Compression Question

  • littlemanonbigbike
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Compression Question

06 Jun 2008 15:15
#218402
After searching the forum I am unable to find the answer to my question. Maybe i did'nt search deep enough. Anyhow my question. Does the KZ1000's and the KZ1100 spectre share the same compression psi? I have not had a chance to get a manual for my bike yet but I do have a service manual for the KZ1000. My bike runs 120psi on all cylinders after warmed up which seems low to me but don't know if i can go with what the KZ1000 manual says.
1982 1100 Spectre
Various other toys

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  • bountyhunter
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Re: Compression Question

06 Jun 2008 19:25
#218443
I don't have that service manual but the stock compression for my KZ-750 is 155 psi, and the absloute minimum service limit (warm) is about 115 psi. I would be surprised if the 1000 or 1100 were very much different.
1979 KZ-750 Twin

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  • APE Jay
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Re: Compression Question

06 Jun 2008 21:43
#218482
Are you checking that with the throttle wide open and all of the plugs out?

Jay

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  • littlemanonbigbike
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Re: Compression Question

07 Jun 2008 07:07
#218516
Test was done with throttle open and all of the plugs out and the engine warmed up. I ran the test with the engine cold and the psi dropped to 100 psi verses the 120 warmed up.
1982 1100 Spectre
Various other toys

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  • MCH650SR
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Re: Compression Question

07 Jun 2008 08:17
#218521
I'm just wondering. How does the bike run? If it's running good, I wouldn't worry about the compression. Your compression numbers could be a false reading.
Just enjoy the ride.
1979 KZ650SR
modified with BS32 carbs
Yoshimura 4 in1
2006 Kawasaki Sherpa
1979 Honda CX500
BC Canada

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  • littlemanonbigbike
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Re: Compression Question

07 Jun 2008 09:42
#218537
I think it runs good. It starts with no problems and seems to have plenty of power. Every now and then I will get a little smoke from the pipe (4 into 1)but very little. The bike sat for 7 years before i got it maybe the rings were sticking a little don't know. Also, there is a little seepage around the head gasket I thought maybe could be contributing the low readings. I have a complete gasket set on the way to take care of it.
1982 1100 Spectre
Various other toys

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  • Patton
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Re: Compression Question

07 Jun 2008 09:49
#218541
littlemanonbigbike wrote:
I think it runs good. It starts with no problems and seems to have plenty of power. Every now and then I will get a little smoke from the pipe (4 into 1)but very little. The bike sat for 7 years before i got it maybe the rings were sticking a little don't know. Also, there is a little seepage around the head gasket I thought maybe could be contributing the low readings. I have a complete gasket set on the way to take care of it.

little seepage around the head gasket -- pic?

Thinking maybe tach drive, or exhaust gasket, or . . . (and perhaps not the head gasket).

Good Luck! :)
1973 Z1
KZ900 LTD

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  • bountyhunter
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Re: Compression Question

07 Jun 2008 12:10
#218573
Check valve clearance to make sure they are seating fully. If they are, you can ride it until it runs lousy and then do the head job.
1979 KZ-750 Twin

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