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Discussion Starter · #1 ·
Hi,
I have reached the point on my CB200 cylinder head refurb of ordering new valve guides. I have looked on the CMS web site and they give the same part number for both Inlet & Exhaust, Part No 12021-354-405 which has superseded the original part numbers, which differed for inlet & exhaust. Does anyone know if it's ok to use the same guides for both inlet & exhaust or is it an error by CMS.

Many Regards,
Glyn.
 

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Discussion Starter · #3 ·
Hi Nige,
Yes I have already seen that link but it doesn't help much. It is just that my parts catalogue gives two different Part No's for inlet and exhaust, 12021-354-300 and 12023-354-300. Perhaps they just decided to use the same guide for both, but not sure.

Glyn.
 

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I don't know about these engines, but as far as I know, the guides are normally all the same, and I see no reason why they would use different ones. Perhaps you could only mount the valve stem oil seal on one, and the other would not be sealed?
 

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According to the FSM, it looks like Honda wanted the exhaust valves to fit a little looser than the intake valves so the guides are different. The intake guides may still work on the exhaust as long as there's enough clearance.

.......Paul
 

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Discussion Starter · #7 ·
Thanks for all the input on the guides. It looks like I'll have to try running with all the guides the same as I can't find a supplier that sells the two different types.
Regards,
Glyn.
 

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Thanks for all the input on the guides. It looks like I'll have to try running with all the guides the same as I can't find a supplier that sells the two different types.
Regards,
Glyn.
A quality machine shop will hone the bores to fit precisely for both intake and exhaust valves so you have a relatively tight,low-friction fit.
 

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Though they're not tough to install, new valve guides are NOT ready to go out of the box.
Once installed, they need to be sized with a precision reamer - a machinist would take care of it for you.
 
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