Author Topic: Newly ground valves in wrong holes - opinion  (Read 1294 times)

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Offline finkbuilt

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Newly ground valves in wrong holes - opinion
« on: June 05, 2011, 01:20:02 PM »
More opinions  on my stupidity sought.

So, I took all the valves out of my cb350F head, cleaned everything, and performed a valve grind.

But when I was about to reinstall the head, I noticed that I had numbered the head incorrectly with a sharpie, so, I think that I have put the valves back in the wrong holes.

Do I need to redo this head? or do you think that it will be alright?

The "gray stripe" on the bevel cut area of all the valves, and ports looked even and consistent.  Aren't they all going to be essentially identical and interchangeable then?  I'd like not to have do it all over again. I dont think that the new seals would survive being taken off to do another grind. (I can't be certain at this point which ones were ground to which holes)

-steve

73 CB350F

Offline OldSchool_IsCool

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Re: Newly ground valves in wrong holes - opinion
« Reply #1 on: June 05, 2011, 01:28:57 PM »
Grinding valves takes some pretty sophisticated equipment.  Do you mean to say that you LAPPED your valves with a lapping compound or did you actually machine them? 

Ideally, the valves should be returned to the seat from which they came.  Can you figure out which seat they should be moved to with certainty?
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Offline MCRider

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Re: Newly ground valves in wrong holes - opinion
« Reply #2 on: June 05, 2011, 01:37:53 PM »
Grinding valves takes some pretty sophisticated equipment.  Do you mean to say that you LAPPED your valves with a lapping compound or did you actually machine them? 

Ideally, the valves should be returned to the seat from which they came.  Can you figure out which seat they should be moved to with certainty?
Yeah we're thinking you lapped them not ground. If ground, must be in same hole. If lapped, check for leaks. Turn head on exhaust side, prop up, fill intake ports with solvent, kerosene or the like. If it leaks thru to the combustion chamber, well...

Same on Exhausts. any leaks, mean relap, or relocate.
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Offline finkbuilt

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Re: Newly ground valves in wrong holes - opinion
« Reply #3 on: June 05, 2011, 01:57:31 PM »
Quote
Yeah we're thinking you lapped them not ground. If ground, must be in same hole. If lapped, check for leaks. Turn head on exhaust side, prop up, fill intake ports with solvent, kerosene or the like. If it leaks thru to the combustion chamber, well...

Same on Exhausts. any leaks, mean relap, or relocate.

yes, I meant lapped.

I used permatex silicon carbide valve GRINDING compound, which I guess is why I called it grinding I guess.  I hope that was the right product.

anyway, They all seem to hold solvent. 

I thihnk that it was a bit of a false alarm.  To make a long story short:

When lapping,  I used the numbering on the rubber intake boots as a reference.  Then I flipped the head over and wrote those corresponding numbers on the head to keep it straight. 

My confusion arose when i noticed that the numbers on the opposite sides of the boots were "backwards", and the numbers that I had written were backwards with regard to the actual cylinder numbers. 

Simply put, I now believe that I put them back into the holes into which they were lapped.  Although my numbers did not actually correlate to the actual cylinder numbers the way we normally think of them.

-steve
73 CB350F