To choke or not to choke.

[Larry D]

Hi Everyone, I haven't asked a question in awhile so, here goes.....

First of all, I know it's actually an enriching circuit.....

When starting one of our bikes from stone cold, how much choke should be required ?

I ask because I've seen some threads here where folks will say..."My bike starts right up without any choke at all."......Sorta like that's a good thing....is it ?

Seems to me that being able to start up without any choke at all would mean the idle/air adjustment screws are set to rich, thereby not needing much choke.....right or no ?

 

[Steve]

Most of mine don't require more than HALF of the travel of the enrichment circuit. :-\\\

Yes, it will start with more, but as I back it off, it runs better, so I usually start about half-way.

I agree that starting without using the "choke" might mean it's a bit too rich, but only plug chops will tell.

.

 

[BassCliff]

Hi,

I'm in the habit of using about 3/4 choke on my bike when it's stone cold. Maybe I don't have to use that much.

http://www.youtube.com/watch?v=PTnCPwuIQLk

I agree with Mr. Steve. If it starts cold with no choke the pilot circuit is probably too rich.


Thank you for your indulgence,

BassCliff

 

[Danjal]

I use full choke and back it down to 2k or less rpm's as needed. Typically it fires right up and hits over 2k. Just the humidity and temp here effects it and runs it up or down from there.

 

[Larry D]

Thanks for the answers guys.

 

[chuck hahn]

I concurr with GS110GKs method..thats how i do it too..start,,feather the choke,,let warm up well.

 

[Dave8338]

About 1/2 choke for me as well. When temps are in the 40's, it needs full choke.

 

[tkent02]

Above about 75 degrees F, it shouldn't need any choke at all if the pilots are set about right. The colder the temps, the more will be required. A cold engine starting fine with no choke in cold weather is a sure sign of over richness.

 

[Larry D]

Above about 75 degrees F, it shouldn't need any choke at all if the pilots are set about right. The colder the temps, the more will be required. A cold engine starting fine with no choke in cold weather is a sure sign of over richness.

However, you're saying that a cold engine should start fine without any choke at about 75 degees F........I'm still learning about a proper tuning, but, to me, that would indicate richness as well.....No ?

What difference does the temperture make ?

 

[Danjal]

However, you're saying that a cold engine should start fine without any choke at about 75 degees F........I'm still learning about a proper tuning, but, to me, that would indicate richness as well.....No ?

What difference does the temperture make ?

Think cold air intake here Larry.

 

[Larry D]

Think cold air intake here Larry.

Okay......I thought about it......Did I mention that before my 2 year education in the ways of the GS jedi, I knew next to nothing about engines ?

I know that colder air makes more horsepower....right ? So, how does it effect starting our engines, as it relates to the choke ? Colder air is more dense and therefore more enriching is needed ??

I'm realizing that it's a fine line for a well tuned GS. How the heck did they ever mass produce these things and have them tuned correctly leaving the factory ?

Just trying to educate myself.

 

[Danjal]

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.

 

[Guest]

Full choke for this little duck . Back it off till idle settles to around 1500 rpm till it warms up (time it takes to put the riding gear on) and away we go . Hot or cold (weather) doesn't make a lot of difference , only affects how long it takes to warm up .

Cheers , Simon .

 

[Larry D]

Thanks for explanation Danjal, I appreciate the info.

To be honest, the reason I asked this to begin with is my GS750L. I recently got a set of stock exhausts for it. Before I had an MAC single wall exhaust and the pipes turned a nice blue/gold color about 2 inches down from the header. I figured it was just the single wall exhaust because the bike runs great and the plugs look a nice tan color.

After I put on the stock duel wall exhaust, the pipes again are turning the blue/gold color. I pulled the plugs the other night and they look good, a nice tan color.

The thing is, I need very little choke to start it up and after a few seconds, I can shut off the choke and it will idle nicely at 1100rpm. So, I was thinking that I'm a little rich and the discoloring pipes are being caused by unspent fuel igniting at the hot header exhaust.

 

[1_v8_merc]

I put my choke about half way maybe less, fires up to 3k, I back it down to 2.5k for a few seconds, then let it sit at 2k for a minute or so, then down to 1.5k.
All in all, I only let it run for a couple minutes, take off and once I get in 4th
or 5th gear, I take the choke off.

Usually it holds fine, occasionally it will stall If I don't let her warm
up enough, but usually I can tell what mood she's gonna be in by listening to it.

It's taken months and months of riding to get the bike to fire up with barely half choke.
It used to require full choke and took damn near 20 minutes in the winter.

I think it's a combination of the season warming up and the fact that the bike is actually being ridden
regularly instead of just sitting.

I 'll tell ya, these bikes really don't like sitting!
I let mine sit for 3 or 4 days to a week, and she don't sound happy! Lol.

 

[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?

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!

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!