74 Johnson 70HP Carb Rebuild Question

[scotter44]

Hi all, I've been reading the forums and I have a few questions before I rebuild my carbs. In my manual it shows two types of carbs. One has the low speed adjustment needle and the other has what looks like a fixed jet. I have the fixed jet carbs. My motor runs really rough at idle but when I give it WOT it takes right off and runs great. I throttle back and it gets really rough and sometimes stalls. In the rebuild kit it comes with these little caps for the top of the carb. Some say to drill a little hole in them to pop them out and install the new ones with some finger nail polish. Do I have to take them out or if they look of leave the old ones in. What is under these caps or do they just wear out. The other question I have is the fixed jets. They seem to be in there tight. Do I need a special screwdriver to remove them to clean this area or leave them in and run some carb cleaner through them with some compressed air. Any help would be greatly appreciated.

 

[reload]

Re: 74 Johnson 70HP Carb Rebuild Question

I didn't know they had fixed jets in 74.

 

[scotter44]

Re: 74 Johnson 70HP Carb Rebuild Question

I didn't either, but in my manual it shows early and later models. Mine are the fixed ones. I found out the plugs are freeze plus or welsh plugs. Some tell to just remove the top one and clean out that area and install the new one with a tap of a hammer. They also tell me to leave the fixed jets in and just run some carb cleaner and air through and that should be fine. I figure I will just replace all the washers, float, seat and needle after running carb cleaner and air through all the jets and lines.

 

[scotter44]

Re: 74 Johnson 70HP Carb Rebuild Question

I will tackle this in the morning.

 

[jtexas]

Re: 74 Johnson 70HP Carb Rebuild Question

I didn't either, but in my manual it shows early and later models. Mine are the fixed ones. I found out the plugs are freeze plus or welsh plugs. Some tell to just remove the top one and clean out that area and install the new one with a tap of a hammer. They also tell me to leave the fixed jets in and just run some carb cleaner and air through and that should be fine. I figure I will just replace all the washers, float, seat and needle after running carb cleaner and air through all the jets and lines.

That's exactly how I do it, they come out fine - I figure if I ever need to remove a jet I'll acquire or fabricate the tool for it. Drilling the welsch plug, go slow so you don't punch through too hard - there's maybe a half inch clearance or so then the carb body underneath - nothing that will break with ordinary effort.

 

[scotter44]

Re: 74 Johnson 70HP Carb Rebuild Question

Well I did the rebuild today and removed the plugs on top where you can see the low speed jet. There are three little holes and you know what, Yep some were clogged. I used the carb cleaner with some compressed air and cleaned all the carbs and replaced the floats and needles. WOW what a difference. Started right up and idled great. No choke or prime. Thanks for all your help guys.

Scotter44