valve lapping

It seems not matter how much I lap them I do a water test and little leaks I have course and fine compound and they all sound set noise wise is that normal or should they be like super super tight...input would be great also water stay in the head chamber not like It drains like super quick

koloj wrote: It seems not matter how much I lap them I do a water test and little leaks I have course and fine compound and they all sound set noise wise is that normal or should they be like super super tight...input would be great also water stay in the head chamber not like It drains like super quick

If this means extended sessions with valve grinding compound, that isn't the proper way to achieve acceptable valve seating, and probably did more damage than good.

Good Fortune!

That didn't answer my question how tight are they suppose to be my manual says enough were no leaking...I basically checked today and wasn't no leaking....funny thing is I have another bike got for parts that was running perfect just had messed up transfer and valves leaked with water in the ports

Did you use prussian blue to check a perfect valve seat?

If you are lapping them by hand they can take awhile to set and yes a perfect seal is wanted. If he is getting leaks with water then prussian blue isn't going to tell him anything he does not already know.

As you lap the valve, you should see a margin form in the middle of the 45.
At first it will appear thin and inconsistent. With some more lapping and checking,
it will widen until it turns into a distinct band consistant all the way around. A thin margin
on one side and wide the other is a valve seat needing cut. If the valve doesn't seal after
much lapping it will develop a receiver groove and need to be cut. At the point of perfect
margin forming you can test ithe seal by inserting the valve., filling the chamber with water,
hold down the valve and shoot air into the intake, You should see tiny bubbles and few, if
the margin was close. A little more lapping and the valve should not leak ANY bubbles.
A very slight amount removed from the valve or seat makes quick work of lapping in
quickly and completely. Valve clearance doesn't tend to change ounce its shimmed ,
after lapping. If your using fine it can take a while to cut in, I use a coarser grit and it
can take a while as well, If the valve has nitride surface it would take all day with fine grit.
When the valve and seat are cut generally nice to excellent, the valve lap and seal is
quick, NO more dreaded bubbles.

Per FSM:



Where an otherwise serviceable valve isn't properly seating, cutting is often a necessary prerequisite to restore the mating surfaces, which is followed by judicious lapping -- not extended prolonged lapping -- to perfect the sealing.

Good Fortune!

If you have access to an air compressor take the assembled head and sit it on the bench with exhaust ports pointing up.
Fill the exhaust ports full of solvent if you have it,if not I suppose water will work.
Take your air hose with a blower and blow air around edge of valve face where it meets valve seat,watch for bubbles in port as you check each valve.
If you don't see any bubbles your good,flip head over and repeat on the intakes.
Make sure to measure your valve springs while its apart,the way the 650s get wound up id definitely check the springs.
As far as lapping valves I only suggest it as a finish after a valve job,30 years ago when these motors were reasonably new it wasn't a big deal.
But if you try and straighten up a really bad valve by lapping it Id be willing to bet youll just end up screwing up a valve seat.

Check for bubbles with springs on or off

Springs on,head assembled.

Some will not agree with this but...

For years when we ground in 2 valve heads we always put a round headed chisel on the centre of the valve and gave it a LIGHT , and I repeat LIGHT, tap with a hammer. It helped seat the valve fully for testing..

Nowadays with modern multivalve heads with tiny exotic valves we don't do this.

oldzed wrote: Some will not agree with this but...

For years when we ground in 2 valve heads we always put a round headed chisel on the centre of the valve and gave it a LIGHT , and I repeat LIGHT, tap with a hammer. It helped seat the valve fully for testing..

Nowadays with modern multivalve heads with tiny exotic valves we don't do this.

You fooled yourself if you think that did anything helpful.