Lack of Power 1989 50 HP

[mytmouse]

507Y9B
I am hearing the "clank" perfectly when it engages and I go into reverse, but in forward I am not hearing it or feeling it engage. I can travel about 7 miles an hour (at WOT it revs way higher than the boat is going) In Fact I think my prop is spinning when I am in neutral. Is this a control to motor adjustment, or is it a motor to lower end adjustment? After being on river today, couldnt get above 7 miles an hour, pulled back to neutral, then wot again and then it "caught" and I was able to run normally. any tips appreciated.

Scratch the not hearing clank, It definitely goes into gear. see my detailed reply to issues please.

 

[steelespike]

Re: Not hearing engaged sound when shifting 1989 50 HP

Re: Not hearing engaged sound when shifting 1989 50 HP

The clutch dog is either ingaged or not ingaged there is no in between.Most likely the high rpm and low speed is
a spun hub on the prop. Easy to check.Remove the prop and mark across the hub under side of the prop with a permanent marker.Run the motor and check the mark. It is normal for the prop to turn in neutral.

 

[mytmouse]

Re: Not hearing engaged sound when shifting 1989 50 HP

Re: Not hearing engaged sound when shifting 1989 50 HP

Thanks steel. Just took it to water to try all 4 props that I have (why didnt I read this prior to doing that??)....all 4 same result. Here is what I can say for sure.
507Y9B
Fuel pump overhaul (gasket, diaphram, filter)
Carb overhaul, replaced with new parts on all that was in kit
Lower End Re-Seal, (no leaks), driveshaft and prop shaft turn smmothly before and after reassembly.
I am getting the cam dog to engage for sure as it is going both forward and reverse.
Powerhead was removed by local shop to re-install copper water tube. I am just getting the boat back and this is the new problem, although it is blowing water like a banshee now.

My questions are:
Could this be as simple as plugs?
Could my carb overhaul affect this? When doing the overhaul I replaced all parts that were in the kit that I could with new. When I reassembled then brought to shop I forgot to set the Idle needle at one turn back out from just seated (thats right isn't it?) It was set at about 6 turns out from just seated.....hence why I am now thinking plugs????

Same with fuel pump overhaul?
Should i mark the prop before asking these questions?
Can the prop be marked and just run in a tub, or do i need to go under load in river?

Any ideas?
1 prop I just bought, is new surplus, shiny new...it is one that as on boat when I took to shop for water tube reinstallation.

I have 130+ compression in both, fires right up, runs beautiful....i just cant gather speed....It seems to run ok at 1-5 mph, but when I get on it a little this is when I cant accelerate...engine outrevs the performance I am getting.

is it possible I dont know how to drive a boat and maybe I need to go WOT then back off to desired speed?
Not sure if I am creating cavitation, but thought crossing my mind now as I am home. I guess I slowly accelerate like a car.

 

[steelespike]

Re: Lack of Power 1989 50 HP

What is happening is very unlikely to be anything except ventilation.
Has this motor ever performed on this boat?It appears your props are ok.I don't think it is necessary to mark and check.It seems that you may be expierencing ventilation (cavitation is different)The motor may be too high or possibly a short shaft (15 inches)on a boat made for a long shaft (20inches).The antivent plate just above the prop should be approximately even with the bottom of the boat.Measure and let us know what you find.

 

[mytmouse]

Re: Lack of Power 1989 50 HP

Has this motor ever performed on this boat?
Yes, used around 10 times (bought in February), only initial problem was lack of proper cooling due to copper tube being out.

Original Force 50 on 1989 Blue Fin Spectrum 1700 (16.6 feet).

Am going to measure this morning and will post shortly the measurement from ground to bottom of boat, and ground to antivent plate.

If I am not mistaken, there are 4 additional holes on the transom from where the motor at one time sat. As soon as you typed possibly too short of shaft....my mind starts thinking if possibly he mounted the motor (after copper tube repair) in the wrong holes??? Will advise of findings.

 

[mytmouse]

Re: Lack of Power 1989 50 HP

When motor tilted all the way down 16 1/4" from ground to antivent plate.
When motor hits first "stop" on way down it is 18" from ground to antivent plate.
Bottom of boat is 18" from ground.

I have been running it in the 16 1/4" I believe.

 

[steelespike]

Re: Lack of Power 1989 50 HP


I don't think your method is very accurate.But with the ventilation problem it may be too high.You may want to lower it a hole.Or trim in just see if it helps.
If you want to measure the transom
you need to measure from the transom top where the engine rests to the bottom of the boat. should be close to 15 inches for a short transom and close to 20 inches for a tall transom.If the transom has a lot of rake you may need to measure the actual verticle distance instead of along the transom.But more importantly initially the anti vent plate should be about even with the bottom of the boat. And the plate should be parallel with the bottom at that starting point.Then after testing final height and trim can be fine tuned.You may have to use a straight edge along the bottom to see better where the plate is.

 

[mytmouse]

Re: Lack of Power 1989 50 HP

"is it possible I dont know how to drive a boat and maybe I need to go WOT then back off to desired speed? "

YESSSSS

WOT = no performance probs, motor working fine!! Thanks all