Dommi 88 500cc Head Gasket spigotted barrels .

I use a solid copper one on 88SS.  No issues.  Been there a long time.  Annealed each time it's been disturbed.  Probably from RGM.

I once tried a copper gasket but got oil leaks around the pushrod tunnels.  For years I have used the rather tacky ones (can't remember what they are called) but with a PROCEDURE.  That's because the idea of re-torquing after 100 miles did not work. The gasket blew at 80. so my procedure is to re-torque at 50 or 60 miles, and again at 150 and 500 miles. If there is much "give" at 500, I may go as far as re-torquing at 1000.  A hassle as you also need to check the tappets as the head squidges down.  But I get a bullet proof joint.  I have put about 130000 miles on my dommi 88 in 26 years of ownership.  Warning: the edges of the very thin copper, top and bottom of the gasket, can really slice your fingers as you struggle fitting the cylinder head.  John Powell

Sorry for late reply.  Yes, the ones you describe. Have not looked at the web site for a while

While cleaning the alloy cylinder head of my Domi I discovered different exhaust valves were fitted. LH cylinder has 32 mm (1.26") the RH has 33.3 mm (1.312"). I think 33.3 mm is correct. I always thought the LH cylinder was running too rich with a black plug and now I found much carbon in the combustion chamber and exhaust port. I also suspect that extra vibration was caused by different power delivery left and right and both crank shaft and bearings have had a hard time (resulting in a complete engine overhall). So are my assumptions right and is it wiser to fit a bigger valve?