Hello and my 1st post after my 250/1 sezied.

[DAVIDGUEST123]

Right then, I’ve finally got the barrel back from the engineering chap( top bloke but takes his time) before chucking it all back together is there anything I should pay particular attention to? Also what should the piston ring gap be? Any help would as usual be gratefully received.
Thanks Dave

[Puffs]

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[DAVIDGUEST123]

Thanks for that Puffs. I keep you informed as to how I get on. One last thing, is there any reason I can’t pop the piston into the barrel before sliding it down onto the con rod?
Thank again Dave

[Puffs]

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[DAVIDGUEST123]

Well... it’s back together and running.

Starts well, pulls fine, no horrible bottom end noises, but it sounds like either the small end is worn ( yes some people just don’t take advice. Low funds made me deaf) or piston slap. I’m going to run it for little while as is, but the noise is quite pronounced.

I’m a bit loathed to strip it again as I did examine all the bearings for play and in my humble opinion they seemed fine.

So I a little lost as per what to do?

Thanks Dave

[Puffs]

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[DAVIDGUEST123]

Bad news it is. All back together with new long pin needle roller bearings and although the engine does sound very slightly better it still has a rattle. So it's engine out time.
There didn't seem to be any wear to the bearing surface of the con rod at the top end although I could detect a slight left/right movement at the lower end. I think this maybe the issue ..so out it comes.

I think my next move may be to have the engine stripped by someone with a liitle more knowledge than myself...Any recommendations?

Many thanks Dave

[Puffs]

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[Puffs]

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[DAVIDGUEST123]

Thanks Puffs for the infomation. The story continues, I decided that as I'm going to keep the bike for some considerable time I'd get it fully rebuilt by a professional. So I've taken it down to Martin Burwins who went though it with a fine tooth combe. The Big end had statred to remove its surface very much like the photos of your small end pin. The clutch had started to spin aon the shaft and there was quite a bit of wear to the various known gearbox slector parts. So i'm now happy that the engone is fine.
The only issue I have is that there is still quite a bit of the noise from the top end which Martin did tell me that the rebore is a little on the large side with a piston clearance of 3 thou. The bike run fine but is a little difficult to start. The question now is do I rebore again or will it get better with use?
Many thanks

[Puffs]

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