pilot jet
 

hey i bought a 98 yamaha xt 350 with 536 miles on it.
and the carb. was pretty gummed up, i cleaned it out and it runs fine when it is warmed up. but when its cold it takes many strokes to get it fired up and it pops and backfires for about 1 to 2 mins. also if i push the choke all the way in it will die, so i have to keep it out about 3/16 of an inch.
now heres my question the pilot jet is it hollow all the way through?
because i have tiny wire brush set used to clean paint guns and i can only go in a little more then half way on one side and just about to the small holes on the other side.
something else i noticed is the mixture screw can be adjusted all the way in or taken all the way out without effecting the idle.

Blocked pilot jet, is my opinion. If the bike is 11 years old and has only done 500-odd miles, than it has likely been standing for a long time. Petrol evaporates and leaves deposits the block the jets. You say you have cleaned it out, but did you use proper carb cleaner? A wipe out with an oily rag isn't enough :) Clean it out meticulously with proper cleaner, and don't poke around in the jets with wire - you can do more harm than good. Soak the jets in carb cleaner and blow out with compressed air. Onjce you have the pilot jet clear, it will start properly (easy cold, harder hot), you will be able to adjust the idle, and it will run without the choke.

Brilliant bike, by the way. I've had two (the early full-power version and the later restricted one) and they are about the best dual-purpose bike there is. Good luck with it.

should you be able to blow through the pilot jet?

Yes, otherwise how would the fuel get through? :)

I'm not sure if you can see through the hole, as some jets have mutilple holes at one end to improve spray pattern, and this means that there isn't a straight way through the jet body. But you should be able to blow through it, and if you can't, it's blocked.