Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
To the best of my knowledge standard Honda valves have no "coating" although the tips may be stellite.The valve seating area on the valve you show does look to be pockmarked and as these faces are not supposed to be machines only lapped you may have a problem getting a decent seal
The valves look like the seating are burnt. It is advisable to re- face the valves and re-grind the valve seats. Check the valve guide to valve stem clearances are within spec. We find a good result de-coking valves by soaking in thinners for a day and wipe off.
Thanks for the advice! Quote from: Nurse Julie on January 09, 2022, 07:48:37 PMThe valves look like the seating are burnt. It is advisable to re- face the valves and re-grind the valve seats. Check the valve guide to valve stem clearances are within spec. We find a good result de-coking valves by soaking in thinners for a day and wipe off.@ Julie what is een-facing the valves?
FWIW except when I have had to have new valve guides on car cylinder heads I have found most valves will seat ok by just going throught the two grades of grinding paste. Coarse to remove the worst bits then fine for the final seating. It's tedious but I've always managed to get the surfaces back to where they should be. Professional engine r-ebuilders often re-face the seats as it's more cost effective but if your labour is free then its worth a shot.It's time consuming but unless you have serious pock marks on the seating face they usually clean up okay. Your fist grind with coarse paste will usually reveal if the pock marks are too deep so need re-facing.
Hope someone can teach me on this. Is it true that some valves are special and are not supposed to be lapped and if you do, you will do more harm than good? Second question: what is it precisely, that causes valves to wear?