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81 XT250 Choke issues

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Hey Guys,

 

I just got my hands on a 1981 XT250 in mint condition with only 3,600 miles on it.

I have checked valves.

Compression is metering manual spec levels.

New spark plug and battery.

Carb as been cleaned and has all new brass and gaskets.

 

My issue is that the bike will only run with the choke on. It is my understanding that the choke acts as a fuel enrichment.

I am currently at a lose as how to fix this problem.

 

Any help would be appreciated. 

 

-NG

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Classic symptom of a carb passage and/or jet still plugged-up, particularly the pilot circuit if it won't idle off choke.

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Hey YZEtc,

 

I took all the brass and rubber off the carb and soaked it in carb dip for 20 minutes and then blew out all of the passages with my air compressor. I slapped the carb back on the bike and had the same issue. Would not idle or run with the choke off. Do I need to keep soaking the carb in carb dip until it will idle with the choke off? Any other ideas?

Thanks for the help so far.

 

-NG

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Yes.

Be certain every passage is clear, like where the fuel screw, pilot jet, and air jet openings are.

 

Also, what's the condition of the air filter and airbox?

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I put a new air filter in and the air box is in good shape. I will dip the carb again and make sure to hit all the passages a second time. The only thing I have not checked yet is float height. So I will probably check that today as well to make sure I am getting enough fuel to feed the pilot jet. An thoughts on that theory?

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Possible, as who knows what it may have had done to it since 1981, although I don't know how far off it would have to be in order to give you trouble like that.

Should be checked, anyway.

Edited by YZEtc

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I checked the float height and it was in spec. I dipped the carb for another 20 minutes and blew out all the passages with my air compressor and I am still having the same issue. I have noticed that I can let off of the choke more now and almost get the bike to idle without the choke on. I can move the choke lever up to just before the choke is off and the bike runs, but at a lower rpm. Once I pull the choke lever all the way up and the choke is off the bike dies. I guess I just have a really clogged pilot circuit. Back to the carb dip we go.

 

-NG

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While you were dipping, and blowing, did you physically remove the pilot jet, and clean it? Did you remove the fuel screw while it was soaking?

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Is it still like this once it warms up?  The old XT's were fiercely cold blooded.  I used to have to start mine and let it sing with the choke on while I got ready to go so that I could ride away without it stalling.  Once it warmed up though it ran fine.

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If that's the case, check the carb vent tubes. They go down under the back of the crank case, and look like overflow tubes.  If they are plugged it can go really lean too.

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