Update on 1984 85hp force

[MKYxD]

New starter....starts right up. Idle was a little low. Adjusted that and good to go. However it skips and sputtered pretty bad but once your up 25mph or higher it's smooth. But tonight it got about 3 miles to the gallon. Seems horrendous to me. Ordered New plugs, going to use highest octane ethanol free I can get. Plugs in it all were sticky to the touch kind of like a tar type substance on them. Any suggestions or ideas?

 

[Jiggz]

Make sure the air fuel idle mixture screws are set at 1~ 1 1/4 out from lightly seated. There's no need to use higher octane gas. Instead, just make sure you do the correct mixture of 50:1. If you are not using NGK BUHW plugs yet, I highly recommend you switch. The BUHX are also acceptable but I recommend the BUHW with wider gap. Finally, do some decarboning.

 

[jerryjerry05]

3 miles to a gallon isn't that bad.
​I average 2.2-2.5

The skip and sputter is probably an air screw adjustment like Jiggz suggested.

Do a compression test and spark test.

The higher octane gas burns hotter and not good for the motor.
These were designed to run on regular pump gas.

 

[MKYxD]

So whats better 89 octane with 10% ethanol or 91 octane ethanol free. Those are the options at my gas station

 

[Jiggz]

If you can afford the 91 ethanol free is better for the fuel system. I doubt it is better for engine running. I've used 89-10 eversince and never had any fuel related problem, so far. And as far as 2 cycle oil, I used the cheapest I can get my hands on, usually from WM!

 

[MKYxD]

Boat also pulls hard right. And is hard to turb wheel left when driving. Internet says adjust trim tab....this motor does not have one.. Howevee the exhaust is where trim tab belongs. Is it ok to turn the exhaust ? Im asuming its like a 2 in 1 deal but functions the same

 

[SkiDad]

Boat also pulls hard right. And is hard to turb wheel left when driving. Internet says adjust trim tab....this motor does not have one.. Howevee the exhaust is where trim tab belongs. Is it ok to turn the exhaust ? Im asuming its like a 2 in 1 deal but functions the same

yes the exhaust snout acts at trim tab - loosen rear bolt on exhaust snout and move rear to the left and tighten. I have mine all the way left but you might find a happy medium somewhere between left and center.

 

[jerryjerry05]

From the back of the boat looking forward.
​If the boat turns left turn the snout to the left..

 

[MKYxD]

my boats pulling right. so does the rear of the snout face to the right or the front of the snout face right? Also invested in some NGK plugs as they seem better in 2 strokes than champions in my experience. Maybe not on boats but we will see.

Also cleaned some junk out of fuel filter, was a fair amount in there but not sure it was enough to cause rough running.

 

[Jiggz]

If boat pulls to the right or stbd, then the rear of the exhaust snout or the so called trim tab should be adjusted facing to the left or port side. Or if you want to reference the front of the trim tab, then it should be adjusted to face to the right or stbd side.

 

[MKYxD]

Thank you willl adjust accordingly

 

[MKYxD]

So new plugs and seafoam and she is idling like a dream and running smooth as ever up to 3/4 throttle. Now when you go fukl boar it bogs/pulses and will die if you dont pull back throttle. So the skipping mid range and rough idle have been cured. But it used to run wide open no problems...so not sure why syptoms have changed

 

[Jiggz]

An engine idling and running smooth only up to 3/4 throttle but starts to misfire thereafter is usually caused by improper timing. It is most likely the timing is set too far advance hence when placed in full throttle it starts to misfire. The only other thing I can think off besides timing is a bare wire from the trigger rubbing against ground when in full throttle position.

Verify timing first. If it is correct, then you might want to look under the flywheel and check on the trigger wires. You don't have to remove the flywheel for now instead measure resistance on each set of wires to ground while moving the throttle to full forward and neutral. There should be no continuity between each trigger wire and ground.

 

[jerryjerry05]

Sounds like a fuel delivery problem now??

 

[MKYxD]

Well cleaned bowls had some crap in them. Bad part is i broke a main jet. F10173 part number and they are no longer made gonna probe net and call marinas to see if they have scraps laying around. Hate to lose a motor because i ruined a 10 dollar part

 

[jerryjerry05]

E-bay you might have to buy a carb?
​Just make sure the jet's the same.

 

[MKYxD]

I read on a thread several years old there was a jet that is exact fit except you have to drill the holes larger to the .074 they didnt give a part number unfortunatly

 

[Jiggz]

You probably have a better chance of getting an whole carb than just the jets. Of course, it'll cost a lot more.

 

[jerryjerry05]

E-bay has a set for 70$

 

[jrenneker]

Ok funny thing is I broke the same bolt.. MKYXD did you ever find one? Man how frustrating. One part can cause so many problems.