It looks like these barrels have been modded like RS250 barrels with the insert grooves machined in.

Does any body know the spec on the RS250 o-rings, dia, thickness, material etc.

It would make sense that if you are going to do a mod like this, that you would do it so you can use a standard consumable part thats easily available.

So... I have three choices; put the heads back on with just the OE gasket, find a supplier for the O-rings and fit with O-rings only, or finally, O-rings plus the gaskets.

I suppose there is a fourth option, to source some standard barrels; but I think cost and availability will rule this out on the budget I have set on this bike.

Without a bit more research I am not sure what to do for the best at the moment, and I don't even want to think about the consequences of getting this wrong.
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Russ

MC21SP