QuestionI put the valves in tonight. I put mineral spirits in the top and there is oozing slightly especially the exhaust. I checked the valves with blue coloring and the ring looked nice to me on both the valves. Should I lap them with fine compound or leave well enough alond? Thanks
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Do you have to have a battery to start the bike or is that mainly for the lights,horn etc? The valves that were on the head look good but I read where you should not use lapping compound because of the surface metal on them. And then some say lap. I don't know if they are honda valves. Is there a way to tell? I tried lapping before and can't get perfect results with leaking. Shirley
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Aloha, Shirley... The ignition system is magneto, so no battery required to run the motor. Battery is a reservoir for the charging system to light the lights and horn. If you run the motor w/o a battery, the charging system will go to full output and fry the light bulbs. Either disconnect EVERYTHING related to the charging system and electrical system, other than the ignition or put a fully charged battery in place.
You can lightly lap in Honda valves. A proper seat will show up as a thin ring in the middle of the valve head contact area. If the seat in the head is rounded over, then the flat valve face will not seat properly and thus not able to seal at the interface correctly and transfer heat as it should.
If that is the case, then the seats need to be ground properly, so that the valves can seal correctly and the seating area is in the middle of the valve face.
Be aware that if the valve guide clearances are excessive, then you can't get the valves to seat properly.
Bill Silver
AnswerPut a drop of oil on the valve stems, with everything else clean and dry, then reassemble the valves and springs. Check again. If there is any seepage, then lap them in with fine compound. It isn't clear to me if you have checked them assembled or not. The contact ring should be in the center of the edge of the valve head.
Try wiggling the valve in the guide with the valve off of the seat a 1/2 inch or so. If the guide/valve stem clearances are loose, it will be hard to seal that valve correctly. Guides don't usually wear a lot unless the engine was run without an air cleaner. If there is looseness, you will have to replace the guide, ream to size and recheck the valve seating again.
I usually check the valve sealing by pouring thinner or other light fluids into each port, one at a time (assembled with springs) and watch for any signs of leakage.
Bill Silver
