chutley
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| posted on 16/5/16 at 05:01 PM |
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Low Compression
ZZR1400 engine in an MK Indy, showed 175bhp at back wheel on Dyno and running great.
However, compression testing showed that compression is low on all 4 cylinders. Should be 149-228 PSI. All 4 are showing just 110PSI.
Advice please - should i get the Pistons and Rings changed? How urgent is the job?
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gremlin1234
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| posted on 16/5/16 at 05:08 PM |
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first I would try a different compression tester ;-)
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Hellfire
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| posted on 16/5/16 at 05:10 PM |
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Why did you check the compression in the first place and how long ago was it dyno'd?
Phil
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sdh2903
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| posted on 16/5/16 at 05:54 PM |
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Some engines specify doing a hot or cold test too.
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Andy D
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| posted on 16/5/16 at 05:55 PM |
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.. with the throttle wide open?
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chutley
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| posted on 16/5/16 at 06:08 PM |
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Tested with cold and hot engine - no difference. Throttle wide open.
Dyno'd a few months ago - strong 175BHP at back wheel, since then has done about 350 track miles.
Compression tested because of the heavy crank case breathing typical of Kawasakis. Oil in the catch tank smells strongly of petrol. I was wondering
if petrol was slipping past the rings, and compression test is all I'm equipped to do.
Is it safe to run for the season, or does it need attention now?
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britishtrident
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| posted on 16/5/16 at 06:59 PM |
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Do a wet compression test with the injectors disconnected, wide open throttle.
On injected engines compression testing with injectors firing washes the bores and has a major effect on compression.
It is likely to be a ring and bore wear problem. A valve problem is unlikely to affect all cylinders equally and a valve timing issue would affect the
power curve.
To diagnose further would need more equipment such aa a cylinder leakdown tester although are fairly cheap on eBay but require compressed air to
work.
The other available tests would need really specialist equipment an oscilloscope and an in cylinder pressure sensor.
[Edited on 16/5/16 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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chutley
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| posted on 23/5/16 at 07:34 PM |
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quote:
Originally posted by gremlin1234
first I would try a different compression tester ;-)
You were right!!! Local mechanic tested with a professional gauge (not a £25 e-bay gauge) and it is showing 210 PSI.
Out at Cadwell on Thursday, so we'll see how the breathing issue plays out. Hopefully the engine will just find its own level.
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CosKev3
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| posted on 23/5/16 at 08:11 PM |
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Does it smell of fuel in your oil filler cap?
If so I wouldn't be doing a trackday with that oil in it.
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chutley
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| posted on 23/5/16 at 08:14 PM |
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No, the oil I dropped last time was black and uncontaminated with fuel. However, the catch tank oil smells of fuel.
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skippad
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| posted on 23/5/16 at 08:57 PM |
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i've just done a brilliant trackday tonight at Teesside Autodrome and my engine ran faultlessly with the oil level that i mentioned to you,
hopefully yours will be the same at Cadwell!
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