Valve Guide Reamer Recommendation

[YL82]

I learned that a .3145" straight-flute reamer worked fine for my valve guides on the Exhaust side, but I had to order/use an 8 mm reamer for the valve guides on the Intake side since the Intake Valves would not begin to go through the guides after reaming with the 0.3145" reamer. I wondered whether I had ordered the proper Intake Valves (i.e., new OEM from EBay).

i had not realized that the OEM Inlet Valve Stem Diameter is slightly larger than the Exhaust Valve Stem Diameter.

From Haynes Manual:

Inlet Valve Stem Diameter: 7.795 - 7.990 mm (0.3140 - 0.3148")

Exhaust Valve Stem Diameter: 7.960 - 7.975 mm (0.3134 - 0.3140")

So, the ID's for my guides on the exhaust valves are a little snugger than they otherwise would have been if I had used the 8 mm (0.31496") reamer on them. Not a bad thing I suppose.

 

[Olie]

Hugh measured OEM exhaust valves and found just that. From Hugh:

35 Year Old Stock XS650 Intake Valve Measurements

Bottom of valve stem - .3141"
Middle of valve stem - .3141"
Top of valve stem - .3141"

Pretty Consistent Measurements on that valve.

35 Year Old Stock XS650 Exhaust Valve Measurements

Bottom of valve stem - .3136"
Middle of valve stem - .3136"
Top of valve stem - .3136"

Just make sure you have the proper clearance when you're done. According to Kibblewhite, the valve to guide clearances should be:

Intake: 0.0008" to 0.0012"
Exhaust: 0.0011" to .00150"

That's for their stainless or titanium valves with cast iron or bronze guides. I don't have my manual in front of me so I don't know what Haynes suggests. Hope this helps

 

[YL82]

Thanks, Olie.

 

[Rude456]

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