'88 Merc 45 hp weak on top end

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fastfred2818

Recruit
Joined
Sep 11, 2012
Messages
4
I have an '88 Merc 45 hp Classic Fifty on a 17" Bass Tracker. Motor starts and runs fine at low to mid range. At wot will only turn 4000 rpm@28 mph. Motor runs smooth with no noticable miss. Pluge are new. Fuel system has been cleaned, carbs and fuel pump just rebuilt. Compression is 120-125 all 4 cyls. Motor will rev 5500+ in driveway. Any suggestions?
 
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oldman570

Lieutenant Commander
Joined
Mar 25, 2011
Messages
1,615
Re: '88 Merc 45 hp weak on top end

First off NEVER rev a motor when it is on muffs, as there is no backpressure on the motor then, and a good chance damage will be done. If the motor runs good more than likely it is over proped. A boat that size should not have more than a 12 or 13 pitched prop on the motor because it sounds as tho it is over working the motor.Might even need to go to a 11 pitch to get the motor running at the recommended 5000RPM for the 50 Classic. Thats a good size boat for that small motor and a bigger motor in the 75 hp would be better on a boat that size. JMO
Oldman570
 
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