Whats the x on shim mean?

[Charlie G]

What does the x of my shim mean? I have one marked 2.60x.

Thanks for the help! Hope this is the right place for this question.


Charlie G

 

[tkent02]

It's just a little bigger than 2.60, maybe 2.62 or 2.63 or something in that range.

 

[49er]

It's just a little bigger than 2.60, maybe 2.62 or 2.63 or something in that range.

That's correct.

However, you should measure all your shims with a vernier or mic. I have found a couple that have been incorrectly marked. Also, some tuners grind metal off their shims leaving you with ????????

 

[tkent02]

Some of my shims measure quite a bit different at different spots, maybe anywhere from 2.59 to 2.63 or so, depending on where on the shim I measure.
Are new ones this sloppy or are these old and worn out?

 

[1_v8_merc]

Yep, anything with X, means it's a little bigger than the marked size, but not quite big enough to be rounded off to the next 5 or whatever.

I would NEVER re-use any shims marked with an X, unless That particular shim clearance already measured at least 0.03 or a little bigger.
Because you really don't know what it is, until you measure it!

I'm not sure if I would re-use a shim that's giving different readings on different spots of the surface? I would imagine 0.01 difference or so would be okay, because that's within the margin of error/accuracy of most Micrometers.
I'm not expert on these things, but I did get the occasional spots on shims where I would get a small Fluctuation, like 2.63, then 2.65,etc....


-----
If money is tight, you can go to Autozone and get your self a cheapy Micrometer, they have them for $30. Expect the battery to be dead when you buy it, because for some reason, when the battery is inserted, any movement turns the unit On, and it only takes a small watch battery,lol.
BUT it comes with a spare battery, so it's all good!
I have one, they work great.

NOTE: Make sure you always ZERO your micrometer first before use!
I was all excited to measure stuff, and forgot about the Zero button,lol.
All you do is just push the measuring noses together/closed, then press Zero....ready to go.
And make sure you turn the Unlock knob on the backside too! haha.

--------

Do you need any shims?
I have a couple of them lying around.....I have no use for 'em.

I know I got a couple 2.65's i believe.

 

[Charlie G]

Thanks all for the information. I kinda of figured that it X was a plus size/ It's on my list to get a better michronmeter. The one I have only reads to 1/10 of an inch, which is fine for carpentry and such. I have plenty of shims in the 2.60 & 2.65 range. Thanks for the offer! Only need to order one ( I hope). I 'm adjusting the valves on the 450. I haven't done it in the 2500 miles I've had it and boy were they tight. My smallest gauge wouldn't fit (.038mm) on three valves. I'm hoping that one size smaller will do the trick. If not will order them again. Wish I had a kit. Thanks again.

Charlie G

 

[DPage]

Charlie G, those X shims are actually very useful, and many people would like to have them, because they only came with brand new motorcycles. Here's how to use them. Say you've measured .03MM on a valve, which is the absolute thin limit on the clearance before you risk burning out your valves, and your current shim is 2.60 MM. If you have a 2.60X MM as one of your spare shims, you can put the slightly thicker 2.60X in and give yourself a little more time before you have to measure the clearance again. I have 3 of these X shims and will never get rid of them. Use those X shims in good health!

Later Edit: The example above is incorrect. As Steve says below, installing a thicker shim will actually decrease clearance, and if you're already at the thin limit of .03 MM that would be a very bad idea. Sorry! X shims work in the other direction - if you're at .08 MM, use an x shim to get you something like .06 MM

 

[Charlie G]

I don't trow anything away, at lest if that small. I think I remember someone looking for an X shim in one post. I have a friend around the corner who has a whole machine shop. He offered to put my shims on his surface grinder and make them whatever I wanted. I want to preserve the ones I have. I have a lead on a GS1000g and ya never know what your going to need. By the way..If you want to increase the clearence you put in a smaller shim, right?

cg

 

[DPage]

By the way..If you want to increase the clearence you put in a smaller shim, right?

cg[/QUOTE]

I'd say THINNER shim, but right.

 

[Steve]

Here's how to use them. Say you've measured .03MM on a valve, which is the absolute thin limit on the clearance before you risk burning out your valves, and your current shim is 2.60 MM. If you have a 2.60X MM as one of your spare shims, you can put the slightly thicker 2.60X in and give yourself a little more time before you have to measure the clearance again.

Not quite right, there. :-k

If your clearance is already at the minimum, installing a thicker shim will reduce it even more.

If you had minimum clearance with a 2.65, you could put in the 2.60x, but why? If you went with a 2.60, you would be at the maximum, which will make it even longer before you need to change it again, and your street engine will actually run better with larger clearances.

.

 

[Charlie G]

Not quite right, there. :-k

If your clearance is already at the minimum, installing a thicker shim will reduce it even more.

If you had minimum clearance with a 2.65, you could put in the 2.60x, but why? If you went with a 2.60, you would be at the maximum, which will make it even longer before you need to change it again, and your street engine will actually run better with larger clearances.

.

Thanks Steve! I had it straight in my head.

cg

 

[gswisconsin]

I am also working on my clearances for my 1982 gs450gaz. I believe the clearance spec is .001 to .003 in or .03mm to .08mm. My question is - would it be a good idea go to .004 in. (0.10mm)?
I also have been checking the clearance with piston at TDC with lobes at 90 degrees to valve stem for both intake and exhaust. Is this correct? By the way all of my shims have the X mark as well. All my valves are tight except one. I am using a .0015 in (0.04mm) feeler and it is a no go except for my one intake. This is the smallest feeler I can find.
This bike was neglected. Mileage is 45k. So if I have x shims they are original factory shims and therefore may explain why I have 35psi compression on one cyl. If I do have a valve not seating I was thinking that the extra clearance might not hurt a bit if the valve in not seating properly and needs to work itself to its seat again. Am I on the right track?

 

[tkent02]

I am also working on my clearances for my 1982 gs450gaz. I believe the clearance spec is .001 to .003 in or .03mm to .08mm. My question is - would it be a good idea go to .004 in. (0.10mm)?
I also have been checking the clearance with piston at TDC with lobes at 90 degrees to valve stem for both intake and exhaust. Is this correct? By the way all of my shims have the X mark as well. All my valves are tight except one. I am using a .0015 in (0.04mm) feeler and it is a no go except for my one intake. This is the smallest feeler I can find.
This bike was neglected. Mileage is 45k. So if I have x shims they are original factory shims and therefore may explain why I have 35psi compression on one cyl. If I do have a valve not seating I was thinking that the extra clearance might not hurt a bit if the valve in not seating properly and needs to work itself to its seat again. Am I on the right track?

Checking that way will give bogus readings, use the Suzuki method from the manual.
Too tight valves will give low compression, adjust the clearance and the compression is fixed. Unless you burned a valve. A lot of guys run .10 mm with no troubles.

 

[Charlie G]

.038mm is the smallest gauge I could find. My manual shows checking the clearence with the lobes up, 90 degrees from the head surface. I was no go on three of mine and I hoping I will have enough clearence with the shims I ordered. If not I'll order again. I sure like my valve tool. Beats the heck out of the old screwdriver I ground and shaped years ago.

cg

 

[Steve]

.038mm is the smallest gauge I could find.

That tells me that you are actually using INCH feelers that have metric APPROXIMATIONS printed on them. As much as we advocate using metric measurements, since you are using INCH feelers, that is what you should report.

My manual shows checking the clearence with the lobes up, 90 degrees from the head surface.

What manual are you using? I have a factory manual, Clymer and Haynes for my 850s. All three of them show the same procedure, which places the cam lobe for IN 1 pointing FORWARD and IN 2 (assuming this is on a four-cylinder engine) pointing UP. While the cams are in this position, measure BOTH, IN 1 and IN 2. Rotate the crank 180 degrees, the cam lobe for IN 1 will be pointing UP, the lobe for IN 2 will be pointing BACK. Measure and record BOTH of them. Rotate the crank another 180 degrees, do EX 3&4. Rotate the crank a final 180 degrees, check IN 3&4.

You should note that while the cams are in the proper position, the two lobes will be at about 45 degrees to their respective valves. Neither one is touching, which might distort the cam ever so slightly, assuring consistent readings.

I was no go on three of mine and I hoping I will have enough clearence with the shims I ordered.

Your smallest shim is ever so slightly larger than the minimum clearance allowed, which means that there is a very slight chance that the clearance is still in spec. No problem, don't worry about it. Try to rotate the bucket and shim. If you can move it easily, the cam is not pressing down on it. Changing just one shim size will bring you up to about the middle of the range. Since you said you had all X shims :clap:, you will not be able to go exactly one size, so go for the extra clearance. For example, if you have 2.65x, go for a 2.60. If you had 2.60x, go for 2.55. That will put you at or just slightly more than the 0.08mm (0.003") specified, but for a street engine, that's OK.

I sure like my valve tool. Beats the heck out of the old screwdriver I ground and shaped years ago.

I'm glad somebody likes that tool. I have one in my toolbox. The only time it comes out is when I show somebody what it looks like. Then I show them how much easier the zip-tie method is, and we continue with the zip-tie.

Since you are actively in the process of doing your valves, I will invite you to read the last part of my sig and take advantage of the offer.

.

 

[Charlie G]

Thanks Steve for your input. I have a Clymers manual for my 450 twin and it just shows the one cam lobe position. When I adjusted the valves on the 650g the manual noted the two positions you wrote of, which I followed. It's nice to have someone to bounce ideas off of.

cg

 

[Steve]

Thanks Steve for your input. I have a Clymers manual for my 450 twin and it just shows the one cam lobe position.

OK, twin noted, but you had not mentioned which bike you were working on. You have several in your sig, but did not say which one.

Although we had a 450 in the garage a few years ago, I don't remember ever adjusting the valves on it, so I don't know what is called for in the way of cam position. Generally, having the lobe pointing away from the valve is good, but in the case of the fours, spreading them apart a bit will keep either one of them from pushing on a valve, assuring consistent readings.

.

 

[gswisconsin]

On the 450 twin, would it not make sense to check valve clearance for one cylinder at TDC on the compression stroke, since this is when you really want the intake and exhaust valves to both be closed to assure maximum compression? Both intake and exhaust cam lobe will be at 90 deg. from valve stem.

 

[hampshirehog]

I've never understood the need of the X shims when so many, new and old, shims are incorrectly sized anyway - eg a marked up 2.65 is actually 2.67. Measuring every shim with a caliper is essential - don't rely on the numbers.

 

[Steve]

I've never understood the need of the X shims when so many, new and old, shims are incorrectly sized anyway - eg a marked up 2.65 is actually 2.67. Measuring every shim with a caliper is essential - don't rely on the numbers.

I measure all my shims. The only time I have seen one with a different measurement than the number printed on it, it was due to measuring technique. I will wipe the shim, wipe the jaws of the caliper, check to make sure they read 0.000, then measure the shim at several points around the shim. A 2.65 shim might get measurements of 2.645, 2.65 or 2.655, depending on whether there is a speck of dust on the shim or I am squeezing a bit tighter, but they all measure 2.65.

On the other hand, a 2.65x might read 2.67 or 2.68, but there is no guarantee that the "X" means exactly half-way.

.