Force 125hp speed issue

[Maine Fish Fan]

Hello Everyone, I have a 1991 Bayliner 2050 capri with a 1987 or 1988 125hp force engine I just put on. When I bought the boat it had a 1991 120hp force engine and would do 42 MPH with RPM at 5300 not sure the pitch prop it had. I have learned alot since then and just put the 125 on it it has a 19 pitch prop on it and at WOT it is at 4100 RPM and 30MPH the compression is 130 across the board, new plugs, new fuel pump, carbs dismantled and cleaned, engine decarbed, throttle is working correctly when wide open, new and clean fuel, checked speed with GPS, 2 differen Tachs used to double check. The Thing takes off fast out of the hole idles great. Any ideas on how to get the top speed up? I am confused because it takes off fast. And I think lowering the pitch to 17 would lower top speed just not sure wich way to go here any help would be great.

 

[foodfisher]

Re: Force 125hp speed issue

A prop pitched for higher speeds is the only thing I can offer, but you'll lose quick hole shots. The prop forum will specify details.

 

[Jiggz]

Re: Force 125hp speed issue

Have you verified timing? Improper timing will also limit your WOT. Are the carbs original? The jets are of the correct size? And throttle in horizontal at WOT (no more no less)? No exhaust leaks inside the cowl recirc'ing into the carbs?

 

[jerryjerry05]

Re: Force 125hp speed issue

Check for spark?Plugs burning right?
Make sure the carbs are set right.Top post,linc and sinc.
A 20ft with a 120/125 should have around a 17p prop.
If the 19 you have is only getting 4100rpm's then a 17 won't raise it that much.
Is the motor mounted right?
Cavitation plate even with the bottom?
Trim working?

 

[Maine Fish Fan]

Re: Force 125hp speed issue

Thanks for the quick answers. I have not verified timing is it hard to do? do I need a timing light to check it? carbs are original I have a set from a 1991 150 wasnt sure if I should put those on they are a little different and didnt want to screw anything up. I will check for exhaust leaks. Spark on all four pistons got a real good zap to prove it. Motor is mounted correctly same size boat came with from factory. trim will not stay up it goes down as soon as you let off the up button I think its the ram but havent gotten into that. It worked on the old motor and when I switched motors I moved the trim power unit only and filled it but havent figured out if it needs to be bled or defective ram on this motor. should I be running at WOT with trim up a little? I do not know how to tell if carbs are set right. I adjusted the idle screws it idles nicely. and when its full throttle the linkage is fully extended. is there another setting? Plugs are new. thanks in advance for the help.

 

[tater76]

Re: Force 125hp speed issue

Sounds like a trim issue, remember...when in doubt trim it out.

 

[Jiggz]

Re: Force 125hp speed issue

Sounds like a trim issue, remember...when in doubt trim it out.

I second this opinion also if it was just a speed issue. But with a 4200 RPM WOT it is more than just a trim issue unless the boat is heavily slicing into the water instead of planing.

 

[Jiggz]

Re: Force 125hp speed issue

What do you mean by, "when its full throttle the linkage is fully extended"? There are two things that matter the most with full throttle, the actual throttle valves in the carbs are at horizontal and the timing tower moved the trigger timing plate at maximum advance timing. When you move the throttle lever (after engaging the gear), these are the two things you are actually controlling, i.e. the position of the throttle valves and the position of the timing tower.

 

[Maine Fish Fan]

Re: Force 125hp speed issue

I second this opinion also if it was just a speed issue. But with a 4200 RPM WOT it is more than just a trim issue unless the boat is heavily slicing into the water instead of planing.

Thanks I will try to figure out why the trim drops. Could the system need to be bled? It goes up right away but drops as soon as I let off the button but I dont hear a pissing or leaking sound nor do I see ant fluid. and if it is just low on fluid I cant get anymore in the resvoire is full.

 

[Maine Fish Fan]

Re: Force 125hp speed issue

What do you mean by, "when its full throttle the linkage is fully extended"? There are two things that matter the most with full throttle, the actual throttle valves in the carbs are at horizontal and the timing tower moved the trigger timing plate at maximum advance timing. When you move the throttle lever (after engaging the gear), these are the two things you are actually controlling, i.e. the position of the throttle valves and the position of the timing tower.

Oh. Ok I know the the timing plate I have not checked that to see if it is full out I will check that now. thanks

 

[Jiggz]

Re: Force 125hp speed issue

You definitely need to bleed this unit when refilling. The problem if you put it into operation without bleeding, you'd be better off draining and bleeding it all the way again and then refilling it. The reason why is the fluid is now full of air bubbles and takes longer to let it stand and bleed it. Here's a general type instruction:

SYSTEM BLEEDING
1. Move the outboard to the full up position, and then tap the toggle
switch down just once to relieve excess pressure in the hydraulic lines. The
outboard unit must be in the full up position when checking or adding fluid
because the pistons are extended and the fluid level in the reservoir will be at
it highest.
2. Clean the area around the fill plug to prevent contaminants entering the
system when the plug is removed.
3. Remove the fill plug.
4. Check the fluid level in the reservoir. The fluid should reach the lower
edge of the fill opening.
5. Replenish the system using non detergent 30-weight automotive engine
oil.
Do not use automatic transmission fluid because such fluid contains
a high degree of detergent agents that could cause the internal seal
to prematurely wear and fail.
name oils should never be mixed, except in an emergency situation.
The complete system should then be drained at the first opportunity
and filled with only one name brand fluid.
6. With the fill plug removed, tilt the outboard up and down three to five
times to purge (bleed) trapped air from the hydraulic system. Bubbles will
appear at the fill opening.
Replenish the reservoir as necessary.
8. lnstall and tighten the fill plug.

 

[jerryjerry05]

Re: Force 125hp speed issue

This type needs to be DOWN.If it's a stock motor and no modifications to the Trim/Tilt???The 85/125 needs to be DOWN when adding fluid.
The newer Mercury ones might need to be up but the old Prestolite are down.
If you fill it while it's up,you can do damage to the unit.
You can force oil up into the electric motor and ruin the motor.
If the motor falls as soon as you let the switch off.Then the hydrolic motor needs repair/replace.
There are steps to test the hyd. motor.You have a manual?J

 

[Maine Fish Fan]

Re: Force 125hp speed issue

Thanks Jerry I dont have a manual but I have another motor I can put on it on a spare motor I will swap them out. While messing with the trim now it just stays on pumping up so I had to cut the wire so I have a few issues there. As for the timing lever on the tower that is full out when throttle is full out and just barely so that doesnt seem to be the issue. I had a 21 P prop I put on it and it would only go 18 to 20 and rpms at WOT were 2500. I am starting to think that it must need the trim working and a 17p prop that the 19p just does not work with the setup. Thanks for all the help. and gonna figure out timing as well.

 

[jerryjerry05]

Re: Force 125hp speed issue

Defiantly the trim must work to make the RPM's come up.
RRitt works on the Trim/Tilt hyd motors.

 

[Jiggz]

Re: Force 125hp speed issue

View attachment 154859This type needs to be DOWN.If it's a stock motor and no modifications to the Trim/Tilt???The 85/125 needs to be DOWN when adding fluid.
The newer Mercury ones might need to be up but the old Prestolite are down.
If you fill it while it's up,you can do damage to the unit.
You can force oil up into the electric motor and ruin the motor.
If the motor falls as soon as you let the switch off.Then the hydrolic motor needs repair/replace.
There are steps to test the hyd. motor.You have a manual?J

Jerry is absolutely correct if you are just filling in. But if you plan on bleeding the preceding steps apply.