Valve shim Shave?????

After reading a few shim posts I became curious and started pricing.
Im not saying its a rip off but surely a guy can shave the tight shims to the desired tolerance.
Success or warnings post here.

 

In years past I have done this but you must have a surface grinder. You can not use a bench grinder since you will not have any success in making the valve shim flat and parallel. Also you must not remove any heat treating process that was on the valve shim. Do not overheat it while grinding it. Also when you place the shim back in the bucket, place the ground side down. If you do grind the shim down, grind off the size dimension that is on there. I did this years ago when I was broke and had a machine shop surface grinder at my disposal. Now if I was to do it again, I would just purchase the shims that I needed.

Sean

 

New shims are cheaper than fixing a ruined head and cams. Those are percision machined parts, cheaper to replace them and keep the old ones just in case.

 

Most Motorcycle Service Departments have a Bucket or some Bins with Shims that are perfectly good.

Bring-in your Shim and know the Number you NEED.

Ask if you swap yours or buy a used one.

 

Thanks for the tips. We have a Yamaha dealer in town. I hope they work with me a little.

 

NO NO NO. Shims are only surface-hardened; grind them and you'll compromise them.

One of our members with access to advanced metallurgic technology recently did a cutaway with electron-microsocope pics, Rockwell testing, the whole 9 yards to prove once and for all IT AIN'T A GOOD IDEA.

Chacal sells aftermarket shims for half of what Yamaha gets.

 

I'm trying to find a cheaper way to get valve shims -- the ones I need aren't 29mm like the Maxim/Seca's -- they're 25mm. Of course they're different. OF COURSE. /facepalm

The Yamaha dealers in my area have been zero help so far!

 

Bill, what size shims do you need?

 

Im gearing up for this project. Its gonna suck having my bike apart trying to hunt down the correct size shims though.

 

You don't have to "hunt down" shims, just order the correct new ones from Len and be done with it.

Do you also know what kind of mechanical train wreck it would cause in the cam gallery if that "home hardened" shim SPITS at 9K rpm?

Guys, this isn't a difficult process, it's part of normal maintenance. Every 5000 miles. It's something you have to learn, because if you keep the bike for a while, you'll be doing it with some regularity, depending on how much you ride. I've done my '81 twice now in the 9000 miles I've put on it; and once on my '83 (which will be due again sometime this summer.)

Don't make it into a bigger deal than it really is.

 

Bill, if you don't mind going with used shims, I have a small collection in my possession.. Also, the guys at Rons Cycle will sometimes let me trade shims.

 

You are right.

 

I didn't realize you were in Tulsa too. Howdy neighbor!
Great info, we should go for a ride sometime.

 

Sounds good! I'd never pass an opportunity to burn some fuel :mrgreen:

 

All right ... once again, for the record, the valve shims are hardened and nitrided. The nitriding on the OE shims is about .0002" thick. The nitriding on the aftermarket shims is actually thicker but they use a different form of nitriding. The aftermarket shims have nitriding in the neighborhood of .002". If you opt to grind the shims, there is no way you can ever know whether or not you went through the nitriding layer because it can only be measured by cross-sectioning the shim (cutting it in half).

If you do happen to grind through the nitriding is it the end of the world? Probably not. The shims are D2 tool steel and they are hardened and then tempered to about Rc 56. But they will wear much quicker without the nitriding. The nitriding is an extremely wear-resistant surface and the shims are nitrided AFTER GRINDING!!!!

I find it interesting that DINORACER even found a shop that would grind them for him. They must have owed him a favor or maybe he let them put their name on his jersey or something. I have a tool shop and there is no way that I would grind a handful of shims cheaper than you could ever buy them from Len.

At $50 an hour shop rate it gets expensive real quick. For one thing, you are not putting 8 shims on the grinder and grinding them at once since they are all different sizes. You are grinding them one at a time - very expensive! Not to mention that the only way to grind them is to wet grind them which requires cleaning everything off meticulously between parts because if you dry grind them you ARE going to change the hardness of them as DINORACER mentioned.

So to answer BillB, it is not a good idea to have the shims ground.

 

Good points and research... I feel like Im riding on borrowed time every time I cruise the 1/4 mile down to the store. LOL. Stereomind gave me some valuable tips to go along with the correct process which will ensure I wont have much down time.

 

Bill, this isn't difficult. You just need to keep your wits about you.

A couple of things I probably should have included in my article:

-stuff a couple of shop rags in the camchain gallery so if you do happen to drop or fumble a shim it doesn't end up down in the motor.

-Use a "pure" metric or "primarily metric" feeler gauge, instead of an American-sized gauge with oddball metric equivalents. The math can trip you up. Recommended: KD Tools' #2274, available nearly everywhere.

-BRIGHT lighting, a fresh cup of coffee, and relax. Loosen the spark plugs to make turning the motor over easier; and be careful when turning the motor over you don't crash into the igniton pickups with your wrench.

-for the few times in the sequence where you HAVE TO turn the motor "backwards" do it slowly.

Everything else should be covered in the how-to.

Oh, and not to re-open a can of dead horses, I don't re-use shims; I replace them with new. Do a forum search to read the debate, we won't do it here.

 

Interesting. I was always told to just swap shims out. Sometimes you can use a shim you took out in a different bucket. Looks like I'll be buying new now. Only 7 or 8 dollars around here at various small shops.

 

I didnt want to say that it was do-able.. just possible. I did say to have the GROUND side down on the buckets.. Just need to add thatat the time I did this, I was a racer on a budget and with very limited time... There were times that I would surface grind the shims and then have the ground side DOWN in the bucket. The side facing the cam was always the original factory side.. As to finding a shop... Well I am a machinist and at the time I had a surface grinder at the ready for me, but then again this was before the times of the internet gained favor vs local shops. (insert favorite parts supplier) and was from 1993 to 1997 when I retired from racing.Ever hear of a rich racer... LOL me niether I never had a shim spit while out in track duty. That can be taken as track days, practice or a racing...


Sean

 

Id like to see what a worn out shim looks like.

I wonder how much wear on a shim would actually affect the performance.

 

It's not a case of "affecting the performance." If they wear enough to be out-of-spec, dimension wise, then they get discarded.

The debate is over re-using apparently "un-worn" shims.

Do a forum search on "reusing shims" we've beat this to death a few times. I won't re-use them; some folks swear by it.

 

I won't shave them.
But, I'll reuse them.

The Shim is Harder than the Valve and Cam Lobe.
It's a Shim.
It didn't swell to make the tolerance tight.
There's nothing wrong with it.

Other Forums have a "Shim Pool"
You can easily Measure the Shim to see if it's out.
I never found one that was.

You're better-off using a Used Shim of the proper size than Milling one to fit.

You should know the size of each Shim you have installed on the Head.
In some cases; moving Shims around fills the bill; without needing an Odd Numbered one.

 

I have to agree with dinoracer, Ive surface ground shims down to size, including taking up to .1mm off (which would easily have been through any surface hardening on it) and refitted ground side down and have NEVER had any issues, and after 20k miles, checking every 4k to make sure there has been NO wear on the ground ones at all (checked using a calibrated and certified toolmaker accurate micrometer, accurate to easily 0.01mm).

Im not going to disagree with anyone on here about hardening, whether or not you should reuse etc, but I can categorically state that grinding has had no effect on the wear of my shims after 20k miles of abuse (and trust me I ride hard)


Cheers
John

 

For what ever it adds to this conversation, I checked my valve clearances for the first time at 13,000 miles. The worst any of them was out of tolerance was about .03 mm or .0015". That's not bad. I probably could have gone another 13,000 miles before it started to really affect performance.

After all, we know that the biggest changes happen at break in. That's why I think that many of the guys on this forum get their bikes with right around 25,000 miles on them and they're still running and they have probably never had their valve clearances checked.

Now please don't get me wrong, I am not advocating for not following the prescribed maitenance schedule. I am simply saying to not worry so much about it. Make the adjustments on schedule and ride your motorcycle rather than worrying about it going out of spec if you ride it too much or too hard.

Who is it on the forum that has the signature "ride it like you stole it"? I like that motto. I just turned 53 and I still ride pretty hard and I still know how to have fun.

If we break our bikes we have guys like Rick and Fitz and Robert and TtR to turn to. This is awesome!

Best wishes and Happy Easter!

 

John - no lab analysis beats field testing! If you have ground .1mm off your shims with no appreciable wear then that solidifies my suspicion that even if we wear through the nitriding we don't have that much to worry about since they are through hardened prior to nitriding.

But .1mm would definitely be through the nitriding of the shims I have tested. I personally would not recommend that. But if you say that you have not had any measurable wear on them after 20,000 miles then who can argue with your results?

 

Valve clearance doesn't have anything to do with wearing the shims down; the valves pound into the head, tightening the clearances. If we were waiting for the shims and cams to wear, we'd never have to check the valves. It isn't about shim wear.

This discussion started over the possibilities of "shaving" shims to save some money on valve adjustments.

The thing about not re-using shims has to do with them "bedding in" to their particular cam lobe over time; not wearing out, or even wearing enough to affect anything. But the lobes are slightly angled so the shims rotate on the bucket and with the bucket, and they do wear in a little with their cam lobe. I don't trust then moving them to a new cam lobe with which they may or may not be all that happy. I wouldn't want to see the result if one tries to run away from its new home at 10K rpm. And mine do see 10K with great regularity.

(I'm even older than you and I ride my 550s like they were meant to be ridden; like a 2-stroke. NOT revving the living snot out of them would be abuse.)

 

Fitz - I always love your posts! Not just a man of conviction (which is rare) but a man of passionate conviction! If I add anything to these discussions it doesn't come close to what you have to say!

 

Hey I just call it like I see it; and I'm always open to new ideas. But for me, whose XJs regularly see redline, I consider $8 for a new shim cheap insurance.

I happily loan out (and even give away) used shims; they come in handy for somebody with a dead tight valve to swap in and figure out where he's at. But I won't run them in my motors, that's all. Everyone else can go right ahead.

 

I'll say that of all the shims I've swapped out, I've only found one that was worn, it it was by 0.002". Not too much but enough that it wasn't EXACTLY the size that was etched on it. I've swapped shims around for years without issue but I also don't redline my engines (sorry Fitz, I'm a chicken). But I will agree with the concept that if in doubt, get a new one.
And Fitz is a great contributor to our fair community, I enjoy and respect his opinion.

 

But but but once they're all tuned up and happy and making tan plugs and clean oil and everything these motors LIKE to be revved. I live out in the stixxx so I can go ahead and wring out the 550, and run it to 9K or redline in second, third, redline in fourth is illegal anywhere (and still got 2 gears left!) they absolutely jump right up there since that's where peak power is.

They painted the '81 Seca 550 like they did to remind everyone of the recently-retired RD400 Daytona.

And thanks for the compliment. I try.

 

10000 rpm, Fitz, is that in first gear ?
Shims, don't shave but swap.
Don't leave your bike 13000 miles between services.

 

Fitz, why are your shims half price?

 

Not first gear. I learned quite by surprise that it's not really a good idea to grab a fistful of throttle in first gear, the bike tends to want to stand on its rear wheel. Not a gentle wheelie, more like go straight up.

I generally only run first to around 7 or 8; then if it's open road ahead it's hammer time. The 550s gain revs like a 2-stroke, 10K is the redline and peak HP.

From the XJ4Ever catalog:

Aftermarket VALVE SHIMS:

Available in all sizes 2.00 thru 3.10, these are correct 29mm diameter shims with 90-degree squared edges, and are NOT Suzuki shims. Fits all Yamaha XJ models EXCEPT XJ700-X or XJ750-X engines. Select from the part number below. $7.50 each

 

Ok, I was looking at the factory original shims on UP the page.
Thanks,