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FCR Carb, Choke no longer works

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The choke on my KX250 stopped working, in fact if you pull the choke it instantly kills the bike. It is impossible to start hot or cold with the choke on. I disassembled the carb and it looks to me that a press in brass ball has fallen out of the passage connecting the starter jet with the choke circuit. Looking at the attached picture does anyone know if the hole shown with the arrow is supposed to be plugged? Anybody have a good fix if so?FCRCarb.jpg

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Does the carb respond properly to the fuel screw?

The fact that the choke has some effect, tells me the circuit is working. What starter jet does it have? Did you test to confirm that with tyhe plunger in, no compressed air can be blown into the starter passage way?

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Does the carb respond properly to the fuel screw?

The fact that the choke has some effect, tells me the circuit is working. What starter jet does it have? Did you test to confirm that with tyhe plunger in, no compressed air can be blown into the starter passage way?

The bike runs perfectly once warmed up and the choke is off. The pilot circuit works fine and the bike responds appropriately to the fuel screw. No compressed air can be blown into the starter passage way with the plunger in. If you pull the choke the bike dies immediatly (at idle) as if it is sucking in raw fuel. It has the stock #68 starter jet. I don't get it?

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Did you try a different starter jet?

Being you confirmed that the choke system appears to be functioning correctly, the only possibility is when the choke is engaged, it is sucking in too much fuel. Is it possible someone drilled out the starter jet?

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Did you try a different starter jet?

Being you confirmed that the choke system appears to be functioning correctly, the only possibility is when the choke is engaged, it is sucking in too much fuel. Is it possible someone drilled out the starter jet?

I've got a new one, have not tried it yet. It is not possible that it has been drilled out, I'm the only owner or person that has ever worked on this bike.

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Hmmmmm

'Normal' choke operation (enricher) is to add fuel AND some air. This provides for a rich fast idle. Typical engine response is an idle and as the engine heats up, for the idle speed to increase. Changes from normal (1,800 rpm) to as high as 3,000 rpm is normal.

As you have surmised, it appears you are getting too much fuel for the available air. Being you are sure the starter jet is fine (and being you are the original owner and know the history) I suspect it is too. That leaves the additional air to be the culpret.

Unfortunately, I do not posess a diagram of the air passages of the FCR so explaining it would be very difficult. There are three points. Air in, fuel in and air/fuel exit. Blowing air in the starter jet with the chooke engaged should result in air in the carb throat AND out the air inlet.

What events occured between the last time the choke worked properly and when it stoped working. It should be one day to the next.

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Hmmmmm

'Normal' choke operation (enricher) is to add fuel AND some air. This provides for a rich fast idle. Typical engine response is an idle and as the engine heats up, for the idle speed to increase. Changes from normal (1,800 rpm) to as high as 3,000 rpm is normal.

As you have surmised, it appears you are getting too much fuel for the available air. Being you are sure the starter jet is fine (and being you are the original owner and know the history) I suspect it is too. That leaves the additional air to be the culpret.

Unfortunately, I do not posess a diagram of the air passages of the FCR so explaining it would be very difficult. There are three points. Air in, fuel in and air/fuel exit. Blowing air in the starter jet with the chooke engaged should result in air in the carb throat AND out the air inlet.

What events occured between the last time the choke worked properly and when it stoped working. It should be one day to the next.

The carb sucked in a bunch of sand due to a leak in the airboot gasket where it meets the airbox. The carb was disassembled, cleaned and reassembled. Bike runs perfect except now you need to flood it with the accelerator pump to start it when cold (because it will absolutely not start with the choke on). That's why I question as to whether or not there is supposed to be a brass ball in the passage shown above-could it have been blown out when being cleaned?

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That sounds the opposite of what you said. You implied the choke was over richening things.

You told me you tested the carb with compressed air. Had there been a leak, you would of found it.

We are spinning wheels here.

When you cleaned the carb, did you split the carb body?

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