My new force

[Justinde]

HI all

I am yet to pick up my new boat, but it has a 125hp Force in a circa 1988 model ( can confirm later), but I took it for a drive and wide open throttle was 3500 rpm and an indicated 35mph. The boat is a 17ft force custom bowrider. The seller has recent reciepts for pretty much a complete engine rebuild ($4500AUD) for new powerhead, new pistons/rebore, new seals gaskets etc, new gearbox, new plugs, new steering system, and new electrics inc ignition etc. The seller has 2 props, and I am going to fit the other prop to see if it makes difference, however, I have 2 questions.

1: How can I tell the pitch of a prop- is it stamped somewhere?
2: If it is NOT the prop, and considering the amount of work already done on the engine, any ideas as to what it could be?

I'll look for the right post to put some pics up.

Cheers

 

[Justinde]

Re: My new force

Sorry, but I might as well show you all some pics here!!

http://i53.tinypic.com/2upwuus.jpg

http://i56.tinypic.com/4kz9rp.jpg

http://i52.tinypic.com/2lkz0ar.jpg

 

[pnwboat]

Re: My new force

3500 RPM at wide open throttle is below the minimum operating speed for a 1988 125HP motor. Operating range should be between 4500 - 5500 RPM's. It may be over propped ( too high of a pitch on the blades). Also make sure the throttle plates on the carbs are opening all the way.

The propeller pitch is usually stamped or cast into the hub of the propeller. Sometimes the washer underneath the nut that holds the propeller on obscures the numbers. For example 13 1/4 X 17 would indicate a 13 1/4 inch diameter, 17 pitch blade. I suspect that you may have a 21 pitch prop. This would explain the low RPM. A 17 pitch prop would probably be more suited for your set up.

Nice clean looking boat! The white horizontal fins mounted on the cavitation plate can also decrease top end speed. Depends on the boat. I originally had a set on mine when I first purchased it. Rode very smooth through rough water, but decreased top end speed by 3 or 4 MPH. I took them off. Some folks report no decrease in top end, so again, it kind of depends on the boat.

 

[Justinde]

Re: My new force

Thanks pnwboat.

I was thinking of removing the fins, and you have confirmed what I was intending! About the prop, the seller said one was Stainless Steel, and one was Alloy, but they didn't know which was which, nor what they were for. When I get her in the water again, it will be with the alternate prop, and I'll report back.

Thanks for your comments, it really is a tidy unit, considering its age! I am hoping I can get around the 40mph mark when correctly propped!

I'll keep you posted.

Cheers

 

[Justinde]

Re: My new force

PS- sorry Bob. First time posting pics!!

 

[pnwboat]

Re: My new force

Should be fairly easy to determine the stainless steel from the alloy prop. Stainless steel is heavier than the alloy which is usually an aluminum alloy.

 

[NYBo]

Re: My new force

Welcome to iboats!

The prop mounted to the motor in the picture you posted is aluminum, based on the fact that it's painted. Stainless steel props aren't usually painted.

 

[jerryjerry05]

Re: My new force

1st thing in buying any boat.A COMPRESSION and SPARK test.
The props are of little concern if the motor isin't right.
3500 rpm is 2000 below specs.
Even if he has reciepts that say it was rebuilt last week do a compression test.
The props should have #s stammped in them somewhere.The black Force props should have #s on the side somewhere.
Not all stainless props are shiny.Johnson/OMC/Yamaha all have painted stainless props.But Force stainless is usually shiny.
Do the comp and spark test and get back to us.J

 

[Justinde]

Re: My new force

Will do- thanks for the help guys. With the comp test- do I need to know anything, or just remove one plug at a time? All plugs then test cylinder by cylinder? And with the spark test, do I just remove a plug, put the lead on, and ground the sparkplug, or are there electrical things that can go bang if I do the wrong thing?

 

[jerryjerry05]

Re: My new force

Testing the compression.Remove the plugs.Then install the tester.Turn the motor over till the comp stops going up.Do each cylinder.
They should be within 5-10# of each other.
Get a good plug puller Amazon.com Lisle 51750 Adjustable Spark Plug Wire Puller.Something like this.
Start the motor and pull each plug.It should make a difference in the sound and way the motor runs.Or key in spark tester and it will show all kinds of in-line testers.
After the comp and spark check OK.Then you can work on the props.You check them for numbers?J

 

[Justinde]

Re: My new force

Hey Jerry

I'll check it when I get it. I am yet to pick it up, but I will post the comp results when I do.

Thanks for your help guys, catch you soon with some results!

 

[Justinde]

Re: My new force

HI All

I picked up the boat and cleaned the stainless steel prop- and the only stamp I can find is " P509". What does this mean?

CHeers

 

[jerryjerry05]

Re: My new force

P 509 Is the part# If you contact Michigan Propeller they can tell you what size prop you have.J