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#1
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yamaha concern
looking at a 1992 yamaha 250 with 98 psi across the board. is this number a little low? thanks
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#2
09-26-2012, 05:06 AM
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I have had a few and they had that number with out issue. Yamaha's love to get carboned up!! That's why they all say to use carbon free when you fill up.
I used a Sea foam treatment on one of mine, and saw the compression go up 10 PSI across the board. It would not worry me if the rest of the motor checks out. Good Luck
__________________
1986 V20  Old Fishermen never die, we just SMELL that way!!
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#3
09-26-2012, 08:26 PM
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thank you Mj !!!!!!!!
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#4
09-26-2012, 08:38 PM
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also understand that a compression test is to be performed on a warm engine at WOT
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#5
09-27-2012, 09:28 PM
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Quote:
First, warm the engine up, You'll also need to disable your ignition system. You're going to need to crank the starter to turn the engine over but you don't want it to actually start. Then unscrew a plug and screw your adapter into the vacant hole, then screw in the hose leading to your gage into the adaptor. Turn the engine over a few revolutions... that's enough to get an accurate reading. Record the reading for that cylinder, then repeat on each of the other cylinders. They should all be within about 10 lbs of each other. That's all there is to it.
__________________
1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer 1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer 1996 V21 w/1993 200HP Mercury on a Shoreline Trailer All towed by a 5.7L Hemi Durango. If God didn't have a purpose for us we wouldn't be here, so Live simply, Love generously, Care deeply, Speak kindly. (Leave the rest to God) Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless. Last edited by Destroyer; 09-27-2012 at 09:50 PM.
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#7
09-28-2012, 11:41 AM
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Quote:
__________________
1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer 1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer 1996 V21 w/1993 200HP Mercury on a Shoreline Trailer All towed by a 5.7L Hemi Durango. If God didn't have a purpose for us we wouldn't be here, so Live simply, Love generously, Care deeply, Speak kindly. (Leave the rest to God) Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless.
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#8
09-28-2012, 12:47 PM
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check your gauge, I've got three different gauges that read 30 psi difference between them, I've a got a selling gauge
 , buying gauge , and one that reads correctly. Normally if they all read close to each other, thats all you need. I did an engine check out for a customer buying a boat, compresion on both engines came well withing spec around 125 psi. He called me after taking delivery all pissed off because his mechanic said both engines were worn out, he said his gauge read 80 psi. I told him to get another gauge and another mechanic. He called back two days later and apologzed to me, he took it to anotehr mechanic and it checked out OK
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#9
09-28-2012, 03:35 PM
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Whats wrong with thumbin the hole?? My right thumb is accurate to about 3psi. My left thumb however, is off about 6psi
__________________
- The charm of fishing is that it is the pursuit of what is elusive but obtainable, a perpetual series of occasions for hope. Lucky Jack - .......The Surprise is not old; no one would call her old. She has a bluff bow, lovely lines. She's a fine seaboat: weatherly, stiff and fast, very fast, if she's well handled. No, she's not old; she's in her prime. 85' Wellcraft 20 Fisherman "Guale Girl" 1979 Alumnacraft 14 - STILL got holes in it 2006 WS Tarpon160f - "Mudd Butt"
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#10
09-28-2012, 04:06 PM
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Quote:
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Linear Mode
