72 Johnson 50 fuel problem

[2Johnson50]

My 1972 50hp Johnson wont start with the engine cover on. If I remove the cover it will start and run but not very smoothly. The only thing I can think is that its running too rich with the restricted air intake with the cover on but get more air when its off. Does anybody have any ideas? My carb jets arent the standard tapered kind but are blunt on the end. I have been told that there is no carb adjustment but that doesnt make sense since the is access to the jets without removing the carbs. Are they talking about high speed adjustment or idle adjustment and not rich/lean adjustment? Any ideas would be appreciated. Thanks.

 

[racerone]

Facts-------We must first establish what you have here.-----It is possible that you motor does not have the original carburetors.---The original carburetors had tapered needles for low speed mixtures.----Also after 40 years I can not imagine that the motor cover can now cause an issue !!--------Post picture of your " blunt needle " so we can be of further assistance.

 

[boobie]

Agree, post some pics.

 

[racerone]

No reply , so here goes.---You have newer carburetors with fixed low speed jets.---What you think are " adjustable jets " are merely a plug that should be screwed in tight.-----Look at say a late 70's 2 cylinder 55 /60 hp carburetor parts breakdown.--Somebody fitted those carburetors to get a free power boost.

 

[2Johnson50]

To elaborate, I bought the motor used. It didnt run. I finally figured out that the flywheel drift key was sheared and of course timing was way out. Fixed that. Took it to the lake and it ran for awhile but continually got harder to start and finally quite completely. Have rebuilt the carbs.

You're right the the jets seem to be similar to that of a 78/79. Dont have a manual for that so do you know if these these jet that just look like a bolt but smooth on the end are just tightened or do they need to be adjusted in or out?

Any other ideas why it starts initially only with the cover off. Once it starts and is warm it will run with or without the cover. thanks.

 

[boobie]

I think you're talking about the float bowl drain screws.The high speed jets are under them in the float bowl and they're non-adjustable.

 

[racerone]

I will repeat -------It is not an adjustable jet, it is a plug.--The fixed low speed jet is visible way inside of that plug.