70 Johnson Carb rebuild

[Steele329]

I bought my boat last season and have been running the hell out of it ... Having a blast but I think it may be time to start giving back. Other than basic tuning I have not done any major work and given the age and condition I think Its time (She runs like a champ!) I noticed a small fuel leak (from the air box) after boating then trailering and after reading some forums I'm thinking its time for a carb rebuild or at the very least a cleaning. I just need some straight forward advice. Having no experience marine wise (i do have engine and compressor experience) should I attempt myself or pay? What am I looking at? Is this as easy as some make it to be or not? Any pointers? Help me if you can thanks! 1977 70 Johnson 2 stroke 3 cyl.

 

[Boss Hawg]

Re: 70 Johnson Carb rebuild

Only advice I can give it its running great why rebuild the carbs?
Unless you have down time & bored or have nothing else to do leave well enuff alone-
Fix the fuel leak tho----------

 

[Steele329]

Re: 70 Johnson Carb rebuild

The fuel leak is what got me thinking. After reading other posts people were saying that its caused by carbs leaking back and that replacing the air box gasket did not fix this. Maybe I should try that first before I get all nuts with it?

 

[JDusza]

Re: 70 Johnson Carb rebuild

Well, this is a conundrum. Personally, I would hold off until something really needs service. If she's running like a champ, why take a deep dive?
Back to your question. You can do the rebuild yourself. You sound capable. Use a digital camera to keep track of parts sequence. Remove the old Welch plugs and clean the jets with a cleaning tool or wire. Wash all with acetone (carb cleaner) and compressed air.
Visit http://epc.brp.com] No worries. You can handle it. J

 

[Steele329]

Re: 70 Johnson Carb rebuild

Thanks guys. Should I be worried about the fuel leak from the air box though?

 

[Hdog412]

Re: 70 Johnson Carb rebuild

On the first page of the Johnson/eve forum, there is a section called sticky Top Secret click in to that and you will find a post on carb rebuilding worth it's weight in gold (at today's prices) SHHHHHHHHHHHHH it's top secret

 

[JohnWI]

Re: 70 Johnson Carb rebuild

Mine runs fine (right now) but also has that pesky carb leakage which (as far as I can guess) happens only when I tilt but I'm not sure.

I changed the gasket on the carbs as well as the silencer cover but it seems that it still leaks.

My question is how tight are you supposed to torque a screw into the plastic cover??? I don't need to strip it out. I don't understand why the gasket is cork and not "rubber."

 

[Steele329]

Re: 70 Johnson Carb rebuild

I don't know of any specific torque for the screws, but again I have read that changing the gasket isn't the solution. Its something to do with the carbs leaking back (again from what i read) and that a carb cleaning or rebuild is supposed to solve the problem. I have not done anything yet for the sake that the season is in full swing and I don't want to screw anything up and be off the water too long. Probably not the best idea, but for now thats what I am doing... Good luck JohnWI and let me know how you make out.