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Strange Vacuum Reading
- bigkaw815
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Does this sound right? I wonder if someone could suggest what to do. Simply re-shim the valves or take the head off and check for damage? Had the head off recently to replace head gasket, and it all looked good inside.
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- bountyhunter
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If the vacuum reading fluctuates within the normal range-the gauge needle bounces around a lot-uneven compression (broken rings or leaking valves or head gasket in one or two cylinders) is a likely culprit. An uneven air/fuel mix, erratic ignition timing, a misfire, misadjusted valves or a manifold leak near one or two cylinders also are possible causes.
If vacuum drops intermittently at idle, one or more valves may be sticking open or dragging. Higher-than-- normal vacuum at idle is a common clue to overly advanced ignition timing, while low vacuum can indicate retarded timing.
findarticles.com/p/articles/mi_qa3828/is...08/ai_n8978956/pg_2/
1979 KZ-750 Twin
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- Old Man Rock
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"I got a single vacuum gauge today in hopes of syncing my carbs the cheap route one by one. "
THIS IS IMPOSSIBLE TO DO!!!!
THERE IS NO POSSIBLE WAY YOU CAN ACCURATELY ACCOMPLISH!!!
Even with my brand new CR specials, one carb tweak effects the others... You will be chasing this all over the place trying to dial in the syncing of your carbs...
You think you have erratic idle now, wait till you see what happens after trying to do this with one vacuum gauge... Seriously, all you will do is totally hose your carbs up!
Jeff @ Z1 or JPCycles offers a set of 4 analog gauges for ~ $60-$80.... Do yourself a HUGE favor, buy a set of 4...
With that said, if your valve clearances are not within spec then yes, get this right first... Shims!
But for KZ Gods sake, buy a set of 4....
OMR
BTW, Did I mention buy a set of 4 gauges...
www.z1enterprises.com/detail.aspx?ID=2727
www.jpcycles.com/Search/ProductDetail?sk...e&Ns=&results=10&No=
1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter
Phoenix, Az
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- flht1997
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Matt Milwaukee, WI
75' KZ400, (5) 78' KZ400, 76' KZ 750, 78' KZ650
78'CB750F, 78' CB550K
89' BMW R100RT
05' H-D Electra Glide
06' KLR650
Do it right or don't bother doing it at all.
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- Old Man Rock
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1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter
Phoenix, Az
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- 650ed
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1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- bigkaw815
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P.S. I promise to buy a 4 gauge vacuum meter. It was not all waste though, I can use the Harbor Freight Special on my 67 T-Bird
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- bigkaw815
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- Old Man Rock
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I don't have the 650 Manual so maybe yours does...
In the manuals you should find something similar to what's in my KZ900 shop manual...
Basically you measure where your at now, find it in the column and scroll down to what size is recommended to get you within specs....
1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter
Phoenix, Az
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- bigkaw815
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- OKC_Kent
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When everything is installed and properly timed for clearance checking, can you at least rotate the bucket? If you can rotate it but not get a feeler in there, then consider it to be zero clearance. If the bucket won't rotate then you have to buy the 2.00 mm shim and install it. Check the clearance again, etc.
Proceed to check all the valves, then pull the shims out and use a mike or vernier caliper to measure the thickness (convert to millimeter); then apply the shim size and valve clearance to get proper shim from the chart.
Some shims may be marked with the thickness but trust me not all marks are correct. I have shims that are one size off from the mark so MEASURE them.
You may find that you can swap some shims between valves. If you're lucky a Kaw service tech may swap shims with you and it won't cost anything.
Oklahoma City, OK
78 KZ650 B2 82,000+ miles
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- Johnj
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I highly recommend you get a set of metric feeler gauges. That way you're not converting inches into mm all the time.
I have found engines with the correct shims but in the wrong buckets before.
Veho vivo - Ago ut veho
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