So I put in new valves and guides, and am noticing a sliver of light between the valve seat. Ive been reading tons of stuff but cant find a definitive answer. Its a very small gap, can i just lap the new valves, or should i be cutting new seats? Thanks.
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Punkskalar
Hugh's HandBuilt
Yep, new guides are gonna require new valve seats to be cut...
PetesPonies
XS650 Addict
When you can see light, you are past what lapping can do for you. You need the seat concentric to the guide hole. They must be ground.
No, you must have the seats re-cut and the new valves need refacing also. Once you remove the guides,everything gets out of alignment.
ok thanks guys. So as far as getting the kit from Mikes and doing it myself - anyone have any experience with that? How hard is it? Im mechanical and competent with my tools, but not much "machining" experience. Also i have five xs's , so learning to do this wouldn't be a bad idea. The kit would pay for itself, im in the sticks and to get the heads to a competent shop is a real chore. cant be that hard right.....right?
Save your money and just take the head to a local machine shop to re-cut the seats and valves,that simple
TwoJugs
Excess XS
DO NOT buy mikes valve cutting kit. It is a joke! I got sucked into thinking it would be a great deal. It does not touch the seats. A real kit costs $800 +++ I guess I got my $140 worth. The wood box is nice. If you want to give it a try buy mine. I will give you a better price and it is pre tested to not work. So far the most expensive useless item I got from them to date.
PetesPonies
XS650 Addict
Absolutely take the head to a shop. Many engine builders farm out this operation. Its so easy to do when you are set up for it. I bought a valve grinding machine for me to use in my shop. I enjoy trying these things, so I understand your interest. But you will be happier to have it right and do all the assembly yourself. This isn't a place to learn on the fly.
angus67
Welder's penetrate deeper!!
just take it in. I rebiult my motor, it had a busted wrist pin, so I had to get new valves,.
When I took it to the shop, I asked them to check the guides with the new valves, and they were fine, they cut new seats, and did just the slightest deck shave, and cleaned it all up for 40 bucks.
I went to that particular shop cuz I had heard thru a few older gents that the machinist there used to love 650's. I wonder if I gave him a little thrill draggin that crusty, beat up 650 head in there, instead of stupid brake drums off some dumb POS car.
When I picked it up, I asked if I needed to lap the valves in and he said no. ready to go. Maybe he did it himself for old time's sake. Who knows?
Threw it all back together with a 1.5 over piston kit from mikes. 155 compression on both sides and even though it has no brakes still, I ride it up/down my 100yd drive all the time.
Ifigure its now a 680? with those bigger pistons? not sure. someone said that here once.
beer. rambling.
yeah, let the pros do it, then you know is right..
When I took it to the shop, I asked them to check the guides with the new valves, and they were fine, they cut new seats, and did just the slightest deck shave, and cleaned it all up for 40 bucks.
I went to that particular shop cuz I had heard thru a few older gents that the machinist there used to love 650's. I wonder if I gave him a little thrill draggin that crusty, beat up 650 head in there, instead of stupid brake drums off some dumb POS car.
When I picked it up, I asked if I needed to lap the valves in and he said no. ready to go. Maybe he did it himself for old time's sake. Who knows?
Threw it all back together with a 1.5 over piston kit from mikes. 155 compression on both sides and even though it has no brakes still, I ride it up/down my 100yd drive all the time.
Ifigure its now a 680? with those bigger pistons? not sure. someone said that here once.
beer. rambling.
yeah, let the pros do it, then you know is right..
PetesPonies
XS650 Addict
Actually lapping valves after a proper valve seating is not needed.
angus67
Welder's penetrate deeper!!
it was my first time, so I figured I should ask, instead of pretending to know.
