Head-Ache!

I've taken a bit of advice from Roy at Slipstream.

Clearance on the cam lobes to the inside of the rockerbox is really tight.

I measured it in the region of around 2 thou, maybe less. He reckoned 10 thou minimum to avoid scraping oil off the lobe. So thats a bit of "nibbling" with the Dremel to do.

I don't suppose you can really see too much in these lo res pictures, but I'm on dial-up, so you'll just have to imagine that they're decent!

Below you can see where its been relieved already, but I suppose there is a bit more to take off. I think the wall is pretty thick, so its not going to do too much harm.

It does mean stripping the head though, something I initially wasn't going to do! Lazy old Duncan?

And then an initial build with an old head gasket to check piston to valve clearances. Oh well, there goes my idea of "build once"!

For info, he reckons Yamabond gasket cement on the barrel and rockerbox, nothing on the head. As for the copper washers under the head-bolts some Yam heads had 'em some didn't.
Mine is a 2KF (Yamaha XT600) head and barrel.
No Loctite anywhere, and torque to factory specs. So I'll phone again once he's had a chance to check about the copper washers. Good bloke is Roy! I think him and Martin be getting a few stupid questions before this engine is up and running....

Andy