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Dohc cb750 valve contacts

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Jimboslice

Dohc cb750 valve contacts

Hi all. So i got my head back from the machine shop yesterday after having the seats cut for new valves and after inspecting the valve to seat contact, i find that the contact is at the bottom of the face and about .025 over in width. Is this ok or do i need to go back to the shop and have them re do it?

1982 cb750k
If it aint broke. Fix it till it is

TOOLS1

Re: Dohc cb750 valve contacts

Administrator

I have done hundreds of Honda valves and that is how most of them turn out. Honda for some reason has large diameter holes in the valve seats and small diameter valves. Did the machine shop assemble the head or did you just take them a bare head?
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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Jimboslice

Re: Dohc cb750 valve contacts

Thanks tools. I brought them a bare head and the new valves. And a copy of the valve specs per the shop manual. Should i just run it?

1982 cb750k
If it aint broke. Fix it till it is

TOOLS1

Re: Dohc cb750 valve contacts

Administrator

I would. If you had them cut more material out of the throat of the seat you would end up with a very narrow seat area that would seal very well, but not last as long as the wider seat area.
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