25hp Evinrude 1987

[AaronS76]

Hi all

87 25hp Johnson. I had a thread on getting it idling but am starting a new one because I played with it again today.
http://forums.iboats.com/forum/engi...oards/10335736-1987-evinrude-25-hp-idle-issue

What I know.

Compression in both cylinders 95 psi

Good spark

New spark plugs gapped at 0.3 inch

Fuel pump ok

Carby clean as a whistle

When I bought it the carby float was upside down. It is now up the correct way up and parallel to base of carby

When idle circuit screw fully seated I can still blow air through circuit (I thought this should not happen)

The butterfly has to be slightly open to get it to idle

Exhaust was coming from the base of the power head near where what looks like a crankcase pressure hose is connected.

The motor never idled but went like the clappers. I tried to get it to idle by linking and syncing and lost top end. It went downhill from there.

Anyone able to suggest where to next? Reeds? Sorting out idle circuit? Timing? Is there an idle timing suggestion? None is listed in manual.

Thanks in advance.

 

[flyingscott]

That compression is low I would start there. Pull the side covers or the head off and look at the cylinders.

 

[w2much]

95 lb compression is too low ?










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[w2much]

Your old thread says spark is only jumping 1/4" is that still the case?

 

[flyingscott]

95 lb compression is too low ?










/

YUP

 

[oldboat1]

maybe a typo, but spark plug gap should typically be .030. The spark intensity is measured with an adjustable spark tester and "good" spark would be measured spark of about half an inch. That should not be confused with the plug gap setting.

By saying the carb float is now parallel to the body, you probably mean level with edge of the inverted carb top. Just to be sure, look at a schematic of the carb: http://www.iboats.com/Carburetor/dm/...iew_id.1547990 The flat or uniform side of the float goes up into the top of the carb.

I won't tell you it won't run with 95 lbs compression, but my '80s 9.9s have 125 lbs. A different tester might give you different results -- could try that.

The front plate in the carb is the choke. The throttle plate is in back. The roller needs to first touch the cam at the scribed mark as you throttle up -- means the throttle plate will begin to open at that point. Prior to that, the roller is not in contact with the cam.

If the flywheel is seated exactly over the key, the timing will be correct.

 

[flyingscott]

There is no choke plate on that carb uses an electric or manual primer.

 

[oldboat1]

stand corrected....thanks Scott.