Valve Job: Lapping-in Valves

I'm doing a top-end job on a 1995 Kaw Vulcan 1500A V-twin. The valves
have about 100k miles. A leak-down test showed 10% loss last year and
%15% loss this year in both jugs, so it looked like it wa's time to
check and fix thngs.

Looking at the valves and seats, I saw pitting on all 8 sets. The
exhaust valves seem to have experienced the worst wear. I've miked the
valve stems and did a "wobble" test on the valve guides and both were
in spec on all valves (much to my surprise).

I've miked the valves seats and they are a little wider than spec by
about 0.25 mm on all four exhaust valves after hand-lapping the valves.
My question is, will the bike run OK with these slighty wider seats,
or do I have to gind the seats to make them narrower?

TIA for tips and suggestions,

Manjo

 

The racing guys like to run really narrow valve seats to increase the
point pressure of the valve seal. Narrower seats are easier to burn
than wider seats because they can't get rid of the heat. I would just
call it an endurance valve job and reassemble the motor.

 

yes its not to good to have a wide seat as a narrower one is less likly to
get burned or filled with carbon deposits i would suggest to get the seats
cut your local machine shop should be able to do this as well as the dealer.
also put rings in as with the added valve pressure will make more leakage
past your rings and cause it to suddenly burn oil rule of thumb dont do one
without the other.

 

Whenever we used to work on an engine, we figured it was a good idea to lap
the valves as long as the head was off & on the bench anyway. How much they
got lapped depended on their condition -- even just smoothing out that
pitting would be a good thing.

 

oskar, alan, Ron, and Nomen,

Thanks for the replies, tips, and suggestions.

I have all the valves lapped in and will go for "endurance". I also
have new valve oil seals for all the valves.

One thing has developed that looks strange to me. On both rear jug
exhaust seats and corresponding valves, concentric circles/ridges have
developed where the valve meets the seat. Of the eight(8) seats, these
are the only two where these circles/rings have developed (these are
also the two seats that had the most pitting, needing the most work).

I'm prone to just reassembling the headed and look for leaks. I'm
concerned that I've done something wrong. Should I do more lapping to
get the rings out??

Anyone seen rings like this before? If so, what was done to get rid of
them, or can they be lived with?? Your suggestions are appreciated.

TIA for your help,

Manjo