low compression

  • TattooMark
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low compression

02 Jan 2010 23:16
#341672
Hello All... I have an 81 kz750 and i have low compression!! :( I am in the process of taking the motor out... anyone have any suggestions on what I need to look for first and if anyone else has had this problem? Thanks

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  • Nebr_Rex
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Re: low compression

03 Jan 2010 03:57
#341676
Is it rings or valves?
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/index.php?threads/dr-je...air-of-kz400s.39120/


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  • mark1122
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Re: low compression

03 Jan 2010 04:20
#341678
re-do the compresion test.remember to hold the throttle wide open when doing the test.
do it once dry, and once with a bit of oil in the cyl. the oil will seal the rings. if the compresion comes up, its the rings. if it stays low, its still leaking by the valves. check the valve clearance.
a leak down test is also helpful, but if the rings leak bad , its hard to hear any leakage at the valves.
76 KZ, frame gusset work,1200CC.Ported by Larry Cavanaugh, 1.5mm.over intakes, Carron Pipe, ZRX12 rear end, and seat,96zx9 front end.
01 CBR600F4i Track bike.
Cobourg, Ont. Can.

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Re: low compression

03 Jan 2010 06:07
#341685
mark1122 wrote:
re-do the compresion test.remember to hold the throttle wide open when doing the test.
do it once dry, and once with a bit of oil in the cyl. the oil will seal the rings. if the compresion comes up, its the rings. if it stays low, its still leaking by the valves. check the valve clearance.
a leak down test is also helpful, but if the rings leak bad , its hard to hear any leakage at the valves.

+1
This is good advice. If you havn't already done the compression test this way, then repeat before you get that thing out.
1978 KZ1000 A2 Click--->Build Thread
2004 ZX-10R
2007 Harley Sportster 1200
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Angola, IN

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  • TattooMark
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Re: low compression

03 Jan 2010 09:25
#341693
Thanks guys for the advice, I know what i will be doing this afternoon :)

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