question on carb choke

[weedahoe]

My bike starts and runs fine. However, I noticed from day one the choke never really worked. I always wrote it off to it being the Brisk plugs but recently I went back to the old traditional plugs to test and it did the same.

What happens is I can start the bike and when I apply the choke, it literally chokes and stalls the engine. There is no raising the RPMs. It just kills it.

Im sure something is wrong but i have zero idea what. Someone give me some insight please.

[prmas]

If it starts easily from cold without the choke it must be too rich. By using the choke it sounds as if you are just overfueling it.

Macka

[RossLH]

Sounds like the choke is drowning the air fuel mixture. Does the bike idle alright at 1200? Are the intake/exhaust/fueling stock?

[weedahoe]

I'm not understanding what you mean by is the intake/exhaust fueling stock. You mean is it jetted? Yes. It has been better to the numbers in my signature.

[RossLH]

Ah, didn't see that. How many turns on the idle mixture screws?

[weedahoe]

2.5 turns out. Zero idle or running issues.

[RossLH]

Whats your gas mileage like?

[weedahoe]

Zero idea. With a tank so small, I never really pay attention. I think I see where you're going though

[Funderb]

vac leak in your choke circuit? your situation sounds pretty strange.

[jestercinti]

My bike starts and runs fine. However, I noticed from day one the choke never really worked. I always wrote it off to it being the Brisk plugs but recently I went back to the old traditional plugs to test and it did the same.

What happens is I can start the bike and when I apply the choke, it literally chokes and stalls the engine. There is no raising the RPMs. It just kills it.

Im sure something is wrong but i have zero idea what. Someone give me some insight please.

Had a bike that did that once.  Choke never worked.  Was a bit too rich per my plugs, but just rode it 6000 miles until I sold it.  Some things are just strange like that.

However, I have some things to try.  You are pretty handy with bikes, so I am not trying to insult your intelligence:

Choke circuit is choking too much.  Cable adjustment?  When I bought my bike, there was a choke problem.  Took it in under warranty, and they fixed it.  Not sure what they did.

Carb insides spotless?  I am assuming it is, but just checking.  What about the boots and o-rings?

Pilot too rich for air cleaner/exhaust?  Sounds right per your sig...but I am grabbing at straws here.

Vacuum leak somewhere?  Check hoses.

If 2004+, did you check the TPS sensor resistance?  There is a procedure at least in the Haynes manual.

[weedahoe]

I havent checked TPS resistance but will look into it. Im fairly sure there are no vac leaks but I know better than to say there are none so I will re-check. Im smart but not a genius and Im not good at all with carbs. I know they are simple in design but they are still a PITA to work with.

[adidasguy]

Choke: strictly a mechanical thing. There is a slider with a limit on travel. I believe they refer to it as the "starter system" or something like that in the manuals. Often you can't find the word "choke". It lets more fuel in bypassing the mixture screws.

There is that little copper pipe on the side of carbs. That is for the starter system. What if that is broken? Opening the choke would open an air passage, letting in air rather than fuel.

TPS: sensor that only changed timing. Nothing more.
VACUUM SWITCH on the Carbs: Sensor for the ignition timing. Not sure what it does other than sense more vacuum meaning timing gets adjusted.

Nothing alters the fuel/air mixture other than the choke, throttle (which is purely mechanical, too) and all the things you fiddle with in the carbs.

There is nothing electrical to alter the fuel/air ratio on out bikes.

You can lift up the tank and fiddle with the choke lever on the carbs with your finger. As others said, you're probably too rich to begin with. Choke COULD have leaks or other defects in it that is causing the engine to die. Choke plunger assembly could be damaged (Haynes manual shows how to remove it).

As a remote possibility, your choke assembly and cable could be put together wrong or maybe a cable is backwards so choke on=off and choke off=on". Worth getting out the book and check it all out.

[jestercinti]

TPS: sensor that only changed timing. Nothing more.

Good to know about the TPS.  Thought it did more than timing.  Now I know.

[weedahoe]

^^^ That makes two of us. 

[weedahoe]

As a follow up, I re-seated my mixture screws and backed them out 2 turns and the choke will work so looks like you guys were correct on the mixture being too rich and killing it.

THX everyone. Seems I have some more tuning to do.

[bombsquad83]

Another thing that is often overlooked (at least it was by me for a long time), is the jet at the bottom of the float that feeds fuel to the choke circuit.  It is labeled number 3 in the diagram from the manual posted by adidas above.  Mine was completely clogged on one side.  Once I cleaned out these little fuel jets, the choke worked as intended.  I think these often get clogged with varnished fuel and/or crud since they sit at the bottom of the bowl.

[weedahoe]

Thanks for that tip. I had cleaned the carb internals really good when I jetted it. I put my Yoshimura TRS on today and the instant it fired up I grinned. I HAD to take it out for a spin and I LOVE it. I can't imagine what dual Yoshimura TRS sound like but I will soon.