Please explain outboard choke settings

Greenheart

Greenheart

Well-Known Member
Joined
29 Dec 2010
Messages
10,385
Visit site
I might have found the answer by waking up old YBW threads, but only along with replies to previously settled questions, so I'm starting a new one in the hope of clear instructions.

I believe it ought to be clear, but I don't know.

50108926102_1f9049ef51_c.jpg


It's a great little engine, starts easily after a few pulls with random choke adjustments, and runs smoothly.

But what positions is the choke meant to be in, when the engine is cold/warming up/hot?

I've no idea if I'm making it work harder than it should, so I mostly leave the choke somewhere in the middle.

Thanks for any guidance...
 
The choke is usually only needed for cold starting and sometimes not even then. Once the engine is running, open it as far as possible without it dying. It should run without it after less than a minute unless you're in Alaska! You shouldn't be running with it part closed once warm, you'll soot up the engine.
 
Close the choke to start the engine when cold

Open it as the engine warms up .

Should be fully open for normal running

Partly close it perhaps when starting a warm but not hot engine ..... experiment to find out how it works best

If it starts easily from dead cold with the choke open it may be flooding a bit or set too rich

What is it . 2 HP mariner ?
 
Thank you gents, that's very clear.

It's a Tohatsu 3.5 two-stroke, a little belter.

The strange thing is, several times I've started it and found that it wanted to stall if I closed the choke, whereas it was revving hard with the choke open. I thought the choke was meant to allow the engine to run richer when cold, encouraging high revving...so I had assumed the 'open' position meant unconstricted for easy starting, and that 'closed' is for normal running.

It hardly matters as long as I haven't damaged it, and it seems fine.

I'll remember to open the choke as early as possible. (y)
 
Vic S has explained how to use the choke correctly.
To tidy the control levers up a bit slip an inch of soft fuel pipe over them, secured with a screw through the threaded hole. Used to do it for motorcycle switches when they were missing. :)
 
dancrane said:
Thank you gents, that's very clear.

It's a Tohatsu 3.5 two-stroke, a little belter.

The strange thing is, several times I've started it and found that it wanted to stall if I closed the choke, whereas it was revving hard with the choke open. I thought the choke was meant to allow the engine to run richer when cold, encouraging high revving...so I had assumed the 'open' position meant unconstricted for easy starting, and that 'closed' is for normal running.

It hardly matters as long as I haven't damaged it, and it seems fine.

I'll remember to open the choke as early as possible. (y)
Click to expand...
The choke is a flap that almost completely closes the air intake to the carb . This means that the engine pulls in a very rich mixture which helps starting when cold. Once started the choke has to be progresively opened to allow the normal air flow.

They vary. With some you have to partly open the choke quite quickly whereas with others more slowly is the way.

If you close the choke when the engine is running you will restrict the air going in and the engine will get a super over rich mixture and most likely die.

You young whipper-nappers should be time transported back to the 1950's and be made the learn to drive cars with manual chokes, points ignition, gearboxes without synchromesh on all the gears, no powersteering, no air con ... not even heaters unless you paid extra. On the plus side though ...starting handles
 
VicS said:
You young whipper-nappers should be time transported back to the 1950's and be made the learn to drive cars with manual chokes, points ignition, gearboxes without synchromesh on all the gears, no powersteering, no air con ... not even heaters unless you paid extra. On the plus side though ...starting handles
Click to expand...

My first three cars didn't have a radio either.

I got one fitted eventually . Only two options. Radio Caroline and
Radio Luxembourg . Spelt KEYNSHAM .:cool:
 
VicS said:
The choke is a flap that almost completely closes the air intake to the carb . This means that the engine pulls in a very rich mixture which helps starting when cold. Once started the choke has to be progresively opened to allow the normal air flow.

They vary. With some you have to partly open the choke quite quickly whereas with others more slowly is the way.

If you close the choke when the engine is running you will restrict the air going in and the engine will get a super over rich mixture and most likely die.

You young whipper-nappers should be time transported back to the 1950's and be made the learn to drive cars with manual chokes, points ignition, gearboxes without synchromesh on all the gears, no powersteering, no air con ... not even heaters unless you paid extra. On the plus side though ...starting handles
Click to expand...

I'm glad to earn the assumption of 'young', whatever the context. :ROFLMAO: Once again, I'm grateful for this very clear description.
 
dancrane said:
It's a Tohatsu 3.5 two-stroke, a little belter.

The strange thing is, several times I've started it and found that it wanted to stall if I closed the choke, whereas it was revving hard with the choke open. I thought the choke was meant to allow the engine to run richer when cold, encouraging high revving...so I had assumed the 'open' position meant unconstricted for easy starting, and that 'closed' is for normal running.
Click to expand...
My 10HP two-stroke behaved a bit like this last year. This spring it would start but quickly immediately died under any load - cleaning the carb sorted it.
 
20200714_173201.jpg

I am sure Dan and i both understand how a choke works.
I think i understand Dans problem:
Picture is my Evinrude 3.5 which i acquired second hand. (no doubt a re badged Tohatsu

The choke is in the run position ie no choke. Compared to the label it has always seemed backwards to me...
 
You must log in or register to reply here.

Share this page

Top