I am familiar with valve grinding; have done it numerous times on my Triumphs. I tried to obtain a rather narrow .5 to .7 mm ring on the valve seats, but on my NOS barrel I can't get rid of the faint circular machining marks. And yes, the valve is NOS, I use the correct first coarse and then fine grits, with an oscillating movement
Question: do I have to get rid of those machining marks

email (option): viaconsu [at] planet'dot'nl

Makes me wonder if the new barrel seats are roughed in by machine tool, that then requires final finishing with a conical grind stone. The better the seat you get now, the less likelyhood of a valve burning in the future. Ron

email (option): ronpier@talk21.com

Sounds like it needs a pass with a valve seat cutter to get correct valve seat width and remove marks. Grinding in is only to perfect the valve to seat seal.

Hi Hans..If you can find someone with a Serdi head machine and valve refacer that can give both a very light 'tickle', you don't even need to lap them after they are done..Ian

email (option): ian@wright52.plus.com