1989 Force 50 only goes 10mph

[Bodaggit23]

Hello everyone, first thread, second post for me here.

My Dad gave me his boat.
He bought the boat at age 78 and never
noticed this issue because he likes to putt
around and fish and doesn't care that the
boat won't plane out.

I want to pull kids on tubes and skis with it
but it won't go faster than 10mph via GPS.
It starts great, seems to run perfect, doesn't stall, etc.

I don't have a tach but I can tell it's not revving
anywhere near the 50rpm where range that it's supposed to.

This video is an attempt to "de-carbonize" the motor.
(One gallon gas, 3 ounces oil, 16 ounces Seafoam)

I'll post another video of the boat in action in a day or two.

Thanks in advance for any help.

 

[procraftguy]

Re: 1989 Force 50 only goes 10mph

Check at full throttle moter off that carb butterfly is wde open then also check timming advance is moving forward and tight no broken streched conecter (under flywheel above your fuel filter i can see )it wouldnt let me watch video if that all checks out compresion test could be one cylinder bad rings

 

[jerryjerry05]

Re: 1989 Force 50 only goes 10mph

Like procraft suggested a comp test and then a spark test.
Plugs burning OK?
If it's revving up and no speed? Possible spun hub in the prop?

 

[Bodaggit23]

Re: 1989 Force 50 only goes 10mph

Thanks for the replies guys!

Check at full throttle moter off that carb butterfly is wde open then also check timming advance is moving forward and tight no broken streched conecter (under flywheel above your fuel filter i can see )it wouldnt let me watch video if that all checks out compresion test could be one cylinder bad rings

I checked the carb butterfly (inner one, closest to reeds)
and at full throttle, it is fully horizontal, or wide open.

The timing advance linkage is moving smoothly along
with throttle linkage input throughout entire range.
Nothing appears broken, loose, or stretched.

With my handy dandy $20 HF Special compression tester I'm
getting about 105 psi on both cylinders, they're exactly the same.

Like procraft suggested a comp test and then a spark test.
Plugs burning OK?
If it's revving up and no speed? Possible spun hub in the prop?

Should I do a spark test like you would on any other small engine?
Meaning take the plug out, snap it back into the wire and rest the threads
on the head and turn the ignition?
It seems to have good spark I guess, it starts, runs, and never dies. ?
Is there another way to test spark?

I don't think the motor is revving as high as it should, maybe half as high
but that's just a guess. The prop seems fine, I put it in gear and turn it and
it just turns the motor over, doesn't slip at all.?

Before the "de-carbonizing" cycle the plugs did seem to get some blackish
buildup on them after it's ran. Me and my boys are taking it out in a couple
hours to attempt to pull a tube around. I'll post pics of the plugs when we
get back, along with a video of the motor running wide open so you can hear
how high it's revving.

Again, my sincerest thanks for any help!

 

[Bodaggit23]

Re: 1989 Force 50 only goes 10mph

I guess "de-carbonizing" worked!

I got it up to 22mph yesterday! Woohoo!

I think I'll try one more round of "de-carbonizing" and
see if I can't get a few more rpm's out of it.

Anyone think it's as good as it will get because of my compression?