Choke appears to flood the carburator | GTAMotorcycle.com

Choke appears to flood the carburator

zheka130

Well-known member
Guys

not a big issue, but looking for some pointers nonetheless.
When I start the bike, pulling on choke all the way, it starts and the immediately dies, as if too much gas is coming in.
Starting without choke works without problems in warm weather, but somewhat troublesome at cooler temperatures.

Any thoughts? Since choke blocks some air from entering, is the culprit in the fuel delivery or perhaps the mixture is choked completely ?
 
Guys

not a big issue, but looking for some pointers nonetheless.
When I start the bike, pulling on choke all the way, it starts and the immediately dies, as if too much gas is coming in.
Starting without choke works without problems in warm weather, but somewhat troublesome at cooler temperatures.

Any thoughts? Since choke blocks some air from entering, is the culprit in the fuel delivery or perhaps the mixture is choked completely ?

It's always helpful if you include year/make/model in your question.
 
Guys

not a big issue, but looking for some pointers nonetheless.
When I start the bike, pulling on choke all the way, it starts and the immediately dies, as if too much gas is coming in.
Starting without choke works without problems in warm weather, but somewhat troublesome at cooler temperatures.

Any thoughts? Since choke blocks some air from entering, is the culprit in the fuel delivery or perhaps the mixture is choked completely ?

In most modern motorcycle carburetors that circuit is a fuel enrichener, not an air 'choke'
There's not much you can do to change it.
As temps drop, air becomes denser and thus requires more fuel for combustion.
You might be able to install a larger pilot jet (it depends on the carb), but that will mess things up when it gets warmer again.
Live with it I'm afraid.
 
I am going to GUESS that the bike in question is the VTR250 that is in your profile.

The "choke" - a.k.a. enriching valve - is not a digital "on/off" device. If the temperature is moderate, the right amount of choke might be a third, or it might be half, or it might be full. Establishing the right amount that your engine wants on really cold start, or somewhat-cold start, or moderately-cool start, requires ... "experience" and "experimentation".

It is not uncommon at all for the engine to want one choke setting in order to fire while cranking but then immediately want the choke to be backed off. Again, this requires experience and experimentation.

If the bike has always acted the same way then probably that's just the way it is.

If something has changed, then it's time to start looking. The first thing to check is the condition of the air filter, because a dirty blocked air filter can make the engine run rich. The second thing to check is the condition and proper operation of the float valves in the carburetors. Make sure they are sealing shut properly when the float bowls are full (not allowing them to overflow) and make sure their level adjustment is correct.

Cracked/leaking rubber intake boots, incorrect valve clearances, etc will wreak havoc with how the engine runs.
 
The "choke" - a.k.a. enriching valve - is not a digital "on/off" device. If the temperature is moderate, the right amount of choke might be a third, or it might be half, or it might be full. Establishing the right amount that your engine wants on really cold start, or somewhat-cold start, or moderately-cool start, requires ... "experience" and "experimentation".

This, exactly. Every small engine with a choke/enrichener will be different as well, so you need to find what works and then go with it.

My VTX for example likes the choke on full to first start from cold but then if I don't back it off to about 1/2 within 10 or 15 seconds it loads up and stalls, but then it likes to be on half way until the engine warms up a little underway. My wifes Vstar will run all day with the choke on 100% aside from an extra fumey exhaust and higher fuel consumption.

One of my old Jetskis (a Yamaha GP1200) would not start without the choke on 100%, but the SECOND it started you'd have to turn the choke off completely or it would almost instantly load up and stall...and then be a real PITA to get started again. My wifes ski would start and purr like a kitten with it on half, only turning it off once you were underway.

So yes, there is no "one size fits all" approach to it.
 
Thanks guys. Yes, it is the VTR250.
So it doesn't cut the supply of air, it enriches the fuel? The cutting of the air supply is an old system then?
 
All chokes vary the fuel/air mixture, just depends on how you do it.

In your case pulling on plunger allows more gas to carburetor so less air in there.

The primer bulb system (think priming a lawnmower) works by creating a vacuum to help suck gas and force it in, thus also messing with fuel/air mixture
 
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Thanks guys. Yes, it is the VTR250.
So it doesn't cut the supply of air, it enriches the fuel? The cutting of the air supply is an old system then?

It opens a little spool valve that contains extra passages for both fuel and air ... the latter is necessary in order to increase the idling speed after a cold start.
 

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