Top end rattle/ tapping noise

[cmm7]

I have jsut bought a CRM250, first 2 stroke I have owned since a kid many years ago. Great fun bike however I have a slight concern reference an engine noise. The engine was apparently rebuilt approx 1000 kms ago and bottom end + gearbox seems quite, sounds mechanically quite when reved but fairly loud tapping sound at tickover..sounds like noisy tappet on 4 stroke (obviously not applicable on 2 stroke but best way I can describe the noise).. As the revs increase the noise seems to disappear...could be small end but I thought would get worse under load not better. I do not really want to strip top end out unless really neccessary but a liitle concerned..Any ideas please.

[keithl8187]

Same here. Just bought 1991 MK2, noticed similar sound at tickover which seemed to become less frequent as it warmed up. Sounds a bit like pre-ignition, runs quiet with a few revs on though. Haven't had chance to give it a run out yet.
How's yours, is it still making the noise or did you find out any more about it. The guys at Leisure Trail are the experts apparently.

[rhysdad]

My MK1 was the same when i got it. Lots of similar threads too re this very condition. Mine (touchwood) has been fine for the last six months, run on fully synthetic oil and is still sweet as a nut. I've put it down to 2 stroke piston slap and general 2 stroke temperament. Doesn't mean that you could put your engine noises down to that purely but it does seem to be a feature of these lovely bikes!!!

[knackeredMk1]

As RD says CRMs do tap. Some more some less. Be concerned if the noise changes to be at all revs and particularly if under load.

[cmm7]

Thanks Guys..I have removed exhaust and reached in exhaust port...no up & down play at piston so would think big and small ends ok..slide sideways rotational movement but suspect normal..however powervalve has play in it and can be rattled about...hopefully this is what causes noise and nothing to worry about..