'05 ST13, Cyl #1 Exhaust Valve new shim is .108?

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Sep 9, 2006
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Hello and help!

At 80k, I figured I'd better do my second check.

I had a total of six valves that needed to be fixed: both intake on #4, 1 intake and both exhaust on #1, and one exhaust on #3.

Fine.

Got the hotcam shim kit, all is good.

Intake valves are no problem. I'm able to match a hotcam replacement shim almost to the thousandth of a millimeter.

My exhaust valves, however, are another issue.

Using the formula in both the Haynes manual and Honda shop manual, I get replacement shims of the size .106-.108 mm. What?!?!?!

Before I cracked the valve covers, I measured every clearance twice, to ensure I was getting the same thing, so I'm quite positive on the clearance numbers.

I double checked the shim I pulled out with a micrometer, so I'm positive on those values.

The numbers:

Cylinder #1, L hand exhaust valve (as you face the valves)

Clearance: .203
Old Shim: .153
Spec: .250

new shim=(measured - spec) + current shim
.106=(.203 - .25) + .153

The smallest shim I can find is a .120.

Any ideas/thoughts?
 
Joined
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'97 ST1100
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687
You're off by a decimal place on your shim sizes. Your old shim is 1.53mm. If you need to widen the gap by 0.250-0.203=0.047mm that means you would need a 1.48mm shim.

So now I have to ask, did you check all the other ones you adjusted to see if the clearance was correct after swapping shims? If you used the same math on the others, I suspect you miscalculated the other shim values.
 

Scooter

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I never liked using the formula because it over complicates things. The Hot Cams kits are usually setup so the increments between shim sizes is .05mm which is close enough to .002 inches.

I like measuring my clearances in thousands of an inch, here's why. Let's say I measured my exhaust valve clearance at .008" which is outside the nominal value of .010" by .002". All I need to do to move that clearance right back to where it needs to be is to pull the shim that was in the bucket, read the value and then go to the next smaller sized shim. Let's assume that the shim that was originally used was 1.60mm. If I replace it with the next thinner sized shim out of the kit, 1.55mm, I should expect the clearance to go back to .010" when I put everything back together and recheck my measurements.

If your clearance is to loose by .002", then you would need to go to the next larger shim size to get back to nominal.

What to do if the original shim is an in-between value of the Hot Cams kit? For example, you pull out a 1.575mm shim (marked 158) in the above example? You can't get to the nominal .010" value using the Hot Cams kit. You can either wind up with a clearance of .009" using a 1.55mm shim or you can have a clearance of .011" using the 1.50mm shim. Or you can go to the Honda dealer and get a 1.525 shim which will put you back at the .010" nominal.

Looking at your numbers, your clearance is .203mm which is about .008". The existing shim size should be marked 152 which is 1.525mm. To get back to .25mm you need to use a 148 (1.475mm) shim. But your Hot Cams kit doesn't have that one.

So use a 1.45mm shim if you want to be .001" loose (.011" clearance).

Or use the 1.50mm shim if you want to be .001" tight (.009" clearance).
 

John OoSTerhuis

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+1 Measure in thousandths.* Select a shim one size smaller or larger for each thousandth you want to change the clearance. No complicated math involved, just a Honda part numbers list of shim sizes and their markings. I've poSTed that here somewheres before. You can't get any closer unless you make your own shims.*
FYI FWIW YMMV

Edit: error on the side of loose for exhaust valves.
*Edit2: Honda shim increments: .025mm. And .001"=.0254mm [close enough! Method your dealer's service tech moST likely uses]

John
via iPhone 6
 
Last edited:

John OoSTerhuis

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There is no reason to do any conversions. The service manual also provides clearance specs in inches. You can't get any closer than one thousandth of an inch in adjusting the clearance gap. Measure in thousandths of an inch (use SAE feeler gages). If you want to change it, pull the shim and read the marking. Look at this list and select the desired shim, one size smaller or larger for each thousandth of change desired.

Honda Part Number / Thickness (mm) / Marking

14901-KT7-013 SHIM, TAPPET (1.200) 120
14902-KT7-013 SHIM, TAPPET (1.225) 122
14903-KT7-013 SHIM, TAPPET (1.250) 125
14904-KT7-013 SHIM, TAPPET (1.275) 128
14905-KT7-013 SHIM, TAPPET (1.300) 130
14906-KT7-013 SHIM, TAPPET (1.325) 132
14907-KT7-013 SHIM, TAPPET (1.350) 135
14908-KT7-013 SHIM, TAPPET (1.375) 138
14909-KT7-013 SHIM, TAPPET (1.400) 140
14910-KT7-013 SHIM, TAPPET (1.425) 142
14911-KT7-013 SHIM, TAPPET (1.450) 145
14912-KT7-013 SHIM, TAPPET (1.475) 148
14913-KT7-013 SHIM, TAPPET (1.500) 150
14914-KT7-013 SHIM, TAPPET (1.525) 152
14915-KT7-013 SHIM, TAPPET (1.550) 155
14916-KT7-013 SHIM, TAPPET (1.575) 158
14917-KT7-013 SHIM, TAPPET (1.600) 160
14918-KT7-013 SHIM, TAPPET (1.625) 162
14919-KT7-013 SHIM, TAPPET (1.650) 165
14920-KT7-013 SHIM, TAPPET (1.675) 168
14921-KT7-013 SHIM, TAPPET (1.700) 170
14922-KT7-013 SHIM, TAPPET (1.725) 172
14923-KT7-013 SHIM, TAPPET (1.750) 175
14924-KT7-013 SHIM, TAPPET (1.775) 178
14925-KT7-013 SHIM, TAPPET (1.800) 180
14926-KT7-013 SHIM, TAPPET (1.825) 182
14927-KT7-013 SHIM, TAPPET (1.850) 185
14928-KT7-013 SHIM, TAPPET (1.875) 188
14929-KT7-013 SHIM, TAPPET (1.900) 190
14930-KT7-013 SHIM, TAPPET (1.925) 192
14931-KT7-013 SHIM, TAPPET (1.950) 195
14932-KT7-013 SHIM, TAPPET (1.975) 198
14933-KT7-013 SHIM, TAPPET (2.000) 200
14934-KT7-013 SHIM, TAPPET (2.025) 202
14935-KT7-013 SHIM, TAPPET (2.050) 205
14936-KT7-013 SHIM, TAPPET (2.075) 208
14937-KT7-013 SHIM, TAPPET (2.100) 210
14938-KT7-013 SHIM, TAPPET (2.125) 212
14939-KT7-013 SHIM, TAPPET (2.150) 215
14940-KT7-013 SHIM, TAPPET (2.175) 218
14941-KT7-013 SHIM, TAPPET (2.200) 220
14942-KT7-013 SHIM, TAPPET (2.225) 222
14943-KT7-013 SHIM, TAPPET (2.250) 225
14944-KT7-013 SHIM, TAPPET (2.275) 228
14945-KT7-013 SHIM, TAPPET (2.300) 230
14946-KT7-013 SHIM, TAPPET (2.325) 232
14947-KT7-013 SHIM, TAPPET (2.350) 235
14948-KT7-013 SHIM, TAPPET (2.375) 238
14949-KT7-013 SHIM, TAPPET (2.400) 240
14950-KT7-013 SHIM, TAPPET (2.425) 242
14951-KT7-013 SHIM, TAPPET (2.450) 245
14952-KT7-013 SHIM, TAPPET (2.475) 248
14953-KT7-013 SHIM, TAPPET (2.500) 250
14954-KT7-013 SHIM, TAPPET (2.525) 252
14955-KT7-013 SHIM, TAPPET (2.550) 255
14956-KT7-013 SHIM, TAPPET (2.575) 258
14957-KT7-013 SHIM, TAPPET (2.600) 260
14958-KT7-013 SHIM, TAPPET (2.625) 262
14959-KT7-013 SHIM, TAPPET (2.650) 265
14960-KT7-013 SHIM, TAPPET (2.675) 268
14961-KT7-013 SHIM, TAPPET (2.700) 270
14962-KT7-013 SHIM, TAPPET (2.725) 272
14963-KT7-013 SHIM, TAPPET (2.750) 275
14964-KT7-013 SHIM, TAPPET (2.775) 278
14965-KT7-013 SHIM, TAPPET (2.800) 280
14966-KT7-013 SHIM, TAPPET (2.825) 282
14967-KT7-013 SHIM, TAPPET (2.850) 285
14968-KT7-013 SHIM, TAPPET (2.875) 288
14969-KT7-013 SHIM, TAPPET (2.900) 290

Total number of shim thicknesses available: 69
 
Last edited:

RCS

Joined
Jul 3, 2008
Messages
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Location
Stamford, CT
Hello and help!

The numbers:

Cylinder #1, L hand exhaust valve (as you face the valves)

Clearance: .203
Old Shim: .153
Spec: .250

new shim=(measured - spec) + current shim
.106=(.203 - .25) + .153

The smallest shim I can find is a .120.

Any ideas/thoughts?
I prefer using mm to measure clearances because Honda is a metric motorcycle with metric shims and the Hotshims kit is metric also. Converting to inches unnecessarily complicates every calculation and can easily lead to mistakes.

Easy rule. If valve clearance is too small, go with a smaller shim. If valve clearance is too large, go with a bigger shim. In the example below, it looks like the valve clearance is too small by about .05mm so go with a smaller shim. If the current shim is 1.53, go with either a 1.50 shim or 1.45 shim. A 1.50 increases the valve clearance gap by .03mm to .23mm, a 1.45mm shim increases the valve clearance gap by .08mm to .28mm.

To John's post above, if you have the choice to do either shim I would go with the 1.45mm shim because exhaust valve clearances in my experience get smaller with use.

The numbers:

Cylinder #1, L hand exhaust valve (as you face the valves)

Clearance: .203 .203mm
Old Shim: .153 1.53mm
Spec: .250 .250mm
 
Last edited:

John OoSTerhuis

Life Is Good!
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1991 SSMST1100
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1058
JMHO, but Hot Cams shim kits' increments are twice what Honda stocks (and what you may actually want). The STOC valve check/adjustment loaner tool kit has shims in .025mm increments. BTW, every Honda shim that I've ever measured with my quality metric micrometer has exactly matched the thickness identified as marked in the above list. There's a micrometer in the kit.

Again - no formulas required, no conversions necessary - use SAE (inch) feeler gages, you can only change valve clearances in increments of one thousandth of an inch. I do have metric feelers and foolproof/debugged spreadsheets and have used them, a number of times; which every time confirmed using the above simplified method works. Try it for yourselves if you doubt me...

John
via iPhone 6
 
Last edited:

Blrfl

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JMHO, but Hot Cams shim kits' increments are twice what Honda stocks (and what you may actually want).
They're enough to get any out-of-spec valve back into spec unless you're neurotic about being as close to centered as possible. I'm not, because the spec is what it is and you're either in or out.

--Mark
 
OP
OP
foilrat
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Messages
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Location
Seattle
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6571
To John's post above, if you have the choice to do either shim I would go with the 1.45mm shim because exhaust valve clearances in my experience get smaller with use.

The numbers:

Cylinder #1, L hand exhaust valve (as you face the valves)

Clearance: .203 .203mm
Old Shim: .153 1.53mm
Spec: .250 .250mm
Yup. I was off by a factor of 10. And I agree with you, since everything has tightened up over time, I'll go with looser if I have to choose.
 
OP
OP
foilrat
Joined
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Messages
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Location
Seattle
STOC #
6571
You're off by a decimal place on your shim sizes. Your old shim is 1.53mm. If you need to widen the gap by 0.250-0.203=0.047mm that means you would need a 1.48mm shim.

So now I have to ask, did you check all the other ones you adjusted to see if the clearance was correct after swapping shims? If you used the same math on the others, I suspect you miscalculated the other shim values.
Ohferfu....

Well crap. Is my face red? No? Yes? It bloodly well should be.

Yeah, my decimal was off. I was so used to thinking of the intake shims which were all less than a 1mm, that I didn't ever stop read it correctly.

Glad I didn't do anything stupid(er).

Thanks for the nudge in the right direction.
 
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687
Ohferfu....

Yeah, my decimal was off. I was so used to thinking of the intake shims which were all less than a 1mm, that I didn't ever stop read it correctly.
The thinnest shim Honda makes is 1.20mm

you may want to re-measure everything, it sounds like you may have strayed off track along the way.
 

RCS

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Yup. I was off by a factor of 10. And I agree with you, since everything has tightened up over time, I'll go with looser if I have to choose.
If you want to post the other 5 clearances and current shim sizes, we can post the recommended new shim sizes.
 
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