Metric calculations or someone good with shims?

I've been checking valve clearances and I have assorted sizes of shims but none small enough to get within spec. I have a 250 shim (2.50mm) and am able to get my .014 feeler gauge "in".
My question is... If I dropped a 245 shim (2.45mm) "in" wouldn't that give me a .019 clearance? Spec on Exhaust is .016~.020
Something I just noticed on the valve clearance chart at http://xjbikes.com/Forums/viewtopic/t=14827.html
it states the clearance at 0.16~0.20. Is this a typo or are my clearances way off? Been awhile since I've been in school but .016 and 0.16 isn't the same is it?
Thanks

 

Correct exhaust clearance on airheads is .16-.20mm yes, I don't know what .014" is in metric though but a 245 wouldn't take it to .019" no because the shims are sized in metric (that's why we measure our valves in metric lol!) & the difference between 250 & 245 is .05mm.

EDIT-: hang on, you're saying your clearance is .014mm? Yes that's way small, like nearly nothing... Are you using proper metric feelers?

 

.014 what? Inches? That would be .35mm, which is wayyy loose.

The "inch" equivalents of the valve clearances are as follows:

Intake .004" ~ .006" (approx. .11mm ~ .15mm)

Exhaust .006" ~ .008" (approx. .16mm ~ .20mm)

Shims are sized in .05MM (.00197") increments; you can't use the .05 with "inch" calculations.

If it's a .14mm feeler, then yes, you'd use one size smaller shim to accomplish a .19mm clearance. If it's an exhaust valve measuring .014MM, then you'll need three sizes smaller to get to .16mm.

 

Okay well now I've just confused myself! I have the famous K-D angled feeler gauge. Has 2 sizes on each feeler. Example: .016 over .406 so I'm trying to get 0.16~0.20mm.
My smallest feeler is .008 over .203 So that is the feeler I should be aiming for?

 

Smallest feeler is .003mm too big to get you in maximum-gap spec, you really need some metric gauges...

Will be so much easier when you're working to proper metric sizes, Fitz knows the KD part number

 

Okay I got what y'all are saying now. 750E-II_29Rbloke you threw me at 1st with your .003mm too big comment. But yes it would be .203 - .20 = .003 too big.
I love the USA but we never did embrace that metric idea. *lol*
I shall get a set of Metric gauges that go smaller. At least down to .10mm since I'll need .11~.15mm for Intake spec.
Thanks

 

yep you got it it's no fun converting when sometimes the only difference in the numbers is the position of the decimal point.

Even though .003mm is a fag-paper tiny difference all the old hands will tell you "in spec is in, out is out", and you're right you'll be able to do all your inlets with the metric set as well.

Biggest bonus is how simple it will be to know what shims you need...

Nothing wrong with Imperial (I would say that, we invented it lol) but metric's slowly taking over the world :?

 

I know there are very simple tools and guides on line or at most any hardwhere store in the U.S.A. that have metric to standard conversion guide or look it up on line. I have three or four books on this laying around so if you get in a pinch pm me ill convert it for you but like I said online there is a bunch.

 

The feeler gauge in question is the K-D Tools #2274.

.003 of a MILLIMETER is small enough to just drop it. That's .00012" feeler gauges don't even come that thin. A human HAIR is at least .0006" fer chrissakes.

 

Yeah that's sorta what I though too bigfitz52 about the .003. I'll still need smaller ones though for the Intakes so I'll just give into my OCD and get the new set of gauges that go smaller. Are the K-D Tools #2274 bent (angled)?
I found a K-D Tools Go-No-Go Feeler Gauge #2424 that looks good.

 

All feeler gauges show the thickness/measurment for metric readings in a NOMINAL (meaning "actual") size, i.e. .406 or .203 is the ACTUAL metric measurement (and which can be compared directly to the .11-.15mm or .16 - .20mm valve clearance specifications).

Imperial/SAE/USA/whatever-you-want-to-call-it are FRACTIONAL sizes, i.e. they specify a PERCENTAGE of a base NOMINAL size (in this case, of a base nominal size known as an "inch")..........BUT, since a percentage is a percentage is a percentage (no matter what the base nominal size under discussion is) then it's a simple matter to use a percentage size to calculate the nominal size for any unit.......including metric measurements.

25.4..............that's the number to keep in mind.......memorize....tattoo on your wherever, as that is the how many millimeters are in an inch.

So for an Imperial/SAE/USA percentage size of, say .008 (= 8 thousandth's, or 8/1000 of a base unit, or .008 of an INCH --- which is written as .008".....note the " symbol at the end of the numbers, that specifies the BASE UNITS and " refers to inches, just as mm refers to millimeters), then .008 x 25.4mm = .2032mm

Here's a couple of more examples:

.010 x 25.4mm = .2540mm
.003 x 25.4mm = .0762mm
.005 x 25.4mm = .1270mm

The "shim charts" in Yamaha/Haynes/etc. manuals are confusing because, in someone's great quest for being consice, THEY LEFT OFF THE UNITS OF MEASUREMENT in the "measured clearance" column, i.e. they have measurements listed as:

0.06 - 0.10
0.11 - 0.15
0.16 - 0.20
etc.

This is quite confusing to people who are not used to looking at NOMINAL sizes (people in the USA are thinking in terms of PERCETAGE sizes, i.e. 8 thousandths of an inch or 8/1000 or .008%), and just because the base unit is a "1" they don't realize that they are referring to a percentage, since 8 thousandths of ONE INCH (the base unit), or 8/1000 of ONE inch, or .008% of ONE inch results in the same NOMINAL (actual) measurement (since the base unit of measurement is ONE), thus

.008% x 1 = .008 OF A 1-INCH BASE UNIT = .008" actual clearance
8/1000 x 1 = .008 OF A 1-INCH BASE UNIT = .008" actual clearance

The " at the end of the measurement (.008") is really specifying the unit of measurement.........for clarity and consistency, it should read .008inch, just like metric readings are written as .008mm.........but that's a whole 'nother discussion.


But when going to a BASE UNIT of 25.4 (millimeters), then we have:

.008% x 25.4 = .008 OF A 25.4 BASE UNIT = .2032mm actual clearance
8/1000 x 25.4 = .008 OF A 25.4 BASE UNIT = .2032mm actual clearance

I understand that the above explanation will seem CONFUSING, at first, to many people, but, in reality, it is what's actually "going on" in the books and "in the math". Once you grasp the difference you'll be able to do the metric-to-SAE calculations easier (and correctly).

We also offer a nice METRIC feeler gauge set that is marked in both metric and SAE sizes..........the main differences between METRIC and SAE feeler gauges sets is how thick the blades are:

- in SAE sets, the blades are sized in a logical PERCENTAGE size format, i.e.:

.001% = 1/1000 of a BASE UNIT = 1/1000 of an INCH = .001" = 1/1000 of 25.4 MM = .0254mm

.002% = 2/1000 of a BASE UNIT = 2/1000 of an INCH = .002" = 2/1000 of 25.4 MM = .0508mm

.003% = 3/1000 of a BASE UNIT = 3/1000 of an INCH = .003" = 3/1000 of 25.4 MM = .0762mm

Note that the SAE measurements are in nice "equal" increments of sizes:
.001", .002", .003", etc.

While the millimeter measurements are "odd" size increments:
(.0254mm, .0508mm, .0762mm, etc.)


METRIC feeler gauges have blade sizes that are nice even increments in metric sizes:

.01mm, .02mm, .03mm, .04mm, .005mm, etc.

which is very useful when dealing with specifications that are given in (un-referenced in the shim charts) metric units, such as valve clearance specs.

Note that the METRIC feeler gauges end up with "odd" imperial sizes:

.01mm = .01/25.4 = .0003937 of an inch
.02mm = .02/25.4 = .0007874 of an inch
>>> here is where a SAE reading of .001 would be (.0254mm)
.03mm = .03/25.4 = .0011811 of an inch
.04mm = .04/25.4 = .0015748 of an inch
.05mm = .05/25.4 = .0019685 of an inch
>>> here is where a SAE reading of .002 would be (.0508mm)
.06mm = .06/25.4 = .0023622 of an inch
etc.


Hope this helps..........


P.S. for the water-cooled X-engines, these are the feeler gauges that we offer:

HCP6383 Aftermarket METRIC FEELER GAUGES SET. These gauges will work on all XJ engines including the XJ700-X and XJ750-X water-cooled models, which require narrower blade-tip feeler gauges to check the intake valve clearances on those models. Aftermarket 32-blade metric set has 95mm long blades, hardened and polished, with the thin, tapered ends needed to access the valves on these models. Marked in both metric and decimal equivalents, as listed below. NOTE: these feeler gauges will fit perfectly, although you will have to rotate the blade 90 degrees to the holder for some of the inner valves on X-models. Each:

Comment: the inclusion of inch measurements AND the inclusion of smaller sizes makes this set ideal for all XJ-bikes and especially for X-models.