Valve Seals?

[LoHo]

I did it more old school.
Homemade tool with head removed:

Keepers out:

Needle nose pliers to pull out old seals:

Seat new seals with the open end of a 6in1 screw driver:

[mack]

Compression

If you pull the valves , clean them and lightly lap the valves and seats together. Do the fluid test on the valves and seats and lap a little more on the ones that leak a bit before you re-install the head. Once everything is seated properly, check your shims one cam at a time with the head elevated off the table. Once this is all done then install the head and check your compression. You'll need to retune your carbs to the valves once it's breathing properly. You'll probably notice a big performance difference.

[MPittma100]

Valve Seals

If the bike has considerable miles on it and we don't want to discount the age of the engine, I would run a cylinder leakage test to determine the percentage of leakage and what the leak(s) is/are - valves, rings, head gasket etc.

I am in agreement that you will be best off removing the head and having it reworked by a competent machine shop. You would also take them the camshafts and bearing caps/bolts so they can adjust the valves along with the repair. This way you have a fresh start on an old motor.

If the leakage test is over 15%, you may have also be in need of rings.

MP

[crazy steve]

You want to be extremely careful about having machine work done on the valves. You only have a limited range of adjustment available, take too much material off either the valves or the seats and the head can end up being junk because you won't be able to find thin enough shims to properly adjust the valves.

Most just lap the valves to the seats. But before doing any grinding, check your shim thicknesses; if you have any that are below a 250 shim size, you only have .020" of clearance or less to play with. Total adjustment 'range' (thickest to thinnest shim) is only .048", not a lot. Remember that as the valves wear (or are ground), clearances are reduced requiring thinner shims...

[CaptonZap]

Howdy Steve,

The machine shops that I know of that have old timers working the machines, all have a pretty good idea of how much to grind off the tip of the stem to allow for the recession of the valve into the seat.
Without that knowledge, your point is a good one, and, I may be off base here because I haven't had an 11 valve apart, so I don't know how the bucket/stem interface works.
With that in mind, the height of the stem tip could be measured before teardown, and again after the seats and valve were ground, and the appropriate amount taken off of the tip. Not knowing if the tips are surface hardened, and how deep, would be another point to ponder.

JAT, CZ

[crazy steve]

I don't think you can grind the stem any shorter, as that will upset the stem/bucket interface. IIRC, somebody tried that and the bucket ended up contacting the valve spring retainer rather than the valve, seems to me that resulted in a dropped valve...

What you would need would be a custom valve with the retainer groove on the stem relocated closer to the valve. Either that, or reduced base circle cams. The latter may be easier to come up with, but neither would be cheap...

The big problem here is most of these 'fixes' will cost you far more than just getting another head in better shape. I know, at some point the good used head supply will dry up and we'll have to start biting the bullet if we want to keep these bikes on the road....

[CaptonZap]

[QUOTE=crazy steve;400068]I don't think you can grind the stem any shorter, as that will upset the stem/bucket interface. IIRC, somebody tried that and the bucket ended up contacting the valve spring retainer rather than the valve, seems to me that resulted in a dropped valve...

What you would need would be a custom valve with the retainer groove on the stem relocated closer to the valve. Either that, or reduced base circle cams. The latter may be easier to come up with, but neither would be cheap...

QUOTE]

Haw, I'm ready with my surface grinder.
I can make those shims thin enough to wrinkle.
I found that I can get the clearances with in .0005 without to much trouble.
CZ

[TomB]

Haw, I'm ready with my surface grinder.
I can make those shims thin enough to wrinkle.
I found that I can get the clearances with in .0005 without to much trouble.
CZ

HAHAHA! not just me then
In 30 years of XS1100 ownership I've never bought a shim yet, just keep grinding them down where needed, my first XS1100 still has its original shims that Yamaha fitted in the factory, they're not necessarily the same size but they are the originals



.

[CaptonZap]

HAHAHA! not just me then
In 30 years of XS1100 ownership I've never bought a shim yet, just keep grinding them down where needed, my first XS1100 still has its original shims that Yamaha fitted in the factory, they're not necessarily the same size but they are the originals



.

Way to go, Tom.
I don't know if you mark yours, but on mine I take a toothpick and chew the end to fuzz it up. Then I dip it in battery acid and use it like a pen and print the thickness on the ground side. Let it set for a few minutes, rinse it off, and presto, indelible marking. Until the next time you grind it.
How thin have you ground yours, and how thin do you think you can go before flexing will become a problem? And how close do you get your clearances?

CZ

[Bonz]

You geezers with more time and tools on your hands than you know what to do with....

You guys fill your own teeth as well? Heh, Heh, Heh...

[Schming]

You geezers with more time and tools on your hands than you know what to do with....

You guys fill your own teeth as well? Heh, Heh, Heh...

Now that's funny right there, I don't care who you are !!!

Thanxs for the laugh

[CaptonZap]

You geezers with more time and tools on your hands than you know what to do with....

You guys fill your own teeth as well? Heh, Heh, Heh...

All right, you cocky youngster. You just mind your lip, and pay attention, and some day, when you get all growed up, you will be able to do the things we do. CZ

[Bonz]

I'm not a cocky youngster, I'm a young whipper-snapper.

And I promise I'll never surface grind a shim as long as my friendly neighborhood dealer keeps swapping with me.

[crazy steve]

The original post was about the valve stem seals, we've kind of gotten off the path here....

One thing not discussed is valve stem to guide clearance. This needs to be checked, because if it's out of spec badly new seals won't last all that long. And if it is out of spec, your choices for fixing it are limited. Valve stem diameter needs to be checked, if you have excessive wear the only real choice is new valves. I've seen the stems reground undersized with either guide inserts installed or knurling done, but the stems are usually surface-hardened. Grinding removes this and accelerated stem wear is the result, with valve failure a possibility; it's happened to me on a car motor...

These motors aren't all that 'rebuild friendly' if you're trying to get back to OEM specs. Not to say it can't be done, but the $$ investment can be pretty steep...

[CaptonZap]

The original post was about the valve stem seals, we've kind of gotten off the path here....

One thing not discussed is valve stem to guide clearance. This needs to be checked, because if it's out of spec badly new seals won't last all that long. And if it is out of spec, your choices for fixing it are limited. Valve stem diameter needs to be checked, if you have excessive wear the only real choice is new valves. I've seen the stems reground undersized with either guide inserts installed or knurling done, but the stems are usually surface-hardened. Grinding removes this and accelerated stem wear is the result, with valve failure a possibility; it's happened to me on a car motor...

These motors aren't all that 'rebuild friendly' if you're trying to get back to OEM specs. Not to say it can't be done, but the $$ investment can be pretty steep...

Sorry, Dad

I haven't seen any call outs on stem clearance, but on some of the engines that I have worked on, the quick and dirty check for stem wear was to remove the spring, extend the valve out from the seat the valve lift distance, and check the side play at the valve head. Does Yamaha give any such measurments in the big shop manual?
The fact that the bucket takes all the side ways force of the cam wipe, would make it seem that there is not much side force on the stem. Which would be a factor in low stem wear. If the valve stem recieved lubrication, it shouldn't wear a lot. Which would mean that the stem seal is keeping oil from getting to the stem, and the addition of two stroke oil, Marvel Mystry oil, or any of the other upper cylinder oils added to the gas would be a good idea for those interested in prologing the life of their engines.



Hows that for on topic, Boss?

If it would quit snowing, I would go do something and leave you guys to your own devices.
Later, CZ