Would you replace or run them?

Here are some pics of my valves from my 02 426. I am giving the top end a refreshening and wanted to inspect the valves while I replace the piston (which had no wear). I measured the valve seat width, stem O.D. and both measured like new. The manual gives runout as well as "new" specs and all 5 were very close to "new" specs and nowhere near runout. The seat width does look a little bigger in the pics due to lighting however. The tips are multicolored telling me that some of the coating has worn but not all. I have never had to adjust any of these and have never had any hard starting problems. The clearance all measured within spec although it was closer to minimum spec rather than in the middle. Tell me what you would do.

P2010191.jpg

P2010190.jpg

keep them as you say these are close to new, I'd manually regrind the seats if needed just to have them tight (petrol/ spirit test)

Here are some pics of my valves from my 02 426. I am giving the top end a refreshening and wanted to inspect the valves while I replace the piston (which had no wear). I measured the valve seat width, stem O.D. and both measured like new. The manual gives runout as well as "new" specs and all 5 were very close to "new" specs and nowhere near runout. The seat width does look a little bigger in the pics due to lighting however. The tips are multicolored telling me that some of the coating has worn but not all. I have never had to adjust any of these and have never had any hard starting problems. The clearance all measured within spec although it was closer to minimum spec rather than in the middle. Tell me what you would do.

P2010191.jpg

P2010190.jpg

I'm not a valve expert, but I was curios as to the fact that your piston showed no wear on an 02 426. I have three years on my 05 450, and about maybe about 2500-3000 miles and was wondering if I should follow the book and rebuild the top end.

It still has plenty of power. Maybe its lost just a little snap. But I also may be a better rider and able to control it more.

Do you feel like you really didn't need to do the top end on the 426 after looking at it?

Id clean them, check for leaks, and run them. As far as the clearances go, I think the tight side of the middle of spec is OK. You amy want to reshim is you have, for example a 172 insatlled, and you could go down to a 170. I'd be more concerned with the exhaust side though. My .02

I'm not a valve expert, but I was curios as to the fact that your piston showed no wear on an 02 426. I have three years on my 05 450, and about maybe about 2500-3000 miles and was wondering if I should follow the book and rebuild the top end.

It still has plenty of power. Maybe its lost just a little snap. But I also may be a better rider and able to control it more.

Do you feel like you really didn't need to do the top end on the 426 after looking at it?

As far as the cylinder and piston go? Yeah I feel like I didn't need to do it because they look as "like new" as they can be for the use. I probably have over 200 hrs on the bike maybe more I don't have an hour meter and I took of the odo so I'm not sure of the mileage either. But I really wanted to inspect the valves because of all the stories I've heard. The cylinder still had most of the original cross hatching and not much glaze. So I just cleaned it up with a scotchbrite pad and am going to run it with a new piston/ rings like that instead of honing. There are different opinions about honing nikasil cylinders. Since mine was in good shape I'm going with what Eric Gorr recomends (among others) and using the scotchbrite method.:)

Id clean them, check for leaks, and run them. As far as the clearances go, I think the tight side of the middle of spec is OK.

this is what we did on my dad's 06 that had 11k miles on it when we did a rebuild...they stock valves were and are on the stock shim pads....:lol::)

Reinstall the valves and pour kerosene in the intake and exhaust ports. If any kerosene leaks out around the valve seats, give them a light hand lap. I think I'd lap them anyway since you already have them out.

I think I'd lap them anyway since you already have them out.

you DO NOT lap TI valves:bonk:

you DO NOT lap TI valves:bonk:
No, you don't. Not ever. Not under any circumstances.

The nitride coating on Ti valves is very often less than .0004" (.01mm) thick. Damage it, and you're done.

you DO NOT lap TI valves:bonk:

This is correct. I was thinking steel valves, brain fart.:)

This is correct. I was thinking steel valves, brain fart.:)

Can't get rid of you, can we?:lol:

Can't get rid of you, can we?:)

Welll...the WX here is really crappy, nothing much else to do. Heading for FL in 3 weeks with both the street and dirt bikes, life will improve exponentially.

Create an account or sign in to comment

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

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now