Help with valve shims

I'm hoping someone can help me. I only have a standard feeler gauge set (not Metric). Here are my measure ments

Intake
.003 004 .004 .004
285 280 285 280

Exhaust

.005 .006 .003 .003
275 275 280 280


I am hoping that someone can tell me which shims I should order for each above. Thanks.

 

Translating to metric:

INTAKE CLEARANCES SHOULD BE: .11 - .15mm

Intake #1: .003" with a 285 shim currently installed =
.0762mm clearance

* you need a minimum of .110 - .0762mm additional clearance =
.0338mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.85mm shim - .05 =
2.80mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .0762mm to .1262mm, assuming that your currrently installed 285 shim IS actually 2.85mm thick! (it may not be!!)



Intake #2: .004" with a 280 shim currently installed =
.1016mm clearance

* you need a minimum of .110 - .1016mm additional clearance =
.0084mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.80mm shim - .05 =
2.75mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .1016mm to .1516mm, assuming that your currrently installed 280 shim IS actually 2.80mm thick! (it may not be!!)

* although the .1516mm clearance is outside of the specified range, in this case it would be preferrable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.



Intake #3: .004" with a 285 shim currently installed =
.1016mm clearance

* you need a minimum of .110 - .1016mm additional clearance =
.0084mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.85mm shim - .05 =
2.80mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .1016mm to .1516mm, assuming that your currrently installed 285 shim IS actually 2.85mm thick! (it may not be!!)

* although the .1516mm clearance is outside of the specified range, in this case it would be preferrable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.



Intake #4: .004" with a 280 shim currently installed =
.1016mm clearance

* you need a minimum of .110 - .1016mm additional clearance =
.0084mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.80mm shim - .05 =
2.75mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .1016mm to .1516mm, assuming that your currrently installed 280 shim IS actually 2.80mm thick! (it may not be!!)

* although the .1516mm clearance is outside of the specified range, in this case it would be preferrable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.

*************************

EXHAUST CLEARANCES SHOULD BE: .16 - .20mm

Exhaust #1: .005" with a 275 shim currently installed =
.1271mm clearance

* you need a minimum of .160 - .1271mm additional clearance =
.0329mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.75mm shim - .05 =
2.70mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .1271mm to .1771mm, assuming that your currrently installed 275 shim IS actually 2.75mm thick! (it may not be!!)




Exhaust #2: .006" with a 275 shim currently installed =
.1525mm clearance

* you need a minimum of .160 - .1525mm additional clearance =
.0075mm additional clearance.

*since shims are only available in .05mm increments, you need a
.05mm THINNER shim to get MORE clearance.

* current 2.75mm shim - .05 =
2.70mm shim needed.

* this .05mm thinner shim will increase your clearance from the current .1525mm to .2025mm, assuming that your currrently installed 275 shim IS actually 2.75mm thick! (it may not be!!)

* although the .2025mm clearance is outside of the specified range, in this case it would be preferrable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.



Exhaust #3: .003" with a 280 shim currently installed =
.0762mm clearance

* you need a minimum of .160 - .0762mm additional clearance =
.0838mm additional clearance.

*since shims are only available in .05mm increments, you need a
.10mm THINNER shim to get MORE clearance.

* current 2.80mm shim - .10 =
2.70mm shim needed.

* this .10mm thinner shim will increase your clearance from the current .0762mm to .1762mm, assuming that your currrently installed 280 shim IS actually 2.80mm thick! (it may not be!!)



Exhaust #4: .003" with a 280 shim currently installed =
.0762mm clearance

* you need a minimum of .160 - .0762mm additional clearance =
.0838mm additional clearance.

*since shims are only available in .05mm increments, you need a
.10mm THINNER shim to get MORE clearance.

* current 2.80mm shim - .10 =
2.70mm shim needed.

* this .10mm thinner shim will increase your clearance from the current .0762mm to .1762mm, assuming that your currrently installed 280 shim IS actually 2.80mm thick! (it may not be!!)

 

Uhhh......what he said ;-P

 

Thanks Len,
Will put my order togeather in the morning.

Keith

 

Wow Chacal !!!

I'm not registrated since long time but what a great explanation .

 

Len, I do have a question (not to hijack thread) you state that clearances shrink after time.

I always thought they increase (due to wear and tear)...? Why would they/do they shrink (carbon build up or something?)?

thanks!

 

Geez Len, wouldn't it have been easier to just post the chart?

 

Clearances tighten because over time the valve sits "further into" it's seat thus bringing the top of the valve stem closer to the camshaft lobe (via the bucket.

 

Ahhh, ok. That makes sense.

 

Precisely. Over time the valves pound themselves deeper into the seat. On motors with rocker actuated valves, the wear in the valve train IS greater than the "pounding into the head" factor, so they do loosen up.

Also note the adjustment interval is a lot greater on the bucket-over-shim XJ motor than rocker-valve motors. I check/set the rocker clearances on the Norton every 2500 miles MAX.

 

I actually hate the shim chart, it's one of the most confusing darned things that I've ever come across!

In an effort to be "compact and efficient", they've presented the information in such a manner that is both difficult for an inexperienced person to:

a) read
b) interpret correctly
c) thus select the proper shim from.

In essence, it's a "mistake waiting to happen".


I also don't like that the left hand column (clearance measured) is not noted as to the units (mm), and since people tend to measure things in fractional units sometimes, I can't ever recall which way the shim chart is labeled (it is metric); either way, it's just horrible presentation error to not label units of measurement when it is known (or could/should be assumed) that users have two different measurement units available to them, and will sometimes use one, and at other times a different one.


But wait, there's more! If you look at them right now (operators are standing by....) we'll also make sure that the clearances specified on the shim chart in both the Yamaha and the Haynes manual for the "Exhaust" chart are incorrect...........

And if you order in the next 20 minutes, we'll also throw in a FREE! Haynes chart which illustrates a separate, unique intake chart for the XJ650 (UK) and XJ650J models, which is also incorrect.....


Other than that, the shim charts are Great!


But in any case, my preference is to understand the actual mechanics of what is going on, and the above example is how it is done (in proper logical order). If you want your own "cheat sheet", well, here it is:

*********************************************

Metric conversion table:

XXXi => XXXm

.001" = .0254mm
.002" = .0508mm
.003" = .0762mm
.004" = .1016mm
.005" = .1271mm
.006" = .1525mm
.007" = .1779mm
.008" = .2033mm



Translating to metric:


INTAKE CLEARANCES SHOULD BE: .11 - .15mm (all except "X" engines)

Intake #?: .XXXi" clearance with a YYYa shim currently installed =
XXXm .mm clearance

* you need a minimum of .110 - .XXXm mm additional clearance =
.ZZZ mm additional clearance.

*since shims are only available in .05mm increments, you need a
.AAmm THINNER shim to get MORE clearance.

* current YYYa mm shim - .AA =
YYYb mm shim needed.

* this .AAmm thinner shim will increase your clearance from the current .XXXm mm to .MMM mm, assuming that your currently installed YYYa shim IS actually YYYa mm thick! (it may not be!!)


optional, if you run into an overlap situation:

* although the .MMM mm clearance is outside of the specified range, in this case it would be preferable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.



*************************

EXHAUST CLEARANCES SHOULD BE: .16 - .20mm (all except "X" engines or XJ1100....1100 engines use .21 - .25mm exhaust clearance)

Exhaust #1: .XXXi" clearance with a YYYa shim currently installed =
XXXm .mm clearance

* you need a minimum of .160 - .XXXm mm additional clearance =
.ZZZ mm additional clearance.

*since shims are only available in .05mm increments, you need a
.AAmm THINNER shim to get MORE clearance.

* current YYYa mm shim - .AA =
YYYb mm shim needed.

* this .AAmm thinner shim will increase your clearance from the current .XXXm mm to .MMM mm, assuming that your currently installed YYYa shim IS actually YYYa mm thick! (it may not be!!)


optional, if you run into an overlap situation:

* although the .MMM mm clearance is outside of the specified range, in this case it would be preferable to have too LARGE a clearance rather than too SMALL a clearance, which is what your current situation is. Since clearances SHRINK over time, it is better, in this situation, to have a slightly too large of a clearance rather than too small.

*****************************

Of course, in the rare situations where you need LESS clearance than is existing (gap to large), you just make the necessary adjustments to these lines of the code (this is the exhaust table):

* you need a maximum of .XXXm mm - .160 mm less clearance =
.ZZZ mm less clearance.

*since shims are only available in .05mm increments, you need a
.AAmm THICKER shim to get LESS clearance.

* current YYYa mm shim + .AA =
YYYb mm shim needed.

* this .AAmm thicker shim will decrease your clearance from the current .XXXm mm to .MMM mm, assuming that your currently installed YYYa shim IS actually YYYa mm thick! (it may not be!!)


Perhaps we have some bit-floggers out there that want to write a Q&D routine and post it somewhere (Sno, anyway it could be on a sidebar somewhere?) so that the mental gymnastics could be kept to a minimum for the numerically-challenged amongst us.........

 

Hmmm.. Should be able to do that up in an excel spreadsheet so it does all the math for you pretty quick and easy. Can set it so you just input your measurements - specify if its mm or metric and then have it do its magic.

Might have to play with that, will post when I can. If I can't figure out, I have a MS Excel wizard at my office that owes me a favor ;-)

(I know its a simple thing to do manually with your write-up, but I am lazy ;-P and having something where I just type in the numbers and it does all the work so I couldn't possible mess it up.. I'm all in ;-) ).

--josh

 

Swell....but you might want to check with SnoSherrif first to see what type of code is compatible with this site.......

 

Worst case scenario I can put it into a excel spreadsheet. Or I can just do up a quick webpage application on my site that does it for everyone - so it could be separate from the site in case there was any compatibility, or other, issues.

I don't want to step on anyone's toes or anything.

 

Hey Chacal, you ever considered teaching mechanical engineering. WOW, that was an indepth explanation. If I had that much math in my head, it would probably explode.

I just did a valve check/adjustment on my xj650 with the shims I ordered from you. Clearances are back within specs. I had no trouble at all reading the chart for the correct pad replacement.

Thanks Chacqal for all the help you give us on the forum.
You sir are a godsend!!

 

Thanks Corgi, although it's really quite simple:

You have a GAP that you want to be a certain SIZE ("clearance").

The only way to adjust the gap is via a removable, replacable SHIM.

If the GAP is too SMALL (typical situation), then I want to INCREASE THE GAP.

I can INCREASE THE GAP by using a THINNER SHIM. A thinner shim makes the gap WIDER.

Since shims only come in .05 increments, it's just a matter of adding or subracting by "5's"..........and I'm fairly good at that!


Of course, vice-versa if the GAP is too LARGE.............

 

.05 millimeter increments. (You were faulting the chart for not specifying units of measure.)

True, the chart is sort of confusing; it took my 9-year old a few minutes to master it when he helped me do my last valve adjustment.

I think the BIGGEST issue arises from the metric-imperial conversion issue. Most commonly-available feeler gauge sets are imperial although some do have metrics printed on the blades as well, they come out to oddball sizes. .004" is actually .1016mmm, NOT .11mm; .006" is .1524mm, not .15mm. So trying to measure the gap using imperial-sized gauges and then trying to plug the oddball results into the chart causes confusion. If you use a purely metric gauge and do everything in metric the chart works fine. (IMHO)

That being said it doesn't hurt to understand the "theory" behind it.

 

This is why it's logical for everyone to use metric... stupid imperial system and it's fractions heh

i like base10

 

We tried going metric here some years back; but it just wouldn't stick. We were SUPPOSED to have KM/H road signs and everything by now, but it never happened.

 

About how many mm will the gap increase by using the next size thinner shim?

 

Supposedly by .05mm exactly, since the shims are only available in .05mm increments. But that assumes that your original, used "270" shim (for example) is still 2.70mm thick....time and usage may have actually reduced it to 2.69mm thick, or 2.68mm thick, etc........in which case going to the next thinner shim (265) will not increase the gap by .05mm, but by some lesser amount......

Remember, with the original shims in place, you measured a GAP, and that GAP (assuming you measured it correctly) is the REAL, TRUE GAP.

The "Y270" marked on the back of your original, installed shim, MAY or MAY NOT be a REAL THICKNESS, due to wear issues.

That's why, when making your calculations for what size replacement shims you need, you either (or, really, do both) need to measure your used shims (don't accept that their marking is true) and use their actual dimension in the "formula" (which the shim chart does not account for); or, after you order and install replacement shims, rotate the engine over a few times and then re-measure the gap, to be sure.......

 

So now I've got the valves back in spec. The shim I replaced brought the clearance back to only .12mm. Spec calls for .11 - .15mm on intake. Engine is quieter, but not all valve noise has disappeared. Seems like a clearance closer to .14 or .15 would quiet it down. Some knowledgable opinion here would help.
On the exhaust side, spec is .16 - .20mm. Now if it were .19mm would it seem quieter than at say .17mm??

Bike has no hesitation indicative of a cam chain in need of adjustment. Bike has the automatic tensioner.

 

Well, spec is spec. .12mm is close to the low end of the spec, and it will probably get to that low end somewhat quickly, as the gap decreases over time.

Smaller gaps (lower numbers, but of course always within spec) would tend to make the valve train "quieter", although quiet really isn't your "goal"------have clearances that are within the specified ranges are!

 

corgitwo,

One of the confusing things about the valve train on these bikes is that because of the valve bucket and shim geometry the valves actually get TIGHTER as they wear instead of looser as with conventional valve tappets. This is confusing as heck but it's the nature of the beast.

If you are in spec then that's a good thing. You run the risk of burning valves if they wear tight enough that a valve hangs open.

Loren

 

You're not after quiet; you're after valve clearances that are within spec. Valves with tighter clearances will be quieter than they will with wider clearances; but tighter is NOT better. They need to be in spec and don't worry if it's a bit noisier that way.