Jump to content
Sign in to follow this  

Exhaust Valve Clearance

Recommended Posts

I just checked my valve clearances and neither the intake nor exhaust valves have moved since I shimmed them last year. My intakes are dead on spec at 0.005", but my exhausts are at the high end at 0.012". Question is, should I change the exhaust shims to achieve 0.011" or even 0.010"? I seem remember some saying they have the exhausts at either the low end or the high end of spec, but don't remember which and why.

Share this post


Link to post
Share on other sites

I didn't mess with them. I am simply curious if it's better to run them on the tight or loose end of spec, or dead on. I already have a shim kit so swapping them out is no biggie.

Edited by mossman77

Share this post


Link to post
Share on other sites

I think most prefer the loose side, but my point was, .001 to "spot on" is not a big difference.  Neither is .002 for the complete range of the spec.   I'd highly doubt you'd notice a difference no matter which way they were.

 

Being on the high side gives you a tad more wiggle room if they do start to get tight though, but if your staying up on maintenance, you'll find out their moving before you have a problem anyway.

 

Jim.

Share this post


Link to post
Share on other sites

One of the reasons some like to run tighter clearances is because the valve lifter will stay on the cam longer and the valve will be set down on the seat a little easier, so not quite as much impact to the seating surfaces.

Another reason would be to get slightly more lift and duration from the cam lobe to enhance performance.

I prefer .004 on the intake side and .009 on the exhaust side.

Share this post


Link to post
Share on other sites

 All true and I've heard it both ways.

 

 Personally I shoot for the middle of the spec and if I'm in the spec when done, then it's a done deal no matter which side it's on.

 

Jim.

Share this post


Link to post
Share on other sites

Not trying to high jack the thread but my kids bike, an 06 250x is needing shim adjustments after every 15 to 20 hours of riding.

Is this normal?

Had the head redone last year. Could this be the sign of something wrong ?

Rebuilt with titanium valves if I remember right and it seems to always be the same valve that's needing shims.

Edited by Fyrflie

Share this post


Link to post
Share on other sites

Yes, this is common for the 2006 and earlier models. Honda changed the valve seat material in 2007. You need to have the seats replaced or install stainless valves.

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...