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Post-adjustment valve issues?
- serfrock
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Sorry if this has been addressed; I didn't have much luck in searching. I also apologize in advance that I don't have many specifics at the moment, but I'm at work without my notes from the weekend.
I just got done attempting my first valve adjustment on the KZ, and I'm a little confused. I measured the clearances, bought the appropriate shims to get the clearances somewhere in the middle of the (.08 - .18mm) range, and buttoned the whole thing back up. Most of my valve clearances were too tight, so I bought thinner shims to compensate.
After double-checking the clearances, a few of them are smaller than they were to begin with, a couple now as narrow as .04mm! Another few should have opened up to slightly greater than 0.15mm, but I can't get a .15mm feeler in between any of them.
I'm confident in my original measurements and that I put the right shims under the right buckets. My camshafts were bolted to the appropriate torque (albeit with not-the-greatest torque wrench from Harbor Freight), in the correct sequence, and with proper timing.
Has anyone has had the same experience? Or is there anything I can check before I start taking the camshafts out again?
Thanks!
1979 KZ650 C3 (in progress)
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- Topper
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Also be sure the cam lobe is pointing 180 degrees away from the valve stem when you're measuring.
Permanent and perpetual noob.
1979 KZ750 Twin
2009 Kawasaki Versys
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- serfrock
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1979 KZ650 C3 (in progress)
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- baldy110
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- sbc1320
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1980 KZ1000 LTD-B4(MK II engine) - Progressive suspension, MTC pistons, Dynojet Stage III, all wear items replaced, WFO paint scheme(1978), etc..
Past bikes- 2 1976 Kz900's, 5 1975-76 Honda CB750's, Honda 500 -4, Honda 250, Honda 125, Honda 100, Suzuki RM 250, Honda XL350, Kawasaki KLR 650, etc..
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- serfrock
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It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?
1979 KZ650 C3 (in progress)
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- bountyhunter
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serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.
It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?
possible if they are worn. Another thing: when checking clearances, make sure to only turn engine in normal direction, don't reverse. That can release the tension on the cam chain and let the cams rise up a bit. I have seen that change valve clearances by a couple of thousandths.
1979 KZ-750 Twin
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- sbc1320
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serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.
It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?
Numbered side always goes down. If it's worn very much I chunk them in the trash.
1980 KZ1000 LTD-B4(MK II engine) - Progressive suspension, MTC pistons, Dynojet Stage III, all wear items replaced, WFO paint scheme(1978), etc..
Past bikes- 2 1976 Kz900's, 5 1975-76 Honda CB750's, Honda 500 -4, Honda 250, Honda 125, Honda 100, Suzuki RM 250, Honda XL350, Kawasaki KLR 650, etc..
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- steell
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sbc1320 wrote:
serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.
It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?
Numbered side always goes down. If it's worn very much I chunk them in the trash.
If the shim is worn enough to trash it, then you probably ought to look for new cams also, I think they are both about the same hardness, so the cam is probably worn also.
Way back when, Chevy let a bunch of non hardened cams get installed in their 350's, cams didn't last very long as the lobes were worn off the cams.
KD9JUR
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- RonKZ650
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321,000 miles on KZ's that I can remember. Not going to see any more.
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- LarryC
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With whatever shims you have in the engine now..... Point the lobe directly away from the bucket so that the tip of the lobe is in line with the valve stem, pointing opposite the valve head..
Check your lash right there. Forget that silly chart altogether. Based on your lash reading, go up or down in shim size to get the lash correct. It's quicker if you have mics or calipers to measure the shim you take out and also the shim you want to use.
Doing it this way, you are 100% assured you are on the base circle of the cam, in a particular spot on the base circle where there should be no abnormal wear influencing your readings. Also, that is the position on the cam where the valve is absolutely closed [providing there is actually lash].
If you try going by the portion of the base circle that is immediately following he opening ramp of the lobe, you can run into situations where abnormal wear will yield a reading that doesn't match the reading you get using the "lobe away" method.
Larry C.
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- WABBMW
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One final thought, although unlikely... Is it possible that a previous owner ground some shims down thinner, on the opposite side from the numbers, so that the actual thickness is less than what is marked? This is a bad practice since the hard coating might have been ground through, but it would explain why the clearance was reduced after those shims were replaced with ones that were truly the thickness that is marked. You might measure a few of them to see if they are the thickness that is marked. Just a wild thought.
Bill Baker
Houston, Texas
1982 KZ650 CSR
2008 Yamaha FZ1
2006 Yamaha FZ1
1977 Honda Supersport 750 four (sold)
1984 Honda Nighthawk 650 (sold)
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