roller bearing vs. swinging arm bushes?

[Phil]

By the way ... I agree with you 100% on tuning these engines - it's just a bit of fun and it's just as well to fit a Wiseco 836cc kit as trying to get OEM pistons - same story with valves etc. I have a CB900 Hornet which is way quicker. Today I took two heads (from an F2 and a K6) to a racing car engine preparation place and the guy there was intrigued when I said the F2 heads were not used because of the valve angles. he said it was a much better design but on both engines the exhaust valves were far too big and this would cost BHP. The correct size for the exhaust valve is 26mm. He is flow testing them for me and will report the BHP potential soon. The plan is to have a mildly tuned engine in a close CR replica and a proper racing engine in the other bike. This guy incidentally, did the work on the Moto Guzzi MGSO1 for the factory and was grinding some racing camshafts for Maserati when I called by! Pretty cool place and only a couple of miles away.  Phil

[Voxonda]

Hey Phil, everything on my bikes is 'homemade' so to speak. I know of the problems with Ti, but have no experience with it myself. Give me a pm about the prizes etc.
What I meant in my comments about the head of the F2, is that in day to day practice it's crap, mainly because of it's habbit to eat valve guides ie oil consumption. In theory it's a better design, it just doesn't show it. You're engine man may have a point about the exhaust valves, to big means loss of (air-)speed. Am very interested in the outcome of his investication. It really good to have someone like that 'around the corner'.

Rob