Out of intake valve clearance

It would seem my RH intake valve is stretching (tuliping, we used to say).
It's the third time it needed adjusting in just a couple thousand miles. When it tightens up it won't start with the button, but it will pull start. Did that at two bike rallys, I didn't shut it off all the way home once it was running.
This time my smallest feeler gauge wouldn't go in. Had a 1.35mm shim under the bucket.
Got a 1.20 from a local shop, they said that is the shortest one available.
Was still tight, maybe .05mm (should be .13-.20mm).
Put the bucket on without any shim, started right up. not really any noisier than usual, does have an FMF exhaust. But I expect the valve will break off before very many miles.
So the head needs to come off, not something I really want to do. I expect to sell it as is, worth $2500 or so?

on2wheels52 wrote:

So the head needs to come off, not something I really want to do. I expect to sell it as is, worth $2500 or so?

If you're willing to sell it for $2500, this means you regard the engine as a total loss. Even if you're not willing to do the job yourself, a shop will charge you far less than $2500 to replace a couple of valves.

ok, ok, I can take a hint

whats the story on the bike, why did valves fail, overheated, failed air filter, now since you need new valves you should put a athena big bore kit

on2wheels52 wrote:

ok, ok, I can take a hint

Have you been able to determine which component wore out? Valve, valve seat, shim, bucket?

Dropped the head off this morning, he called and said the RH intake needs replacing and would like to do the LH also.
Seats and the exhaust valves look ok.
However......
The aftermarket part sources he uses don't have a listing for them. He can get them from Yamaha for $150/each. He thought
that was rather high.
Does anyone here know of a reliable source? (or have a pair sitting around )

Valves are available at ServiceHonda for $126 each; they may seem expensive, but that's the price of titanium.

Which makes me question the mechanic's conclusion that it's simply the valve that failed; given the titanium valves, I would expect the valve seat to have been worn more than the valve itself. Did he provide measurements so you can check against the tolerances in your service manual? (page 5-20)

Thanks for the link John!
I'll ask how he determined it was the valve rather than the seat.

Valves came Saturday, dropped them off this morning. He gave me the old ones.





The LH maybe has some life left; the RH is concave where it seats. Wore right to the edge.

on2wheels52 wrote:

The LH maybe has some life left; the RH is concave where it seats. Wore right to the edge.

I've only seen damage like this on dirt bikes that were consistently raced in very dusty conditions; did you ever notice the air filter not being fully seated?

Given this extreme wear of the valve, there was no corresponding wear of the valve seat?

The last motorcycle valves I looked at was in the '70's

But no, I have not had any issues with the air filter.
But what if......
Let's say I ran it in the dust with no air filter installed. Wouldn't BOTH valves have similar wear?

The guy with the shop said all the valve seats were ok, just needed to be cleaned up. It was done when I brought him the valves.
The seats looked fine to me but that's not something I know much about.
He said I may have to re-shim the exhaust valves as well as the intakes.

Waiting for the next rainy day to put the thing back together.

on2wheels52 wrote:

Let's say I ran it in the dust with no air filter installed. Wouldn't BOTH valves have similar wear?

The guy with the shop said all the valve seats were ok, just needed to be cleaned up.

Yes, all else being equal, dust going past the air filter would affect both valves the same. But if one valve was tighter than the other, it could have deteriorated more.

Which brings the second point: the valve seats needed cleaning? Valve seats shouldn't gum up since they are being struck by the valves dozens of times per second; the only exception is if there wasn't enough valve clearance, which is what you originally reported. So it appears that what must have happened is that the RH valve got tight, was not sealing against the valve seat, exhaust gases were heating it up, thus weakening it and depositing gunk on the valve seat, and that gunk on the valve seat in turn gave the valve edge that concave shape.

In an older thread you had mentioned that you had close to 40k miles on the bike. How many times had you adjusted valves prior to this incident?

re cleaning the valve seats, perhaps that's not the right term. How about touched up or lapped? They didn't have carbon
deposits if that's the thinking.

I bought it in '15 with 21k miles, am at least the third owner. I checked the valve shortly after, they were in spec.
Should be good for another 26.6k, right?

I rode it to SLAP in '21, ran great but then wouldn't start when I went to leave Sunday morning. Just cranked and cranked.
But it pull started. Started fine when I stopped for gas and breakfast.
But it wouldn't start the next morning (and didn't want to teach my wife how to pull start )

Checked the valves (at least one needed a new shim, I assume it was the RH intake but I didn't make a note of that.
Was 8/1/21, 38,742 miles.

(now that I think about it, I think I had to do another valve adjustment between these two, but I wasn't on the road when it
wouldn't start)

Ran great again. In September I rode it 4 hours to an MTRA event in MO. Deja vu all over again. Wouldn't start when I wanted
to head home. But got another pull and left. I could tell it wouldn't self start this time (turned it off coasting on the highway, wouldn't go with the starter). I knew I'd have to get gas, couldn't make it on a tank. It died when I clutched at the gas pump.
But the guy in a Ranger next to me had a rope and away I went.

And that brings us to the current state.

Lapping is something that must be done to the valve seats when replacing valves, but as per the service manual, the valve seats need to be lapped using the valves themselves; unfortunately, too late for that now.

That timeline is troubling: within a year of adjusting the valves, they were out of adjustment again. Hopefully this was a one-off defective valve, and now you'll be able to go 26k without having to think about adjusting them again.

that seat is damaged, I don't even have to see it... when you have a valve that is that wobbed out, the seat needs to be re-cut. lapping might work, but thats really not the right way to fix it. lapping is for a fine adjustment, and properly cut valves & seats do not need lapping at all. in fact, valves made of exotic materials are often coated, and lapping damages that coating resulting in short service life. most manufacturers of coated valve specifically say do NOT lap. the typical coating is chromium nitride... it is about 3-4 micons (0.000118")

you will need to check the distance of valve tip above the spring seat (or some similar reference point). after the seat is cut, the valve will sit "taller" above the guide... if it is too tall, there may not be an adjustor shim small enough to give proper clearance. the manual will give this spec. if that is the case, or if the clearance runs near the limits, the valve can be "tipped".... grind off some of the tip to give more clearance. again, the specs will tell you how much can be removed. every valve grinding machine has an attachment for this

I am new to the WR but have many years working on machines and doing machine work. fwiw... I have tested valve adjusting shims by grinding away 1/2 of the thickness, then shooting them with a Rockwell tester. they are the same hardness in the middle as on the surface. I have ground shims on a surface plate, I have ground them on a sheet of glass with wet/dry sandpaper in order to make a fit. it works

It fired up fairly quickly when re-assembled (given that it hadn't run for 6 months).
I don't know what to say about the seats, they looked ok to me but then I'm no motor guru.
I'll see how the next few thousand miles go.
Thanks for building a fire under me john, it's a lot better off road bike than my CRF300.

I'd say check the valve clearance after 6k, if it hasn't moved, enjoy it for another 20k.

Incredible how a 15-year old bike is still better than all other small bore machines.