1975 20HP Johnson Starts at full throtle

[mello__yello]

Hey - I just bought a boat and I have the time to tinker but just need some direction. I have a service manual for the motor as well. But I have never owned an outboard and my mechanical experience is somewhat limited - but I am a good learner.

I have the motor set in a barrel of water and it cranks on the first pull - but it is revving very high - pretty much at full throtle. I tried 8 turns on the screw to make it less rich but it seemed to make no difference at all.

When I have the engine off and put it into gear and move the throttle lower and place it back into neutral it puts it back to where it was.

Any help is greatly appreciated.

Thanks,

Andrew

 

[mello__yello]

Re: 1975 20HP Johnson Starts at full throtle

Sorry - a little more info - The guy I bought it off had it running last summer and advertised it ready to launch, it was stored indoors for the winter - I am running a 40-1 mix.

 

[Pony]

Re: 1975 20HP Johnson Starts at full throtle

For starters, though 40:1 wont hurt anything, you should run it at 50:1.

I will leave the rest up to the experts.

 

[BoatBuoy]

Re: 1975 20HP Johnson Starts at full throtle

From what I see, Johnson didn't make a 20hp in '75. Could you give the model number, located on a metal tag somewhere on the stern bracket or steering bracket.

 

[mello__yello]

Re: 1975 20HP Johnson Starts at full throtle

Model Number 20BA 75B

 

[whywhyzed]

Re: 1975 20HP Johnson Starts at full throtle

I have a 75 Evinrude 20 that also supposedly doesn't exist. A lot of 20's were sold in Canada but most service literature does not typically acknowledge them.

As far as revving high, just watch the linkage carefully going to the carb- see the 2 links that are connected with a little "bridge" and a bolt? follow those with your eye and watch as you twist the throttle to make sure everyhting moves with the throttle both directions.... watch that the throttle plate linkage is closing like it should.

The throttle should actually be limited by the linkage in neutral. When you put the F/R lever in gear, you should see that there is much more throttle movement.

A thorough decarbing with sea-foam is not a bad idea.

 

[mello__yello]

Re: 1975 20HP Johnson Starts at full throtle

Ok - I brought it to the shop - because Iam on holidays starting friday an they are fixing everything for me for $250 with that - they tell me it will be like a new motor - and thats awesome

But I still want to make this a project in the winter - does anybody recommend a manual/book that covers this motor (that supposedly doesn't exist) That will help me from the ground up... I am a very intelligent guy - I just need direction when it comes to automotive.