1972 Johnson 100hp carbs with no mixture screws?

[oldrudedude]

Ok, So I tore the carbs apart on my "new" 72' Johnson 100hp (100ESL72R) to clean and adjust mixture screws. I do that to all my engines as soon as I get them. But, I didn't find any mixture screws. This is especially surprising considering the air induction cover has 4 holes plugged with plastic caps. I'm pretty old school, but I can't remember cleaning a carb without mixture screws since my '62 Chevy. Did I miss something/

 

[RobSS]

Re: 1972 Johnson 100hp carbs with no mixture screws?

The low speed needles are easy to miss. They are located in the bottom corners of the IVA type Carburetor one on the port side one on the starboard side. be careful if you decide to remove them there is a retainer and a small bearing/bushing. as far as a high speed you can remove them but they are not adjustable. So after soaking i just blow them out with air because they are soft brass and can be easily damaged if you try to remove them.

 

[RobSS]

Re: 1972 Johnson 100hp carbs with no mixture screws?

If you have the IVB type there is no adjustments i am aware of just make sure they are clean and you should be good to go

 

[F_R]

Re: 1972 Johnson 100hp carbs with no mixture screws?

If you have the IVB type there is no adjustments i am aware of just make sure they are clean and you should be good to go

Hopefully, the original poster of this thread has it going by now. The thread was started back in July.

Anyway, the '72 100 hp does not have mixture screws. Both high and low speed jets are fixed orifices. The plastic plugs in the cover are because the cover was used on older motors that had adjustable low speed needles. Good riddance!!!

 

[RobSS]

Re: 1972 Johnson 100hp carbs with no mixture screws?

I think i may be in a rare situation or somebody stuck different carbs on mine. I know i have adjustable low speed mixture screws and i know i have a 1972 engine model # 100ESL72R. Crap...