How do you adjust the air fuel mixture on a 2003 yz250f?

Answer 1

Two ways:

1. Get a small carburetor screwdriver (about $20 at Cycle Gear, I think). Its only about 1" long and has a couple flat head attachments and a Phillips attachment. You slip the screwdriver head into the bottom of the carb, where the air fuel mixture screw is. You adjust in til it starts to die out, then back out little by little (1/16 turn at a time) til it's at its highest idle. It take a bit of time. Be in a quiet place, lean your head against the seat and close your eyes (sounds corny, but I'm serious). You feel/hear the idle speed more exactly this way.

2. Get an aftermarket screw for this bike. It's longer and has a knurled end so you can turn it with your fingers while the bike is running. I think it's about $20.00. Also - go to Thumpertalk.com they are a great resource for 4 stroke dirtbikes, and alot of people have the Yam 250f because it's a great bike. Not sure if I can do a link, but here's a link that discuss this carburetor. '

http://www.transworldmotocross.com/mx/how_to/article/0,13190,589502,00.HTML

here's a link to "Zip Ty " brand fuel screw, but there are alot of other brands. Check your local moto shop.

http://www.ziptyracing.com/products/product_detail.aspx?id=MTEwMQ==