Question on Upgrading - 70 HP to 90 HP

[johnjsa]

I have a Bomber bas boat rated for 75 hp & currently have a 1977 Johnson 70 HP on it. I found a 1986 JOhnson 90 HP at a good price. What are pros & cons on putting the 90 on my boat?

 

[Texasmark]

Re: Question on Upgrading - 70 HP to 90 HP

You are just asking for trouble, and I don't mean mechanical.

Mark

 

[ezmobee]

Re: Question on Upgrading - 70 HP to 90 HP

iboats does not endorse overpowering your boat.

Also, 90 is a lowest horsepower V4 motor of that vintage. So you'd potentially be adding weight for little gain. Your 3 cyl 70 has one of the best HP-to-weight ratios available. If you want better performance I'd work on your setup before replacing the motor.

 

[tashasdaddy]

Re: Question on Upgrading - 70 HP to 90 HP

agree ^^^^

 

[Texasmark]

Re: Question on Upgrading - 70 HP to 90 HP

On performance as ezmobee mentioned: I once had a 70 hp on a 15' KingFisher; both being real popular in the later '70's and 80's around here. If you are not familiar with the hull shape, it was similar to the early Ranger bass boats that were becoming available at the time, especially in the area of the hull shape, but was not the same boat in construction nor cost. The engine had no TT.

Anyway, I jacked up the engine using a pieced of 1x2 redwood, increased the pitch of the prop (don't remember how much) and that boat ran like a scalded ape. I couldn't believe it was the same boat. Can't imagine what I could have done with TT and a proper set of instruments. So, like he said, work on your setup and you may be amazed at what you can get from your LEGAL sized engine.

My 2c,

Mark

 

[GeneH]

Re: Question on Upgrading - 70 HP to 90 HP

One of the major cons is that, if you are ever involved in an accident, you may not enjoy sleeping in a cardboard box when you lose your house, car, and boat to a lawsuit. If you can run the outfit on your own private lake with nobody else around, have at it-otherwise forget about it!

 

[CharlieB]

Re: Question on Upgrading - 70 HP to 90 HP

The guys are trying to tell you in a polite way that it is NOT a very good idea.

Many states have passed laws against over-powering boats, by ANY amount, to reduce accidents and fatalities.

Insurance Co's will cancel you if they even THINK you are over-powered, at all.

I've had to recover boats sunk at the dock (on a private lake) because the SLIGHTLY over-powered motor sat the boat low enough that minor waves came over the back, and gradually settled it down, to the end of the lines. The top 2 inches of the motor cover was still in the air. (115's in place of 75's and 85's).