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KZ650 valve clearance wierdness
- DoctoRot
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- Motor Head
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Otherwise, do it on a cold engine as that is the spec. If in doubt, rotate the motor over by hand another rotation and recheck the same valve. You can use the chart thats in "File Base". Take a complete measurement of all of them, go back and double check it. Then make the adjustment to 1 valve at a time, rechecking as you go.
1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...
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- ezrider714
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However I wouldn't adjust and re-check 1 at a time..This is why people talk about stripping out the cam cap screw threads..
If I've checked them twice and I usually check 4 or 5 times, Then do the math, get the shims needed(verify the thickness with calipers,as this is often part of the problem, the shims not being as close to the stated thickness as they should be) and put it all together 1 time..follow the procedure in the FSM for making sure to seat the shims.... Check the clearances several times, kick it over a few times and check again.... I've had very few that have required taking the cams back out...... Sure it might happen but so might a lot of things
78 KZ650SR Mine since 79
4-1 Mac Jet Hot coated since mid 80's
Dyna Coils
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- DoctoRot
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I guess maybe my shims aren't close to the stated thickness. but this doesn't explain one of the shims i did not touch changing a whole 0.10mm. I found a place that will sell me shims locally, so i guess ill go down there with a caliper and measure them for the ones i need.
They aren't too far from spec but i LOVE how smooth this engine is when they are dead on. soooo easy to start, not even half a kick and it will start.
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- DoctoRot
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- Nessism
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As for inconsistencies in the measured clearance is concern, the cam positioning method has an affect on this. For example, if you use the simple method of pointing the cam lobe away from the valve before measuring clearance, the adjacent valve will likely be pushing up against the cam and skewing it within the journal clearance. Measuring the valve then will result in the maximum amount of clearance possible. If on the other hand you position the cams like suggested in the manual, then the adjacent valve will be on the base circle and the clearance will be less than using the method detailed previously, because the valve won't be pushing up on the cam. I don't know if this explains the situation at hand, but it bears mentioning.
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- ezrider714
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78 KZ650SR Mine since 79
4-1 Mac Jet Hot coated since mid 80's
Dyna Coils
Saddlebags (I ain't skeered of going nowhere)
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- ezrider714
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78 KZ650SR Mine since 79
4-1 Mac Jet Hot coated since mid 80's
Dyna Coils
Saddlebags (I ain't skeered of going nowhere)
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- bountyhunter
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I have a couple of valves that will change clearance based on cam chain tension. There is up/down play of the camshafts in the journals and if I revers direction on the crankshaft nut while checking (and release cam chain tension) the clearance would change about .002" on a couple of valves.DoctoRot wrote: I'm checking the valve clearances on a 78 KZ650 and 3 are out of spec. I order 3 of the proper size, install and check all of them again. I got completely different measurements across the board! One valve went from a .08 clearance with a 235 to a .20 clearance with a 230. Another valve that went from a 245 to a 240 stayed the same. What the heck is going on? This happened to me the last time I checked the valve clearances on this bike and had to do it 4 times until I had them in spec because they kept changing. It was warmer than when i checked them initially but maybe 15F degree difference tops. i suppose that would effect it some because the shims i did not change or even touch were any where from .03 to .05 tighter than when i first checked them. Any tips? I don't want to have to deal with taking the cams in and out 4 times again.
For consistency, make sure to turn the crankshaft only forward and don't reverse direction when checking.
ALSO: the cam cap bolts do strip easily. I recall the spec is about 110 inch-pounds maximum but do not push it, 100 I-P is enough. You must have a low range torque wrench. I recall the one I got at Harbor Freight is 200 Inch-pounds full range so it can do 100 I=P very accurately.
1979 KZ-750 Twin
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- DoctoRot
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- bluezbike
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I am a bit surprised that there is up/down play in the camshafts......I didn't think there should be any play at all, am I missing something here?
79 KZ 1000 LTD
77 KZ 1000 B1 LTD (awaiting electrical resurrection)
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- Nessism
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bluezbike wrote: I am a bit surprised that there is up/down play in the camshafts......I didn't think there should be any play at all, am I missing something here?
There is clearance between the cam journal OD and the ID of the cam caps and head. The cam wouldn't rotate otherwise.
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