Lumpdog -
it's great to hear there will be someone else with the full Kibblewhite valve train. It sounds like you'll have the stainless valves and the Kibble springs that go along with them. Once you have everything back together, I'm looking forward to hearing what you think of the setup. I'm enjoying it, though it's been way too cold out to ride here, the past 3-4 weeks now.
I'll try to respond to your questions, from my experience with the Kibbles so far. Again, I think you're making a solid move.
What other parts are worth replacing at the same time , head gasket is an obvious one as are vs oil seals etc , what about the valve seats ??
Yes, the head gasket is one. Also if you choose to (depending on your budget and also on your judgement of whether or not it's time for it) I also took the opportunity to replace the piston and rings. Mainly I chose to do this because I'd never replaced a piston in a motor before and wanted to give that a shot. Other than some discoloring and a little build-up on the top of the stock piston, there wasn't much visably wrong with it. A new set of rings may have been sufficient, but the book does call for a piston replacement (err, after 15 hours of riding, which may be a little on the overkill side... afterall it's not a 2-stroke)...
Also need a head pipe gasket, as this is a crush type brass or copper deal.
If you do replace the piston, you'll need the piston, rings, and connecting rod (usually come with the replacement piston), and the jug gasket (goes between the jug (cylinder) and the base of the engine.
The other seals can be reused if they're in good shape (large cap seal which goes around the valve cover, and the spark plug gasket).
I think my kibblewhite kit came with: valves, springs, and stem seals. I had the local engine shop install all of these. The valve guides weren't in need of replacing so we chose to re-use the stock ones (which stay in the head, unless you go out of your way to remove them). They are what keep the valves traveling at a true 90° angle to their relative angle in the head. (In other words, if or when they wear, the valve would be able to have woller or play in a circular way during its travel... NOT good for the valve seats, which are actually a part of the head itself and not replaceable (I'm pretty sure).
The valve seats may need to be touched up by the engine shop, if the stock valves have worn and begun to change the proper angle of the seats. It needs to be perfect milling to create a no-leak seal between the seat and the valve, so this is best left to the shop.
Do the valves need lapping in ? Will doing so ruin any exterior coatings on the valves ?
Will lapping in hamper performance ?
What size shims will be required to get the new valves into tolerance ?
Lapping from what I understand is to help conform the valve and seat to the new seat shape (after they cut the seats). Should be ok since I don't believe stainless valves have the special coating the Ti's do.
Shimming will be trial and error, but it can be done on a workbench as someone here pointed out a few months back. Much easier on a bench. Then once you get your proper shims picked, go for on-the-bike install.
Break in - go easy the first ride after assembly. I would use fresh oil after reassembly, and change the oil and filter after the break-in ride. Then check your clearances. If they are still in speck, it's open season (ride it normal)! Then resume valve clearance checks as a normal maintenance routine. They shouldn't move any more, though.
Good luck, let us know how you make out.
Also interested to hear how the ride feels after you're up and going again. If you need more advice, give 124, Ken or ~ a ping - they are encyclopedias when it comes to this stuff. Some pretty expert knowledge going on there.
-matt
Cheers for that , i only mention lapping in because when ive done car engines before its normally not something that you do too much when building a performance engine .
