Smokey - 1980 Johnson 4.5 HP

[tpenfield]

Update:

I got a fuel filter and made a new fuel line, since the old one was not in great shape.



I got it installed and ran the engine for a while. I also blocked off the pulse tube, so the bladder pump would be inactive. The engine seemed to run better and I can lean it out a bit.



Overall, the engine seems to like a rich mixture as it tends to fade when I try to lean it out. It is still a bit smokey, but not quite as bad.

The engine seems fairly hard to start once it is warm and I stall it or just shut it down. It seems to like choke and the throttle all the way to idle. . . it probably can suck fuel out of the carb jets better that way. I'll just have to see how reliable it is when put into use.

My 1969 Mercury has been bullet proof . . . not sure this engine will be as good. :noidea:

 

[tpenfield]

double post

 

[racerone]

????----That engine first came out in about 1953 and was around with improvements for over 30 years.--My opinion says it is a good simple design.

 

[tpenfield]

????----That engine first came out in about 1953 and was around with improvements for over 30 years.--My opinion says it is a good simple design.

No doubt, I just feel like there is still something wrong with it, that is making it finicky, but I am not sure what.

 

[tpenfield]

Update:

I have not run this engine much at all this year, since the sailboat that I am going to use it on is in restoration mode in my garage. Anyway, I did a couple of rounds of 'de-carboning' using the Mercury Power Tune instead of SeaFoam and the engine seems to run a lot smoother. It still is smokey compared to my Merc 7.5, but it runs fine.

One thing I noticed is that the fuel mixture adjustment knob that is on the front panel of the cowling is titled "Slow Speed Adjustment". So, is that to mean that when you are going at slower speeds you will want/need to manually adjust the mixture??? :noidea: Just seems odd that would be the prescribed method of a 1980 motor.

My Merc 7.5 HP does not have such a thing, rather has fuel mixture screws that you set and forget. . . .

The Johnson seems to run fine without messing with the mixture screw, so I think I will just leave it that way.

 

[racerone]

Not sure why you think that is odd at all.------The high speed mixture is not adjustable.--------The low speed mixture is adjustable without taking the cowling off and finding a screwdriver like you would for the Mercury.------Low speed mixture needs tuning depending on fuel and local atmospheric conditions.-------These 2 cylinder Johnson motors are simply GREAT motors.

 

[tpenfield]

I guess the only thing that I am finding odd is that the engine seems to like a different mixture at slower speeds, which may be a unique situation for my motor.

 

[racerone]

Are you adjusting the slow speed mixture at full throttle ??-----If so then yes you will need to adjust that when you go to an idle !-------This carburetor has a fixed high speed jet and no adjustment is needed at full throttle if motor is in good condition.-------Once slow speed mixture is set at idle it will rarely need adjusting again same as the Mercury you have referred to.-----------If not so , then there is something wrong with the motor.

 

[tpenfield]

I'm just finding that the mixture likes a bit of adjustment at lower speeds versus what it likes at mid-range and higher speeds. It still runs without adjustment, so it is fine. I just wondered if Johnson made the idle adjustment accessible for more than just convenience

 

[jakedaawg]

The low speed adjustment is just that, an adjustment for idle in gear. Set it and forget it if nothing else changes. You do not adjust it at all if at more than slow speed. I think this is covered in the sticky up top. Easier to read the well laid out directions than for someone to rype them in this thread.

 

[jakedaawg]

As far as the excessive smokeing, have you been able to run this under laod at temp? It may just be excess fogging oil in the exhaust. If someone really fogged it good for long term storage it can take awihle for little ones to get warm enough to burn it all out.

 

[tpenfield]

I'll have a chance to run it on the dinghy next weekend to see how it goes.

 

[tpenfield]

Update:

I was able to run the engine on my dinghy today, since the sun finally came out. It runs fine . . . all throttle positions seem to run well, no need for adjustment.

Here is a video that I made running the engine through the throttle range and back down.

The engine is certainly running better this than it did last year. I think the de-carbing helped. I don't really notice excess smoke when it is under load. So, all is good.

 

[tpenfield]

Quick Update:

Now that I have the engine running fairly well, I decided to re-paint it and put new decals on it.

The paint did not quite match the decals, but it looks 100% better than before.

Here is the re-paint






Here are the decals.













I think the 'Johnson White' was not the proper color, should be a bit brighter, but it is fine.

So, once my sailboat restoration is done, I have a motor for it

 

[jasper60103]

Nice make over to old smokey.
Good runner too.

 

[tpenfield]

Nice make over to old smokey.
Good runner too.

Thanks