motor big enough?

rhbowler · Jan 12, 2013

Hi, new to the forum, so hope this is the right place to ask this. I Just bought a 1986 1910 Bayliner Trophy CC. It has a tired 125hp Force on it now. I also have a bass boat with a Johnson Stinger 85hp in excellent shape. What i'm wondering is if putting the 85 on the boat would be a good choice, or should I get a good used 115 to 130hp motor. Would the 85 be underpowered on this boat? I use it in the Ocean here in So California. Thank you for any input on the matter.

jestor68 · Jan 12, 2013

Re: motor big enough?

Most Bayliners, 19 ft and up, had 25" transom heights. So I would verify the transom height first.

An 85 might power that boat to maybe 30 mph.

I would suggest nothing less than the 125 that came on it. Bayliner could have put an 85(the next lower Force power choice in 1986) on it from the factory, but they put the 125(the biggest Force motor at the time) on there for a reason. With the 125, that boat did about 37-40 mph; barely acceptable performance.

That boat/motor weighs 2000 lbs(dry), so with 800 lbs of people/gear, and 30 gal of gas; we're talking about 3000 lbs to push in a deep V hull.

What's the max power rating(150?)? I would go for that if I wanted decent performance.

dingbat · Jan 12, 2013

Re: motor big enough?

Bayliner could have put an 85(the next lower power choice in 1986) on it from the factory, but they put the 125(the biggest at the time) on there for a reason.

The largest outboards made at the time where 225HP. They put a 125 HP on that boat to keep a price point.

With the 125, that boat did about 37-40 mph; barely acceptable performance.

I have one of those boats with ?barely unacceptable performance? (42 MPH) but it will run that speed under conditions that most 50 MPH boats will not leave the dock. 42 MPH on the water or 50 MPH sitting on the trailer? :lol::lol:

Nothing more dangerous than being caught in conditions where you do not have the HP to maintain control of your boat. Inlets eat more than their share of underpowered boats.

rhbowler · Jan 12, 2013

Re: motor big enough?

Where do I measure the transom height from? I sure hope it's 20 not 25, I have found a few good 20" shaft good used motors in the 115 to 130hp range, but 25" seem to be scarce. Thanks for your reply, and the boat is only rated for 130hp, so unfortunately a 150 is out.

JB · Jan 12, 2013

Re: motor big enough?

Measure your transom by dropping a VERTICAL line from the top to a point level with the keel. Do not measure it on the surface of the transom.

If the boat is rated for 130HP the 85 falls short of the 70% rule of thumb for acceptable performance. The 125 should be a good match for that boat if it is in good running order.

I would do a thorough diagnostic "physical" on your Force; compression test (as outlined in the Engine FAQs forum) comes first. Then do a complete link 'n' synch. Let us know what you get.

If you are determined to repower don't go below 100HP but you would be a lot better off with your 125 brought up to snuff.

roscoe · Jan 12, 2013

Re: motor big enough?

Frank Acampora · Jan 12, 2013

Re: motor big enough?

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It doesn't matter what brand engine you hang on it, 85 horsepower simply will not be enough for your use. It would be acceptable on protected water where you might want to putter around and fish but simply not enough for ocean use.

What makes you think the 125 is "tired?" If it not performing uop to new engine output, it can be rebuilt relatively inexpensively and same goes for replacing ignition components. My vote would be to bring it back to factory specs.

Now, here is a 21 foot cuddy that was used exclusively on east coast oceans at Jersey. I bought it whe a Force 125 and it did 33-35 MPH. I replaced the perfectly good Force with an older Chrysler 140 for a couple of MPH more.

I find the 140 sufficient for boating on the Chesapeake, but when I go to Barnegat and out the inlet into the ocean, it is marginal. I am lookint to repower up to the maximum 180 for which it is rated.

NYBo · Jan 12, 2013

Re: motor big enough?

dingbat said:
The largest outboards made at the time where 225HP. They put a 125 HP on that boat to keep a price point.

I think he was referring to the largest Force outboard at that time; that was all Bayliner used because they were part of the same company.

H20Rat · Jan 12, 2013

Re: motor big enough?

NYBo said:
I think he was referring to the largest Force outboard at that time; that was all Bayliner used because they were part of the same company.

yep, thinking the same thing... Bayliner stuck force's on every model going out the door for that time period, 125hp was simply the biggest you could get on that boat from the factory.

jestor68 · Jan 12, 2013

Re: motor big enough?

NYBo said:
I think he was referring to the largest Force outboard at that time; that was all Bayliner used because they were part of the same company.

Yes, that's exactly what I was referring to; the fact that Bayliner equipped their outboard powered boats from the factory with Force motors.

aspeck · Jan 12, 2013

Re: motor big enough?

Been said here already ... but I would go somewhere between a 115 and the maximum HP rating. You won't be sorry in the long run.

rhbowler · Jan 12, 2013

Re: motor big enough?

Thanks guys, appreciate the responses. I have a line on 3 different motors, a 115 Merc Tower of Power, 110 Johnson V4, and a 115 Suzuki, all are in excellent shape, so i'm leaning toward the Suzuki actually. The Froce is making a light tapping noise above 3000 RPM, and the power trim/tilt mechanism is non functional. The boat is in the water now, i'm putting it back on the trailer next week so I can see if perhaps the PT is just low on oil since the motor runs, it just doesn't raise the motor at all.

MWG2600 · Jan 12, 2013

Re: motor big enough?

from where the engine mounts to the bottom of the boat.

Frank Acampora · Jan 12, 2013

Re: motor big enough?

Light tapping noise at or near wide open throttle can be pre-ignition due to a lean carb or over-advanced timing. Pull all four plugs and check the condition of the top of each piston. If any piston has pitting, then remove the carbs and clean them. Check that full advance is 30 degrees before Top Dead center. Do this BEFORE running the engine again as continued "pinging" will lead to detonation and melted piston(s).

Go to the Force forum and click on FAQs: "synchronizing carbs and timing" for correct settings.
Here are some photos of severe detonation damage due to uncorrected lean running.

motor big enough?

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