How to tune a automatic choke?

[btaylor507]

I have a 1966 40HP Evinrude Big Twin. I just finished rebuilding the carb and I'm not sure on how to set the automatic choke. Also there is a cylinder with a piston that connects at the bottom. When I disassembled for cleaning the piston fell out and some of the oil from inside. I put the piston back in and put it back on. I'm not really sure what this part does or if its needs replacing. Please see pic below. Any info would be greatly appreciated. Thanks!

http://i689.photobucket.com/albums/vv259/bill8908/2010-08-02231734.jpg

 

[F_R]

Re: How to tune a automatic choke?

There are two things that close the choke plate. One is the hot air actuated bi-metal spring, and the other is the electric solenoid. The bi-metal spring is for partially choking it during the warm-up period. Adjustment of that one is pretty much a trial and error thing. For a beginning point, set it so it closes the choke about half way at room temp. You can then turn it one way or the other to fine tune it so it neither over chokes nor under chokes during the warm-up period.

The electric solenoid slams the choke shut tight for initial start-up whenever you operate the switch on the dash. This is the important part. It will be hard or impossible to cold-start it if the electric solenoid is not operating.

 

[lindy46]

Re: How to tune a automatic choke?

Since those automatic chokes are a pain in the A##@&* to get working right, I end up setting it on manual and just use the solenoid choke to start the engine cold. Once warmed up, you don't need the choke anyway.

 

[btaylor507]

Re: How to tune a automatic choke?

Thanks for the help guys! I hope I dont sound stupid when I say this but this electric solenoid, is there supposed to be a wire coming out? Just to give you a little background. I purchased this motor online and the owner said it runs but when you give it full throttle it cuts out. I'm not really sure how to "set it on manual". Please forgive me, I'm new to outboard motors.

 

[royal0014]

Re: How to tune a automatic choke?

Same solenoid as on my '66 johnny 40, so I assume the carb is the same...

Yes, only one wire to the solenoid, from the choke button or switch, depending on which you have.

There should be a lever on the opposite side of the carb from the choke solenoid. Three positions; forward is on (manuel close) middle is auto (button or switch) and back is off (open)

 

[btaylor507]

Re: How to tune a automatic choke?

So I'm guessing I need a new one. There's a little stub coming out of it. No wire. Could I just run a manual choke cable? Just a idea.

 

[royal0014]

Re: How to tune a automatic choke?

No cable needed, that's what the lever is for.......

 

[bktheking]

Re: How to tune a automatic choke?

Find a used one and replace it or take the one you have apart and solder a new wire in place.

 

[btaylor507]

Re: How to tune a automatic choke?

Oh! I see. I wasn't aware that this lever moved This is starting to make more sense. Thank you F_R, lindy46, royal0014, and bktheking. I'm going to try to solder a new one on like bktheking said. I only have one more post to make then I think I'm good for a while. Have a great day!

 

[bktheking]

Re: How to tune a automatic choke?

I just think you'd have more luck starting it with the proper setup vs looking like a Merc owner having to mess with something under the cowl to get it started

 

[btaylor507]

Re: How to tune a automatic choke?

HAHAHAH! lol I'm a Merc owner also I have a 165 Merc that's sitting in storage cause it doesn't RUN That's next years project.

 

[bktheking]

Re: How to tune a automatic choke?

I am too, just look at the avitars!