valve shim measurements

[CUBuffs]

I ordered some shims from http://www.crc2onlinecatalog.com/valve_shims.htm
and think the sizes they sent are incorrect. After I installed the new shims my clearances went sky high. So I set the shims back the way they originally were and checked the clearances again---it measured out the same as before installing the new shims. So I decided to recheck my math and even used the Excel spreadsheet that is available on the forum---the spreadsheet shows that I ordered the correct shims however after installing them I get clearances from .330 to over .400.

I have a micrometer (based on inches) and can check the thicknesses of the new shims if someone can tell me what a 220, 230, & 250 shim should measure on a micrometer?

[CUBuffs]

Found conversion calculator

OK, I found a conversion calculator and the new shims check out alright (I believe). I can't figure this out.

For example measuring with feeler gauges:
#1 intake measured .127mm with a 265 shim originally
replaced the 265 with a 220 and my new clearance was now .356mm

#2 exhaust measured .152mm with a 300 shim originally,
replaced the 300 with a 230 shim and new clearance was .356mm

What's going on?

[DiverRay]

You have the decimal place wrong on the shims.
On the Exhaust, with a .152 and 300 shim, I would have gone to a 290 or 295 shim.
Look at it this way:
.152 measurement
.300 shim
+ .050 for the 295 shim
----------
.202 clearance.
I made the same mistake the first time I did this type of valve, and did it again years later when I got daily ride. I'm not a Guru yet, so I can still admit my mistakes..
Ray

[skids]

Re: Found conversion calculator

The clearance for the intake shim started out as perfect. They should measure 0.11 to o.15mm. Put the original shim back in it!

The exhaust shim should have a gap above it about .23mm. If you had .152 and you had a 300 shim (3.00mm), then (.230-.152)=.078mm. So, you need need to pick either .05 or .10mm as an increase in the gap size.

Lets look at .05: 2.95mm shim will leave about .202mm clearance.

Lets look at .10mm: 2.90mm shim will leave about .252mm clearance.

The book (Clymers pg 44) says the clearance for the ehaust valve is .21 to .24 and since NORMAL wear drifts towards excessive clearace, go with the 2.95mm shim.

Originally posted by CUBuffs

For example measuring with feeler gauges:
#1 intake measured .127mm with a 265 shim originally
replaced the 265 with a 220 and my new clearance was now .356mm

#2 exhaust measured .152mm with a 300 shim originally,
replaced the 300 with a 230 shim and new clearance was .356mm

What's going on?

[Just In Case]

Hi CUBuffs

I haven't done valve adjustments yet, so I could be wrong, but looking in my XS1100E manual, if you have measured 0.11mm to 0.15mm clearance for #1 intake, with a 265 pad, the correct pad should be a 260.

For #2 exhaust it should be a 290 or 295 pad.

To check your conversion, I work out a 250 pad should be 0.0984 inch.

David

[skids]

Re: Re: Found conversion calculator

One more thing. Check the supplement at the end of the book for newer model changes.

[CUBuffs]

Hey Everyone, thanks for your input. I was just having a conversation with my freshman college boy who explained the errors of my math ways. It matches up with what you guys explained. Thanks again for clearing that up.

[CUBuffs]

Ok, while I'm still thinking about this----just how much of a difference does it really make to the performance of the engine to add or drop to the next size shim?

[prometheus578]

"Metric... Bah!"

Madness... .
"Youse guys are gonna metric yerselfs to deeth!"
Use the American Standard numbers on the feeler gauge like God intended you to do.
On his '80 machine, the intake clearance should be .004-.006, and the exhaust should be .008 to .010.
Shims are 'metrical', numbered such like 2.25mm, 2.30mm, 2.35mm, etc. The difference in the thickness' of a 2.25 and a 2.30 shim is .05
Here comes the easy part: .05mm = .002 inches(give or take)
So, by going up or down ONE shim size, you change the clearance by .002 inches.
'zample: intake is supposed to be .004-.006 and present clearance is .002. Changing one shim size smaller will give you .004. If your clearance was .003, one shim size will give you .005.(Two shim sizes would give .007,.. too much)
There's also the variable of how the feeler gauge fits, which one can't do anything about. Does it fit tightly, have a little drag(perfect), or slightly loose, but the next size doesn't fit.

just how much of a difference does it really make to the performance of the engine to add or drop to the next size shim?

makes a difference, especially if you have too little clearance.
Valve clearances are easy to figure out. Just 'member that one difference in shim size equals .002 inches. Adjust accordingly.

[trbig]

Sure.... 6 months ago when I was doing this, Pro had no easy way to tell me about. He makes Guru... and all the sudden shortcuts come out of mid-air to him.... sigh. Had to look all over town for these Japanese feeler gauges that had one small enough!

I think (That usually gets me in trouble) that you should err on the loose side. Too tight a clearance, and you start burning valves or seats because it's not closing completely.... all these metal parts swell when they get hot. Kinda like Pro's "Guru" head!?! lol. He seems to be doing ok though... hasn't started ordering us lowly peasants around yet........ YET!


Tod

[Ken Talbot]

Aw, c'mon there, Prom, metric's not all that hard. Heck, just by talking in decimals, you're half way there. If you were talking about 1/64th of an inch I'd get a bit worried.

[prometheus578]

"I'm not a mechanic, but I play one on TV."

When I first started playing this game, I always used the 'shim conversion chart" in the manuals. (Read the clearance on the left side, then find the column on the top and ...)
Then there's the "Actual measured clearance minus the specified clearance equals the excess clearance... existing pad number add the excess clearance equals the new pad number", etc
All this math, decimal points and "metrical" stuff should have been easy for me. I mean... I learned this stuff in eighth grade. You'd figure after repeating eighth grade three times, it would have sunk in, but it didn't!
So there I was... using standard feeler gauges(.004-.008) and then converting everything to "metrical" to do the "story problem", putting in new shims and then rechecking the clearance back using standard.
"That's odd... every time I change a shim size... the clearance changes by .002." If the clearance is .002 and I drop a size, I get .004. And if there's no clearance at all... I can drop two sizes and get .004.

all these metal parts swell when they get hot

which is why the exhaust valves have the greater clearance... they heat and expand more than the intakes do due to 'the passing of the gases", which is another subject near and dear to my heart. (Do due/ Doo doo... how my feeble mind wanders...)

I think... that you should err on the loose side

I tend to agree... as I'm an agreeable sort, and an all around nice chap.