Johnson 20hp carb question

[SKE60]

I have a 1985 Johnson 20hp model J20CRCOS. There is a slow speed adjustment needle valve that sits at the top of the carb and was wanting to know if anyone knew the correct setting for as in number of turns from soft seat. This boat has been sitting up for about 7 years and was given to me and have rebuilt carbs and fuel pump and runs fine, just would like to know the correct setting. Also, possibly the correct fuel float height. Thanks in advance.

 

[alangf]

Re: Johnson 20hp carb question

I have a 1985 Johnson 20hp model J20CRCOS. There is a slow speed adjustment needle valve that sits at the top of the carb and was wanting to know if anyone knew the correct setting for as in number of turns from soft seat. This boat has been sitting up for about 7 years and was given to me and have rebuilt carbs and fuel pump and runs fine, just would like to know the correct setting. Also, possibly the correct fuel float height. Thanks in advance.

Most low speed needles preset 2 1/2 turns out from the seat. I have found this to be a good starting point. High speed jets (if present) normally preset 1 turn from the seat and usually has to be leaned out to roughly 3/4 turn for optimum performance.

 

[psteurer]

Re: Johnson 20hp carb question

On my 1989 20hp, the idle speed needle valve according to OEM manual is set at 1 3/4 turns out. The high speed and intermediate circuits are controlled by fixed jets and require no adjustment. For the float, usually setting it parallel to float housing is the proper height. Some set it so that the unhinged end of the float is very slightly higher than the hinged end.

 

[SKE60]

Re: Johnson 20hp carb question

Thanks to you both. I guessed at two turns so I'll try from 1 3/4 to 2 1/2 and see which works best. Fuel float was level so I'll just leave at that since running fine. Also meant to ask for plug gap if anyone has. Thanks again.