Just bought a 04 yfz 450. Noticed the header glowed at idle after about 1 minute. I wanted to clean up and familerize myself with the carb, so i started going through it and noticed the needle tip to the thumb screw thats located on the bottom of the bowl was broken off and stuck in the carb. I beleive it is the air bleed for the idle mixture. I tried pushing it out by pushing a small tack down through the top but im not sure how small the top of the needle seat is. I dont want to enlarge the top of the seat. Any ideas????

 

i believe the factory carb. is a kehein fcr. they are mechanic friendly. the thumb screw you are describing should be the idle screw, if it is located on the actual bottom of the float bowl it is either the bowl drain or the accelerator pump. i would take the carb. apart if you are comfortable and do you have a repair manual or can you take the carb. to your mechanic. either way dont be intimidated it should be an easy repair and carb. parts are abundant.

 

as i re-read your concern it may be threaded where it broke off, so i would be careful about pushing it through. see if you can get an exploaded view from book, dealer, or net.

 

I have already looked at the replacement needle. Here is a pic. Fuel Mixture Screw Keihin FCR Carbs CRF YFZ 450R 450:eBay Motors (item 140344756622 end time Jan-06-10 06:03:33 PST)
It is the very tip. It is only about .030 at the widest point of the needle and about .125 long.

 

ok i see the image of the mixture srew, could you use a welder tip cleaning tool, paper clip diameter, or if it is bottomed out in the bore can you use compressed air through the mixture passages, i used to run into same problem in certain auto trans valve bodies. if it is steel use a magnet and paper clip or use grease on the end of a paper clip or similar. i share your pain it can be frustrating.

 

got it!!! I had to get a hollow torx bit and split another part of the carb apart. I was able to get to upper side alot easier and tap out the broken piece. Thanks for input.

 

cool, i pulled up a view of that carb. and saw your surgical plan in process, glad surgery went well. enjoy the machine i got an 09' yfz450r with some mods and just had a power cammander put in, but it's pretty cold here in wyoming i havent had a chance to play much. happy new year.