To choke or not to choke.

[Turtleface]

Cold air is denser. More compact. To maintain proper A/F ratio you need more fuel. Hence people cooling the intakes and adding in short ram etc. From a starting stand point its not much of a huge deal until you factor in the lowered compression from a non expanded block and pistons.

Simply said engines are air pumps. The more air it flows the higher performance you get out of it. You can add more air in by making it denser (forced induction or cooling it via intake water cooling, cold air intakes, etc.). Engines flow air by volume. So adding more air into say a 1 foot cube (air shrinks as you cool it) is going to let you dump more fuel into it for proper a/f mix. Likewise forced induction like blowers and turbos compress the air in the cylinder. (more air in, more fuel in) The same goes for fuel too. Colder fuel is denser. So one gallon of gas at 30 degrees isnt holding the same amount as one gallon at 120 degrees.

Heres a little something on gasoline and expansion rates. Its not an end all but it gives you the basics. Its pretty much targeted at gas stations and the like.

http://www.consumerwatchdog.org/resources/DPReportHotFuelUSAJune07.pdf

Its not much, but when you start looking into full race engines and the like every little bit helps. Chef or rapid ray can add more into this im sure. I just touched on the basics and in the upper areas my knowledge is limited on how to execute it. I know most of the tricks and why they work, its just the little this's or that's that add in the extra hp to a motor. That and tuning makes a huge deal.

I thought the reason for the choke was to add fuel to to the cylinders to compensate for the fuel that sticks to the walls before the combustion chamber is up to operating temperature. I've read that it doesn't atomize properly in cold situations, and the fuel falls out of suspension. So you saturate the combustion chamber a little in order to get combustion to occur. Even in 115 degree heat last summer, I needed about 1/4 to 1/2 choke to get her started from a dead cold state, I could take the choke off after about 30-60 seconds. Same deal when it was 40-50 degrees over the winter, when I was riding in at 4-5 am. Ran just slightly better (according to the seat-of-the-pants dyno and fuel mileage) when it was colder, once warmed up, but I attribute that to the aforementioned denser air and fuel charge, since my bike had yet to be re-jetted for it's pipe.

[Danjal]

And for that one you'll need to defer it to another source. Im not so keen on fuel atomization.

[chuckycheese]

Which hand?

I always use my left hand to engage my choke. Is that the best method or will it start easier if I use the other one?

[Larry D]

I always use my left hand to engage my choke. Is that the best method or will it start easier if I use the other one?

I've heard that if you use the other hand, the "choke" will think you're someone else..........

[chuckycheese]

Funny!

I've heard that if you use the other hand, the "choke" will think you're someone else..........

I had to think about that one for a second....then I laughed out loud! Good one!

[Mysuzyq]

I've heard that if you use the other hand, the "choke" will think you're someone else..........

Best to move to injection & dispense with choking altogether.

[Skateguy50]

I pretty much use it full and it fires right up then back off. If the engine is hot and I only stopped for a short while it wont start with choke but starts right up with none.

Probably should par more attention but I just back off the choke as soon as it fires to like half in the morning and slowly from that till it runs without it. By the time I got my gear on its always ready to roll.