to move forward a whole tooth, so you'll still be able to get the marks lined up near enough.
But I think you're being too perfectionist; the marks won't line up EXACTLY, you just settle on the nearest tooth to dead level.

If you want to time them more precisely, you'll need to slot the sprocket mounting holes and adjust each sprocket with a dial gauge on the cam lobe to set the middle position.

Unless you're racing I wouldn't bother. These engines are very under-stressed, and although they're capable of putting out quite a bit more they're under-tuned as standard.
SO as long as you get the cams as near as you can to a level timing mark with the tension on the tensioner side then that'll do.
To get the tension on, just rotate the camshaft sprocket against the normal run of the engine, I can't say clockwise or anticlockwise as you look from different sides of the engine depending on whether you're working on the front or rear cyl.

You'll be fine with them a little bit out, you have to be more than one tooth out for the piston to touch the valve.

Just remember to turn the engine over several times by hand (in the correct direction) feeling for sudden stops. If there aren't any, fire it up and ride the thing.

[benny hedges]

front exhaust cam was one tooth out on mine when i stripped it to fit apes.... it did run ok but popped a bit on over-run.

[Fozzie]

Thanks for all the advice. As the bike has done 50k and I can't be sure they've ever been changed I'll change them anyway. You are probably right I am being a perfectionist. Still I got a cam chain and the new one makes the marks on the cams line up almost perfectly. Seems to run a bit smoother too although that might be down to the fact I've been using a 21 year old cbr600 for the last week. The only issue I had was with the tensioner. I set it for 5mm play up and 5mm down on the chain but when I fired it up, warmed it up and then revved it a little the front head sounded rattley. So I tightened it by hand a bit, the rattle went but still sounds a bit noisy. I know my hearing is pretty crap so wondering if some auto CCts with the stopper mod might be better for me or am I being a nob about things being perfect again?

[benny hedges]

did you check the valve clearances while the top was off????
at 50k it's probably well ovedue!

[jonnyjameswalker]

I have got the exact same problem with mine Fozzie, seems to misfire when at low speed, and my front cams are both 5mm off from the cylinder head, but line up when no tension, rear chain and markings are perfect, you say your new chain solved the problem? Im not keen on having to change the cam chain, the bike has only done 8000 miles :-/

[benny hedges]

I have got the exact same problem with mine Fozzie, seems to misfire when at low speed, and my front cams are both 5mm off from the cylinder head, but line up when no tension, rear chain and markings are perfect, you say your new chain solved the problem? Im not keen on having to change the cam chain, the bike has only done 8000 miles :-/

not all misfire problems are related to cam timing.
and it wont need need new camchains at 8k.
when checking the marks you need to pull the chain back toward the tensioner side so the non-tensioner side is taut.

have you had a k&n filter fitted or dynojet kit that wasnt set up on a dyno?
does it still have original spark plugs in?
a fuel related misfire will feel like pulling the choke out when the engine is hot.
an ignition related misfire will feel like flicking the kill switch on& off