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Outboard motor compression
#14086625
08/06/21 11:53 PM
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Joined: Jun 2004
Posts: 603
Crappieshooter
OP
Pro Angler
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OP
Pro Angler
Joined: Jun 2004
Posts: 603 |
Is 95 psi enough compression for an outboard motor. Looking at buying a boat and was told the compression check showed 95 psi on all cylinders. Good or bad?
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086666
08/07/21 12:51 AM
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Joined: Apr 2008
Posts: 12,345
PaulGrapevine
TFF Guru
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TFF Guru
Joined: Apr 2008
Posts: 12,345 |
2 stroke or 4 stroke motor? If it’s a 2 stroke then I’d be okay with it.
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086696
08/07/21 01:22 AM
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Joined: Mar 2014
Posts: 4,634
Topwater2
TFF Team Angler
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TFF Team Angler
Joined: Mar 2014
Posts: 4,634 |
FishKen
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086725
08/07/21 01:50 AM
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Joined: Jan 2005
Posts: 21,830
Pat Goff
TFF Guru
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TFF Guru
Joined: Jan 2005
Posts: 21,830 |
Depends on the motor. 95 is fine on a old Johnson. On a V6 merc it would be sick.
Pat Goff Seadrift TX
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086776
08/07/21 02:45 AM
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Joined: Sep 2003
Posts: 1,896
Coolarrow
Extreme Angler
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Extreme Angler
Joined: Sep 2003
Posts: 1,896 |
My old 96 Johnson 150 has 120 on all 6 so I’m not sure. What kind of motor and year? The
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086785
08/07/21 02:50 AM
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Joined: Sep 2003
Posts: 1,896
Coolarrow
Extreme Angler
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Extreme Angler
Joined: Sep 2003
Posts: 1,896 |
I know a 90 hp has about 120 psi in that year model range.
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086822
08/07/21 03:23 AM
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Joined: Aug 2010
Posts: 620
FlyFX
Pro Angler
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Pro Angler
Joined: Aug 2010
Posts: 620 |
always take a compression gauge, some lube and a plug wrench to survey a boat
Most people double haul so they can throw their mistakes further - Bernard "Lefty" Kreh - R.I.P. Glass rod, click & pawl, ugly flies
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Re: Outboard motor compression
[Re: Crappieshooter]
#14086859
08/07/21 04:14 AM
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Joined: Jan 2005
Posts: 21,830
Pat Goff
TFF Guru
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TFF Guru
Joined: Jan 2005
Posts: 21,830 |
Compression gauges can vary from one to another. What you’re really looking for is a misfit cylinder. Sick motor will have five at 120 and one at 90. On your three cylinder take all the plugs out, pull the kill switch and spin each hole. If they are all the same it’s what you want. If one is more than 10% different there is an issue.
Pat Goff Seadrift TX
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Re: Outboard motor compression
[Re: Crappieshooter]
#14087865
08/08/21 04:00 PM
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Joined: May 2011
Posts: 1,903
pil,b
Extreme Angler
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Extreme Angler
Joined: May 2011
Posts: 1,903 |
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Re: Outboard motor compression
[Re: Crappieshooter]
#14096530
08/16/21 03:17 AM
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Joined: Jun 2004
Posts: 603
Crappieshooter
OP
Pro Angler
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OP
Pro Angler
Joined: Jun 2004
Posts: 603 |
Thanks for the replies, passed on the motor.
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Re: Outboard motor compression
[Re: Crappieshooter]
#14103296
08/21/21 03:55 PM
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Joined: Nov 2002
Posts: 4,439
Gamblinman
TFF Team Angler
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TFF Team Angler
Joined: Nov 2002
Posts: 4,439 |
Compression check is really only to determine if you have bad cylinder. If you want to know the real health of an engine, a leakdown test should be performed.
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