What does the choke lever ACTUALLY do? Why do we need to use a choke lever?!

Hey Everyone!

I thought I'd show a quick video of what ACTUALLY happens to your small engine carburetor when you access and move the choke lever.

This applies to all small engines with a choke, but in this case, it is on a 7hp 2 stroke Toro R-Tek engine.

The choke lever is attached to a butterfly valve inside the carburetor, which closes (almost) fully when the lever is actuated completely. This prevents the full amount of air into the cylinder and instead allows a richer fuel mixture (as the same amount of fuel enters the cylinder). This is done because a cold engine needs more fuel to start, especially in a snowblower when its very cold! Once the engine warms up, that's when its time to reduce the choke and eventually back it off completely to run at maximum effort!

Thanks for watching!

-Dave

[stellarproductions]

You explained it perfectly! Fuel enrichment 100%

[MrAlkanet-ntic]

finally someone that doesnt talk 3 hours in order to explain sth that can be explained in 3 minutes tops! thx mister!

[thenewman]

Yes, choking basically means less air more fuel, in that choking the carb restricts the volume of air that can go in at any given time, increasing the air draw force inside from the engine vacuum, which now has the necessary air velocity to pull more fuel in from cycling the engine.

[bigdawg]

I've always known what chokes do, but never why they do it. This answers my question. Thanks!

[canoetipper]

some of us are old enough to remember the white knob on the dash with "C" on it...lol. 😉
good explanation, thanks.

[billbaber]

Thanks Dave I’m 70 Yo and the best explaination I’ve seen, from Deep South never seen a snow blower, however got yard tools.

[Mr_Tecumseh]

Good to see Dony's apprentice taking full advantage of his teacher's wealth of knowledge and resources. 👍

[jodia]

I just love guys who like mechanics. Thank you for the explanation!

[Luigi-pkmk]

Choking actually increases the venturi effect which pushes more fuel from the bowl to the jets. The reason why is that when you increase the Venturi effect you are lowering the atmospheric pressure in the Venturi versus normal atmospheric pressure in the bowl (14.8 psi or 1 bar at sea level). So it is the pressure difference that enriches the fuel mix not restricting air intake per se….
Carburetors work on pressure difference and flow from the carb bowl to the venturi is accomplished by lowering the atmospheric pressure in the venturi.

[lazarusblackwell]

So thats what its for.

I needed to see that.

No one so far was able to explain it.

[Nettle]

Great, cheers! Short and concise as we like it

[carolinafine]

You’re the best. Thanks for the explanation

[buckybarnes]

I always thought it regulated gas flow. So like full choke was the most amount of gas allowed into the engine for a cold start, and then not so much gas (choke off) as it gets going and warms up. Oh well lol, thanks for the lesson

[sarahjean]

thank you thank you thank you thank you thank you thank you.... like seriously. idk why I just couldn't understand, but thank you for somehow getting through my thick skull!!!!

[davidruiz]

Thanks for the video, question Echo SRM 230 will start only if sprayed with carb. cleaner..what may something for me to check. Again, thanks and God Bless

[ToddAdams]

Anyone that’s ever had to rebuild ANY carburetor (small engine, automotive, or other) knows why you MUST have a choke, just to get it started. However, they can also be useful for extremely rudimentary diagnostic tools of sorts (and fast too).

[LomaHassell]

Thanks, Dave, for the quick answer. You mentioned that you were cleaning your carburetor with an ultrasonic cleaner. Can you share the settings on your ultrasonic cleaner, cleaning solution, and time? Many thanks.

[shermansawparts]

What solution do you use in your ultrasonic cleaner?

[thomasfranche]

So... once you chock the air and prevent it from entering the cylinder, letting only fuel to enter, then a "cold" motor can more easily start. Once started, they you remove the choke and let the air mix with the fuel again ?

[timduncan]

So when I put my choke down is that a bad thing like will it mess it up or do I have to stay it up if that makes sense