100 HP Commerical to 200-225 HP powerhead

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daron

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Sep 1, 2008
Messages
5
I have a 1995 100 HP commerical Johnson with a 30" V6 gear case and a 100 HP V4 power head. The engine runs well, but my boat requires much more horsepower. Actually, I'm short nearly 120 HP. So, I was wondering if I could purchase a 200 or 225 powerhead and mount it on the V6 gear case-30" drive shaft. I don't have the funds for an entire new engine and I really don't want to remove the outboard. So my questions are:

1. Can I repower my outboard without removing the entire engine?
2. Do I need new cables? (my steering and throttle are OK)
3. What power head years will fit my 1995 V6 gear case?

It's a project boat and cost is a serious issue.
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 100 HP Commerical to 200-225 HP powerhead

If that's the gearcase that came with the motor it's not really a V6 unit. The gear ratio is a lot different even though the size is the same. The V6 powerhead will not bolt up to the V4 adaptor plate. It's actually a lot less work to change motors rather than to do what you're thinking about.
 
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daron

Recruit
Joined
Sep 1, 2008
Messages
5
Re: 100 HP Commerical to 200-225 HP powerhead

Thanks for the advice.....

Do you think replacing the orifice plugs in the 100 HP V4 carbs with 115 HP V4 carbs will allow me another 15 HP? I'm trying tme best to get more horsepower.

My oil alarm went off and my RPM's now won't go over 2500. The motor idles well and runs at idles forward, but the alarm goes off when RPM's go over 2500. Any ideas? I'm thinking of going pre-mix gas an pulling the VRO.
 
ondarvr

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: 100 HP Commerical to 200-225 HP powerhead

If the jets in the carb are different between yours and a normal 115 then putting the bigger jets in will only make it run worse.

Is the alarm continuous, or beeping?
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 100 HP Commerical to 200-225 HP powerhead

"My oil alarm went off and my RPM's now won't go over 2500." overheat alarm, motor going into slow mode, to protect motor.
 
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