75 HP to 90 HP Mariner Conversion


Old 10-06-01, 06:15 PM
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I just bought a pontoon boat with a '91 - 75 HP Mariner. The owner's manual is for both a 75 HP and 90 HP, and it indicates displacement (bore & stroke) is identical for both motors. I therefore assume the primary difference is in carbueration.

What would it take to convert this engine to 90 HP?


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Old 10-09-01, 03:33 AM
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Wink More power...

Rick, not to co-opt your question, but I have a '94 Force 70hp and have the same question. My single carb seems to be the only thing holding it back. On paper, the two motors (70hp and 90hp)seem otherwise identical. Anybody know if there's a difference in the powerhead/intake? Can we just slap the tri-carb setup on and go?
Old 10-12-01, 06:08 PM
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Im not positive about the mariners but on the johnsons there is an exhaust tuner which helps with the HP
also the size of the plenum matches the bore of the carb, just putting on a bigger one would get choked down at the intake.
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