Valve Shims

[SthrnSqrl]

Ok, measured my valve clearances, checked the shims for size, and figured out which shims I need to replace with. BUT...I'm still not sure I did it properly, so could someone please check my work, so I don't screw up and spend another week down because of not getting the right ones? And yes, I realize that I can swap a couple of these around, and save having to replace all 8 of them.

Int Clrnc Shim Need

#1 - .140 - 255 - 235
#2 - .166 - 255 - 240
#3 - .140 - 255 - 235
#4 - .114 - 265 - 230

Exh

#1 - .203 - 280 - 265
#2 - .213 - 275 - 265
#3 - .229 - 280 - ~
#4 - .191 - 290 - 270

[prometheus578]

Man, I don't know where you got your numbers from...
Next time, much easier to use standard measurements, not metric.

OK....

INTAKE:
Clearance-------Shim---------need shim
#1--.140--------255----------- 250
#2--.166--------255-------------0-
#3--.140--------255------------250
#4--.114--------265------------260


EXHAUST:
Clearance-------Shim---------need shim
#1--.203--------280-----------275
#2--.213--------275------------0-
#3--.229--------280------------0-
#4--.191--------290-----------285

EDIT:
Thanks, LarryM....
I rechecked my numbers for the tenth time... found where I had typed an error(260 instead of 250)
Clearances usually only change by one shim size. If you find a change more than that, recheck your math to be sure.

[Larrym]

Error Prone...

Uhhh mebbe cause the morning coffee hasn't kicked in but....

No matter how I enter the data you provided into the downloadable "Valve Shim Calculator" (Courtesy of some "Hired Goon"...) available here on channel 11...


I don't come up with the same numbers you do.

Still...Let's wait and get someone else's input before I post the numbers I got, OK??

Part of that "Department of Double Redundancy Department" policy/practice.

Rat's!! Too slow on my part as Prom got outta the gate first.

My numbers don't even match what he provided. Gawd!!

I guess I better try to figure out what I did wrong...has to be user error, right???

[prometheus578]

That's the problem with using metric and the chart. Too many numbers, too many columns, too many ways to make a stupid error. I rechecked my numbers, Larrym... I, too, made an error. Wasn't even a "chart" error, either (A typo from 250 to 260)

(Had he given his data in "standard' measurements... hell, I could have done it in my head for him)



Here's an old argument for using Standard over Metric:

http://www.xs11.com/forum/showthread...highlight=.002

[Larrym]

I could w'ile away the hours....

That's a keeper, Prom. "Classic" and bookmarked on my laptop.

I'm sorta Cheating by using that "calculator" to do what my brain cells should be doing instead.

It does work, right???

(Not my brain....that's always an iffy thing. I mean the Valve shim calculator!)

[SthrnSqrl]

First of all, the reason I gave the measurements in metric, instead of standard, is because the shims are only marked in metric. My feeler guage will do either. I thought it kind of dumb to use the standard markings, when the shims were not marked that way.

The measurements you quoted will just barely get me in spec, no? The reason I used the measurements I did is that the final adjustment will put me in the middle of the accepted range. This would give me more time before the shims would have to be replaced again, right? If I just barely get them into specs, then next spring, I'd need to pull the cover and do this all over again, if I ride very much.

[bikerphil]

I prefer using the english conversion myself. If you want to convert in metric, this is for the 78-79 motors....

[prometheus578]

Well, let's see....

Many variables here.
(and some things that aren't variable... like the shims)
The numbers given will get you into the acceptable range.
That is: .16-.20mm (.006-.008) intake/ .21-.25mm (.008-.010) exhaust.

Now then... let's look at your feeler gauge readings. How did the gauge go in? Was it tight? Was it somewhat loose? Or as Goldilocks said. "This one's just right."
That's a variable you can't do anything about, so there's even some "give" concerning feeler gauge readings.
What you can't change is the sizes of the shims. Here's what I mean.

Say one of your intake valves is tight. You need to go to a thinner sized shim.
If the original clearance was .005 (.127mm), the next smaller shim will give you .007 (.178mm)...right in the middle of the acceptable range
Now, suppose you'd really like it to be .008, for as you said, this would give you more time between valve adjustments. This is true, but given the shim sizes available to work with, it's not gonna happen. Your only gonna be able to get .007 (.178mm)

We can try to be as precise as we can get, but there's only so much that you can do.

The measurements you quoted will just barely get me in spec, no?

Based upon your measurements... some of your valve clearances are too tight. The only thing that you can do is go to a smaller sized shim. This will place you within the acceptable range. Where in that range it places you... you can't do anything about.

Now, while it's true they used to make "half shim" sizes like 2.655mm or 2.805mm for people who really, really wanted to get their valves "just so"... these are rarely seen and are extremely hard to come by.

[SthrnSqrl]

Many variables here.
(and some things that aren't variable... like the shims)
The numbers given will get you into the acceptable range.
That is: .16-.20mm (.006-.008) intake/ .21-.25mm (.008-.010) exhaust.

Now then... let's look at your feeler gauge readings. How did the gauge go in? Was it tight? Was it somewhat loose? Or as Goldilocks said. "This one's just right."
That's a variable you can't do anything about, so there's even some "give" concerning feeler gauge readings.
What you can't change is the sizes of the shims. Here's what I mean.

Say one of your intake valves is tight. You need to go to a thinner sized shim.
If the original clearance was .005 (.127mm), the next smaller shim will give you .007 (.178mm)...right in the middle of the acceptable range
Now, suppose you'd really like it to be .008, for as you said, this would give you more time between valve adjustments. This is true, but given the shim sizes available to work with, it's not gonna happen. Your only gonna be able to get .007 (.178mm)

We can try to be as precise as we can get, but there's only so much that you can do.


Based upon your measurements... some of your valve clearances are too tight. The only thing that you can do is go to a smaller sized shim. This will place you within the acceptable range. Where in that range it places you... you can't do anything about.

Now, while it's true they used to make "half shim" sizes like 2.655mm or 2.805mm for people who really, really wanted to get their valves "just so"... these are rarely seen and are extremely hard to come by.

Ok, see, this is why I posted my findings before I did anything. I think I understand what you are saying, and if I do, I know exactly where I went wrong. ie, Intake valve #4-.114-265-235 in my op. With a measurement of .114, and existing shim of 2.65, I wanted to get my valve clearance to ~.18 mm. Knowing that the shims go in increments of .005mm, I took the ~.07mm difference and multiplied it by 5(Don't ask...I haven't a clue how I came up with that.) This adjustment (in theory) gave me clearance of .184mm...right in the middle of acceptable range.

While I still don't fully understand the findings ( I am a very visual person), I yield to your experience in the matter.

My measurements were all measured the same way...tight, but would go...like when I set my spark gap. There was drag on the feelers, but not enough that I had to displace the valve to get it in there.