Valve Guides

[Anonymous]

When I did some work on the head I noticed that the valve guides protrude a long way into the inlet and exhaust ports. This must restrict the gas flow and cost power. 8O
Has anyone ground down the guides so that they are flush with the port? :twisted:
If so does this give much increase in power? Does it effect valve/valve guide/valve seat life?
:?:

 

[SqDancerLynn1]

DON"T DO IT

 

[cbxchris]

From experience it can be a good thing to shorten them but not completely grind them off. I like to shape or taper them so as to help air flow. Its usually a mistake to completely remove them unless its in a drag bike.

 

[Anonymous]

Has anyone ground down the guides so that they are flush with the port?

Not personally, but it is done often in race motors.

If so does this give much increase in power?

Not a huge increase, but a bit. Maybe useful on an all-out race motor, but not worth it on a street beast. You will get way more power with new carbs or a big-bore kit.

Does it effect valve/valve guide/valve seat life?

Yes indeed. Depending on how much you remove, it can very significantly shorten guide/seal life.

Check out this page for some interesting porting info and a better way to do it if you want to take a Dremel tool to your head:

http://mototuneusa.com/thanx.htm

Read articles #16-20 for a complete description and pictures. A nice winter project...

Mark

 

[Dink]

http://mototuneusa.com/thanx.htm

Read articles #16-20 for a complete description and pictures. A nice winter project...

Mark

Oh Thanks :? you took me away from our beloved GSResources for over three hours reading that site!!! :? :wink: :lol:
Dink

 

[Anonymous]

Oh Thanks you took me away from our beloved GSResources for over three hours reading that site!!!

No problem, Dink. It's an interesting read and he has a unique viewpoint.

Mark