85 Force 125 - how am i looking / suggestions

[SkiDad]

I recently got an 1985 Bayliner 1900 with a 1985 Force 125hp. It has the original 17p prop from day one - no dings or anything - the guy was meticulous about caring for this boat.

anyhow, I'm running WOT about 4400 RPM with 2 guys on board and about 12 gallons of gas. GPS is showing 38. Idles right at 750 in gear, and has smooth take off, just not sure why it's not hitting more rpm. I'm familiar with this engine, My dad has an 88 Cobra 18' with the 125 as well but his is turning about 5500 with a 15 pitch michigan wheel prop and 4 people on board - had it out lots of times.

the plate says I should be 4500-5500 - am I OK running at 4400 ? I'm wondering if I need to just run the boat for a while and it will open up some more.

I made some notes while driving - 3000 RPM is 25 MPH GPS / 3500 is 29/30 MPH GPS / 4000 is 35 MPH GPS (so the tach seems to be about right to me)

 

[pnwboat]

Re: 85 Force 125 - how am i looking / suggestions

I think you're just about in the ball park as far as RPM's and speed, but it really depends on the hull design, weight etc. I'm not 100% sure, but I think you should be turning a little closer to 5000 RPM's with your set up. You might want to check a couple of things out with the motor if you haven't already done so. Like compression, and verify that the carburetor throttle plates are all the way open (perfectly horizontal) when you push the throttle all the way forward.

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

my hull is about 1250 / motor is about 300 / figure 200 for battery/fuel / 100 for junk / 450 for 2 guys /

so I'm thinking 2300 lbs

my hull is the sequential lift hull / but it is a deep V

do I check the throttle plates with engine off ?

 

[pnwboat]

Re: 85 Force 125 - how am i looking / suggestions

With that weight and hull design, you're probably close to maximum performance. Make sure the motor is trimmed up so it will allow more of the bow to come out of the water and reduce drag. Yes you want to check the throttle plates with the motor shut off. Push the throttle all the way forward (make sure it stays in position) and walk back and check'em out. They should be perfectly horizontal.

 

[Jiggz]

Re: 85 Force 125 - how am i looking / suggestions

I recommend viewing the position of the throttle valves (butterflies) at WOT setting (of the throttle control) don't have to run the engine. They should be on the horizontal no more no less. Adjust if required using the linkage bar.

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

thanks for the responses - if it is not open all the way how do I adjust ?

 

[Fishing4Walleyes]

Re: 85 Force 125 - how am i looking / suggestions

I had one those except it was a 1986 model. I forget most of the things about it but 35-40 was the most I could get out of it.

 

[Jiggz]

Re: 85 Force 125 - how am i looking / suggestions

thanks for the responses - if it is not open all the way how do I adjust ?

Item #35 is the bar assembly that connects the two carbs but is also adjustable. And then you also have item #42 which can also be adjusted.

http://www.crowleymarine.com/mercury-outboard/parts/1215_4.cfm

 

[jerryjerry05]

Re: 85 Force 125 - how am i looking / suggestions

Do a compression/spark test.
Post your results.
That ok,top post in the Force forum.
There is a link by FrankA. Linc and sinc do this.See if it 's ok.
That boat should do about 35-40

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

OK - i finally had a chance to test the compression today. all 4 showing between 150 and 155

I did a spark test on an earlier date and they have have a nice spark on all 4.

my butterflys are just about perfectly strait open at full throttle.

one thing I did the other day was adjust my mixture. I set them to 1 & 1/4 out. PO has set top at 2/3 out and bottom at 3/4 out - no idea why. As soon as I did that the thing idled so much better seemed to take off a tad smoother - but no change on top speed.

But even with the fuel mixture adjustment I'm getting 4200 rpm with 4 people on board and about 4500 with 2 people on board. I still think I should be hitting 5 grand with this prop.

thoughts ? and thanks so much for all the help

 

[jerryjerry05]

Re: 85 Force 125 - how am i looking / suggestions

Go for a ride.Take the cover off.
Get it going full tilt.
Then have someone push the throttle all the way.Make sure the linkage can go all the way.
Check the timing advance linkage.
You sure the prop is a 17
Next get another tach and see if it's really doing 4400
On the back of the tach is a tiny black arrow with a screw slot(very tiny)try turning this.Remember where you started,so it can be put back.The connections should be tight.Check the ignition and replace any suspect connectors.
I just went through and replaced all the connectors on my motors.Some were vey shakey???
My tachs don't always read right.
I have a Tiny Tach as a back up it work great.
Set the air screws at 1 turn out.
To set the air screw,warm motor,then turn in till it bucks,stalls,stutters or quits.
Then out 1/2 turn.Then do the other carb and then do it again.
Check the inline connectors,they can go bad and suck air.I remove them and put in staright hose.

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

you know I took a boat trip with the family Tues and i had to turn the idle up b/c I had adjusted the carbs some the other day. Anyhow, I fired it up and took a spin with cover off and it hit 4700 with everyone on board - hit 41 gps. I was actually shocked. I did do a quick decarb with a 1/2 can of seafoam aresol but also slightly adjusted the linkage to make sure they were dead flat a few days prior.

Then I put the cover on and it still did 4500 with everyone on board - which is about 2-300 better than normal. Not sure if the 4700 was a fluke or having the cover off did something. I'm betting the hoses are original - they don't look bad though - but maybe i'm sucking some air.

i did go through all my electrical connections when I changed the stator last months.

the cam hits the roller all the way when i push the throttle all the way. I didn't have a chance to try having someone push it more while driving. I can't seem to get the mark on the cam to line up well with my new air mixture... when I turned the air mixure to more rich it lowered the idle so i had to turn about 1.5 turns on the idle screw to get the right speed but the cam marks are just a little past the top mark.

one other thing I haven't gotten straitened out is that the idle is a different speed each time I accelerate and stop - sometimes it will neutral at 1100 sometimes 1400 or anywhere in between- seems odd to me -but maybe it's normal. the setting i had it is about the lowest I can go or it will stall in gear (about 800 in gear)

also, it usually will not start the 1st turn when warm with the throttle strait up - it will always start it put in it the warm up position.

which connector is the inline one ?

 

[jerryjerry05]

Re: 85 Force 125 - how am i looking / suggestions



Any connector that's inline.See pic these are famous for leaking.
If your loading the boat with the "family" it could possibly be too heavy to get the top rpms.
1-2 people,cooler,1/2 tank of gas go for a ride.See what your rpms are.
You might have to change props.
You sure what the pitch is?

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

i spun the hub in my propeller the other day so i was forced to get a new prop (was going to do it over the winter) well i'm positive the original prop is 17 - checked all the numbers and it has the original finish on it etc.

anyhow, good news is I picked up a new 15 pitch michigan wheel (072055) and my rpm went up 600 rpm. Typically I was about 4500 with the family aboard - today I hit 5100 consistently. Speed was about 38 MPH. Seems to be in the right RPM now and that everything is running the way it should. So I'm thinking that is all she wrote.

mixture screws are at 7/8 out and seems to run the best there.

thanks for all the helpful hints !

 

[emoney]

Re: 85 Force 125 - how am i looking / suggestions

That sounds better. Probably better off that the hub did get spun since it sounds like the old prop was lugging the motor a smidge. Happy boating and thanks for the "it's fixed" update.

 

[jerryjerry05]

Re: 85 Force 125 - how am i looking / suggestions

The setting?
From lightly seated out 1 turn.
Then after it's warm.
Turn in till it coughs,bucks,misses.
Then back out 1/2 turn.
You can do damage to the pistons if it's into far or out too far.

These motors weren't made to idle or idle good.
They're made to run fast!!.
The air/fuel mix is only for running at idle.
Doesn't really do anything for running above an idle.

The factory says to open to 1 full turn out and leave it there.
That's how I set mine.
I've tested my motors and it seems the air screws end out about 1 turn either way.

 

[SkiDad]

Re: 85 Force 125 - how am i looking / suggestions

thank you