Why won't my Yamaha TTR 125 run when I turn the choke off?

Answer 1

check for a plugged slow jet in the carb.

First, insure that there is no blocked internal passages within the carb-while the jets may be clear, other passages may be gunked up.

If it's still running on choke, but not on "run" position when the engine is warmed up, you're too lean. The choke circuit richens the mixture, so when it is on, you're artificially enrichening the mix, so you need to go up in jets....I'd start with going up to a larger pilot.

Or

Well instead of doing all that stuff, did you check your pencock on the side of your tank to see if the fuel is switched to "ON".. If not that then you dont have fuel in it or there is a blockage..

Tom

I had the same issue and cleaned the carb with carb spray and compressed air several times with no sucess. Then I bought a 1 gallon can of Berrymans carb cleaner (soak with tray in can - $23) I took the entire carb apart and placed all items except for the plastic and rubber parts on the tray and submersed for 30 min. Rinsed with water and blew out all parts with compressed air and it idles perfect and runs great with no changes to jetting.

Dan