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Author Topic: Valve guides protruding into port  (Read 1112 times)

Offline MJ Williams

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Valve guides protruding into port
« on: April 28, 2016, 05:42:56 PM »
I've just had the valve guides in a Gen II cylinder head replaced.
The old guides in the head had been pressed down then ground to match the contours of the ports.
This time the machinist left the guides protruding in to the ports.
He says that it really doesn't make much difference in air flow to not contour them to the port but makes for better accuracy when cutting the seats on the next valve job. The second part makes sense.
Frank has been doing heads for 25+ years but isn't a Hayabusa guy. He has a flow bench and builds lots of R6 heads for roadrace guys and has built some bad-ass CR450F engines where he does all the porting etc.
He does gorgeous work and I'm really happy with his workmanship. Just wondering for myself if there is a worthwhile difference in contouring the guides to the port in a Hayabusa.
Thank you, Mike
Have a Harley, spent lots of money on it, thought I had a fast motorcycle, bought a Busa, realized all I had was a fast Harley, not a fast motorcycle!

Offline Jay

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Re: Valve guides protruding into port
« Reply #1 on: May 05, 2016, 02:23:19 PM »
You got answered on psychobike

Offline MJ Williams

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Re: Valve guides protruding into port
« Reply #2 on: May 06, 2016, 11:39:55 AM »
Thanks Jay, I had posted it in both sites on the same day. :tu:
Was down just a touch on hp after the rebuild and was looking at a couple things to cause it.
Did find out what it was.

Have a Harley, spent lots of money on it, thought I had a fast motorcycle, bought a Busa, realized all I had was a fast Harley, not a fast motorcycle!

Offline speedduck

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Re: Valve guides protruding into port
« Reply #3 on: May 06, 2016, 01:37:18 PM »
So, was it the guides ?

Offline MJ Williams

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Re: Valve guides protruding into port
« Reply #4 on: May 06, 2016, 03:27:11 PM »
No, issues with my STPs.
Have a Harley, spent lots of money on it, thought I had a fast motorcycle, bought a Busa, realized all I had was a fast Harley, not a fast motorcycle!

Offline speedduck

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Re: Valve guides protruding into port
« Reply #5 on: May 07, 2016, 07:04:34 AM »
Ok, thanks. I been thinking about the same thing, if it was better to leave the guides unmodified.