1977 Honda CB750F update 6

Well, lots going on in today’s post- We are lapping in the valves and reassembling the head. As it turned out, 2 of the exhaust valve seats were oval from the valve guides being so worn. I found this out after getting the valves refaced to eliminate the pitting and then trying to lap them in with valve grinding compound. When you lap the valves, the grinding compound will leave a dull ring where the valve and seat are touching. In the picture below, you can see the nice dull gray ring on the seats. If you do not see the ring going all the way around, you know that the valve is not seating properly. Here are pictures of the valves before and after cutting. It’s no wonder the compression was so low and the bike ran so poorly!

lapped valve seats

lapped valve seats

pitted valve

pitted valve

refaced valve

refaced valve

lapped valve

lapped valve

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!

You must be logged in to post a comment.