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General Category >> Rubber Side Down! >> Will it hurt to leave the choke on?
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Message started by babbalou on 07/30/05 at 18:47:28

Title: Will it hurt to leave the choke on?
Post by babbalou on 07/30/05 at 18:47:28

Today, curiosity pursuaded me to pull the choke out 1 click to see how it would run after fully warm. Amazing difference! I expected stalling & sputtering but it totally eliminated all backfiring, ran smoother, quit surging & had a little more power. I've had my gas tank off LOTS off times messing with the jetting & no combination ever worked this well. Currently I've got the pilot screw out 1 1/2 turns, the white spacer is 1/2 width & a 147.5 main jet. My question is, if I don't end up fouling plugs, would it hurt to just leave the choke out 1 click always? Also, is it a choke or an enrichner? Thanks for any answers. :-/

Title: Re: Will it hurt to leave the choke on?
Post by babbalou on 07/30/05 at 18:58:26

I forgot to mention this! Stock pipe, K&N drop in filter, snorkel out & I sawed a chunk out of the airbox, lower rear corner. Thanks!

Title: Re: Will it hurt to leave the choke on?
Post by GaThumper on 07/30/05 at 19:10:28

The choke is an enrichener, or has an enrichening effect, so I'm not sure what differentiation you are trying to make unless you are looking for something that doesn't restrict air flow & just dumps extra fuel. It restricts air & also helps vacuum pull more fuel. It may be fine, depending on your driving style, but it will ultimately restrict performance the farther you open up the throttle because you'll never get the max air flow the carburetor is capable of as long as the choke is partially closed.

Found this which may help:

When the engine is first started, a very rich air/fuel mixture is required because cold fuel vaporizes slowly. The "choke" at the top of the carburetor provides the richer mixture by closing and "choking off" the carburetor's air supply. The choking effect also creates an area of low pressure inside the throat of the carburetor that helps to pull additional fuel through the main metering circuit. At idle there isn't enough air flowing through the venturi to pull fuel through the venturi discharge nozzle. By temporarily choking off the air supply, however, manifold vacuum rather than venturi vacuum helps to draw the extra fuel through the main metering circuit.

Title: Re: Will it hurt to leave the choke on?
Post by GaThumper on 07/30/05 at 19:12:23

babbalou wrote:

I forgot to mention this! Stock pipe, K&N drop in filter, snorkel out & I sawed a chunk out of the airbox, lower rear corner. Thanks!

You may need to rejet to account for the improved air flow with the K&N.

Title: Re: Will it hurt to leave the choke on?
Post by CHRIS on 07/30/05 at 20:10:11

You may also just need to bump up on one of the jets. if it preforms poorly on the low end then bump up on the pilot, if it's mid-range you could adjust the needle, and if it's top end bump up the main jet.

Title: Re: Will it hurt to leave the choke on?
Post by CHRIS on 07/30/05 at 20:20:36

Something else you may want to try before re-jetting... With the bike cold turn the air/fuel screw in to about 1 turn out, start the bike then slowly turn out the screw, stopping about every 1/4 turn so the carb. catches up. You should hear the idle picking up and the engine sounding better. Once you get to a certian point the engine will start to come back down, when it does, take it back to the best spot, then set the idle back to normal. The idle is not going to come up drastically, but you should be able to hear it. Don't go more than 3 1/2 turns out though, if you get there then you need to bump up to the next jet.

Title: Re: Will it hurt to leave the choke on?
Post by WD on 07/30/05 at 20:37:36

I ran mine with the chole out 1 notch for a week. Gas mileage suffered, but man did the bike behave better. Fouled the plug out pretty quick (in combination with the 2 stroke oil).
-WD

Title: Re: Will it hurt to leave the choke on?
Post by Savage_Rob on 07/30/05 at 23:20:56

In cold weather, I run the choke for about 30-60 seconds after start and then go normal. In the current weather, I never use the choke.

Title: Re: Will it hurt to leave the choke on?
Post by babbalou on 07/30/05 at 23:21:02

Thanks for the input. I tried turning out the pilot screw more but I stripped the groove so I'll order a #55 pilot jet monday. The choke seems to make the biggest difference under 1/2 throttle & by 2/3 throttle it's running well with the choke on or off, so I'm thinking the pilot circuit's a little lean.