Top speed??

[jitterbug127]

I recently bought a 1983 Johnson 15 hp outboard. It functions as it should. Compression is 105/105. Has strong spark that will jump a 3/8" gap all day. I took it out fishing all day Saturday. Motor did not disappoint. My only concern was the lack of speed. I was getting 13 MPH max out of the motor with only me in the boat.

I had almost same motor last year (1990 15 Hp, rope start only, compression 96/100) I could get 19-20 mph out of. I put the 1983 stern bracket on the second lowest setting which is where I had optimal speed on my 1990. I also have the same 9.5x10 pitch prop on both motors.

My boat is a 1980 smoker craft 16 x 54 flat bottom Jon boat. Any idea what I should expect as a max speed?

PS...My 25 isn't running right, so I am left with the 15 for the time.

 

[Crosbyman]

same RPM ? same 2-3 blades boat weight same shape ...etc....

 

[jitterbug127]

same RPM ? same 2-3 blades boat weight same shape .

Same boat, same 3 blade prop style. I’ve not checked rpm. Didn’t cross my mind. I have a tach I bought never used it

 

[jitterbug127]

Here she is running.

 

[flyingscott]

Sounds like it is running on 1 cylinder

 

[saltchuckmatt]

5 less HP.....two dudes, one cylinder?, wrong prop, spun hub, muddy water, barnacles on boat hull, going up river, cought to many fish..... It's endless.

 

[saltchuckmatt]

Boat + HP does not equal the same prop pitch.

 

[jitterbug127]

5 less HP.....two dudes, one cylinder?, wrong prop, spun hub, muddy water, barnacles on boat hull, going up river, cought to many fish..... It's endless.

Same hp motor. 1983 15 vs 1990 15. And we definitely didn’t catch too many fish, sounds like a pleasant problem to have though!!

 

[jitterbug127]

Sounds like it is running on 1 cylinder

Every motor video I’ve ever shot someone has said that. I must have a crap phone. 100% running both cylinders.

 

[saltchuckmatt]

I must have been tired ...could have sworn it said 9.9

You must have edited it, I'm NEVER wrong!

The "caught to many fish" you should have gone with that. Hehehehe.

Transom/outboard length?

If not than I would start fishing for the Loch Ness monster!

 

[saltchuckmatt]

Just watched the vid again, always 3 in the boat? Did you try shifting weight?

That's a lot of lard!

 

[flyingscott]

Is the carb opening all the way? Roller in good shape? None of the throttle bits are broke?

 

[jitterbug127]

Is the carb opening all the way? Roller in good shape? None of the throttle bits are broke?

Carb open all the way. Roller is in good shape, no broken bits on the throttle.

I cleaned my carb and turned the screw on the cam roller just a 1/8th of a turn or so. Unfortunately the low speed idle adjustment on the side seems to be stiff. I'm going to lubricate it and see if I can free it up.

I am hook motor up to a tach on the river as soon as I get a chance make sure she's reaching the proper RPM.

 

[jitterbug127]

I must have been tired ...could have sworn it said 9.9

You must have edited it, I'm NEVER wrong!

The "caught to many fish" you should have gone with that. Hehehehe.

Transom/outboard length?

If not than I would start fishing for the Loch Ness monster!

If motor is 9.9 OMC is doing some false advertising.

Transom length is 20". This is long shaft so 22".

I don't think I've ever caught too many fish. Hope my next trip out is the day!

 

[jitterbug127]

Just watched the vid again, always 3 in the boat? Did you try shifting weight?

That's a lot of lard!

My speed assessments are based on 1 in the boat. I was getting 13.5 mph out of this 15 with just me in it. I was getting around 8 with 3 dudes in the boat. Brett must've had that last bagel that morning and was slowing us down.

 

[saltchuckmatt]

Over and over again, I always hear someone complaining about a guy named Brett!

 

[Crosbyman]

Brett from the french word "bretter" pronouced "brettay"

... which means hesitating .. not completing a task ... waisting time

 

[jitterbug127]

I slapped this motor on moms boat since she needed electric start and called it a day. Her house has a couple acre pond and they might get it on big water 2 times this years.

 

[saltchuckmatt]

I slapped this motor on moms boat since she needed electric start and called it a day. Her house has a couple acre pond and they might get it on big water 2 times this years.

Perfect.

Lifejacket?

 

[jitterbug127]

Perfect.

Lifejacket?

I don't have the slightest clue.