dumb choke question

[Anonymous]

What does the choke actually do? does it allow more air into the carbs? restrict the air? allow more gas? or restrict the gas?
I am doing some trouble-shooting and it would really help me out if I understood its function.
Thanks
Tom

[lhanscom]

It adds more gas.

[moto_dan]

Re: dumb choke question

What does the choke actually do? does it allow more air into the carbs? restrict the air? allow more gas? or restrict the gas?
I am doing some trouble-shooting and it would really help me out if I understood its function.
Thanks
Tom

It enrichens the mixture by routing fuel into the carb throat on the engine side of the carb butterflies. What Luke said

[Anonymous]

If I remember correctly... The choke doesn't exactly just "add more gas". The choke system in the carbs is separate from the main system. On a CV carb it operates based on the pressure difference (I believe) between one side of the butterfly valve and the other.

Sometimes when someone is trying to start the bike with the choke on, and they think it's not getting enough fuel, they will try a bit of throttle as well. What actually happens in this case is that you remove some of the vacuum the choke is operating with, and switch some of it over to the less-effective main system. You actually wind up getting a little less fuel into the engine this way. (If I'm mistaken, please correct me.)

Anyway, bottom line is that the choke is a separate system within the carb. It may or may not richen the mixture depending on throttle position.

Michael

[lhanscom]

Correct, when you open the choke it causes the slide to raise, which allows more gas to get into the mixture. With the throttle closed this will create a rich condition. As soon as you open the throttle more air is allowed to come in, and the 'choke' is eliminated. The final effect is that more gas gets to the engine when the choke is used alone.

[moto_dan]

What Michael and Luke said 8O Here's a link that may help with carb tuning in general http://www.f6rider.com/VRCC/tech/carb101.htm

[Anonymous]

Great info!
I have noticed that when I apply the throttle when I first try to start the bike (w/choke on)that it never starts.
Thanks!!
Tom

[moto_dan]

Great info!
I have noticed that when I apply the throttle when I first try to start the bike (w/choke on)that it never starts.
Thanks!!
Tom

If all is working as designed then the starting formula is no throttle and full choke. If the bike as set for a couple of days then I usually put the petcock on Prime for a few seconds to fill the carb bowls. Bike should idle fairly high 2k rpms or more, then as you gradually take off the choke idle will decrease after several minutes. Sounds like you're making progress.

[Anonymous]

It starts right up when full choke is applied and no throttle,
and will idle fine immediately after it starts without the choke. but for the 1st 5 minutes, without the choke, if I apply any throttle at all it immediately dies.. I have to slowly back off the choke for the first 5 minutes of riding..after that its fine.. Is this just a normal part of warming up?


And I will check again, but I am thinking it shoots up to about 4000 rpms with the choke on full..
Tom

[lhanscom]

With my 700 I can pretty much take off as soon as I start it, with no choke or some choke. If I don't have the choke on and I stop, it may stall, but that's it. That's with the CV carbs. The 750 has VM carbs, and it seems to like to warm up a bit before it will except the throttle.