Valve Leak

I'm doing a top end rebuild on my KZ. I took off the head and filled the ports with solvent. The solvent slowly seeped out past the valves. I took it apart and upon inspection of the valves and seats I didn't see any pitting. The valves looked new after the wire wheel. I lapped them in a bit to see if that would help. After reassembly the solvent isn't leaking past the valves anymore. However, when I blow compressed air around the valve seat I can see a couple of tiny bubbles come up.

My options are take it apart again for another round of lapping

Or I could send it out for a proper valve job

Or say "good enough" and run it as is.

Should there be absolutely no leakage or are the tiny bubbles acceptable? I'm not rebuilding for performance but I'm not trying to half ass it either.

The bike ran before the tear down. I had 100 psi in the low cylinder and the plug looked a bit oily.

Also, do the valves seat in/bed after running the motor to seal up more?

Thanks

Are you blowing air into the exhaust/intake runners and seeing bubbles in the combustion chambers? You could be forcing the valves open slightly with the air pressure and causing the bubbles?

Sounds like he filled the port and blew air around edge of valve face and seat,Thats how I do it also.
If it was me Id take it back apart and grind them just enough to get them straight,then lap them some more.
Don't forget to check guides and replace seals while its apart

Yes, I was blowing air around the edge of the valve face, not through the port.

The guides don't have any discernible wear. The valves are a good fit with basically no side to side movement in the guide. I replaced the guide seals with new Viton seals. It was a pain for the first couple, but I found a good way to get them on.

I suppose I'll do what I should have done the first time and have them cut. I've gone through a lot of trouble to not have it how I want it.

Thanks for the help.

Its all part of the learning curve

Spectre1982 wrote: Yes, I was blowing air around the edge of the valve face, not through the port.

The guides don't have any discernible wear. The valves are a good fit with basically no side to side movement in the guide. I replaced the guide seals with new Viton seals. It was a pain for the first couple, but I found a good way to get them on.

I suppose I'll do what I should have done the first time and have them cut. I've gone through a lot of trouble to not have it how I want it.

Thanks for the help.

After you do that, your lash is going to change. How much depends on how heavy the valves are faced. The valves need tipping after the face cut unless you had really thick shims in there before hand.

If you want to see the true contact pattern of the valve to the seat, use dykem or magic marker. Don't spin the valve when you do that. It will mislead you.

That's a good point.

I'm factoring that in. I'm sure all of them will be out of spec. I'm going a bit over budget for my project, but I sure know my engine well!!! :silly:

Spectre1982 wrote: That's a good point.

I'm factoring that in. I'm sure all of them will be out of spec. I'm going a bit over budget for my project, but I sure know my engine well!!! :silly:

A light face cut can sink the valve .010" real quick....

Finally got around to putting everything back together. After the valve job, I needed six new shims. All the clearances are set right at the max. It ticks over like a Swiss watch. I put 50 miles on it and the motor feels great. Compression is even across all the cylinders and it hasn't blown up on me yet.

Thanks for all the help!

Good Deal