Pulling apart my next project. RZ250 w/350 pistons

[Gavin]

If you have been following my other thread about the RZ250 you will know it's now parked up in the corner waiting on the fairings and tank to be done. So onto my next basket case.
I acquired another RZ250 F1 that has had a set of 350 barrels added. Looks like it had been run like that for a while but something went seriously wrong and I'm stripping it down. When the head came off I found one piston had metal bits inside it and as you would expect a nasty pitted surface on the piston itself.



And a comparison shot of the head showing a different operating burn.



You can see the pitted cylinder clearly.


I don't know where the bits have come from but the crank doesn't make a full circle so I suspect when I get to it, there will be something broken off or jamming it. I'll send it off to Link when it's out.

So now question time.... Do I measure the piston or pots to find the current piston size? Both pots measure 64.44 or 64.51 if I put a little pressure in the calipers. I'm guessing I have a 64.5 2nd oversize - could someone please confirm before I order the new piston kit.

Thanks
G








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[JonW]

Pull it all apart first Gavin, the cyls could be scored badly needing a rebore etc.

Looks to me like the crank seals failed, but could be anything of course. pull the cyls and the crank and lets see some pics...

[James W.]

Gav, Jon is correct, best you strip it down & carefully inspect the whole plot..

& I'd def' recommend getting those bores properly/professionally miked up for rebore sizing- before ordering the new pistons..

[BRG1200]

Don't go any more oversizes than you have to, barrels are getting fairly scarce, not that you don't know that.

[Gavin]

Thanks for the advice. I started to add up the replacement bits needed just to get it running again, and found it would exceed the value of the bike as a whole, so I decided to move it along on eBay. I did put a shout out to Forum members if anyone wanted it, in the Bikes for sale section. It's over reserve so it will still tomorrow. Can sell the spare tank for it now too.


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[BRG1200]

Good luck with the sale