CB750 sohc K5 head skimming?

[martin_uk]

Helping a friend with his bike and depressions have formed where the head gasket combustion rings contact the head.

I have not come across this on my CB750 bike rebuilds and would appreciate views and experience.

Is it OK to lightly skim head and what is limit?

Has anyone experienced this before and likely cause?

The combustion rings on new gasket will help seal the extra gap caused by grooves, but what is the limit?

Views and thoughts appreciated.

[Bryanj]

To me that has been overtightened, personaly i would ask Mark Paris(hondaman) on the us forum as to maximum skim

[martin_uk]

To me that has been overtightened, personaly i would ask Mark Paris(hondaman) on the us forum as to maximum skim

Thanks Bryan

[McCabe-Thiele (Ted)]

There were some marks on my 500 cylinder head, difficult to measure the depth of the imperfections, one was where the main seal ring is for the cylinder head.
Local machinists said they would take the minimum required to remove the marks. When I picked up the head the finish was like a mirror.

I asked how much material had been skimmed, less than 5 thou of an inch!
The firm are known locally  primarily as diesel fitters & engineers.
Service Garage Borrowash.
They have a website now.