I have a 2003 yamaha ttr 125. At times it acts like it isn't taking gas and five minutes laterit is running fine. Sometimes it will even stall out on me.

youtube.com

If the bike has an electric stater it is a 125LE if it doesnt it is either a ttr125 or a ttr125L

the serial number should contain all the information needed

There is a frame number stamped on the frame neck. If you call a dealer they can look up the year and model using an ID microfiche. Next to the stamped frame number there should be a riveted plate with the VIN number on it . If this plate is still on your frame it also has the model number and the model year of the motorcycle clearly printed on it. All Yamaha dealers have the ability to ID your machine using the Vehicle Identification Number.

The TTR-125 Carburetor's Run Lean by design. Mine had the same issues till I found a post on Thumpertalk.com on Carb and air box Mod. This is a good starting point on gets; 110 and 112.5 main and 17.5 pilot. But you must check spark plug coloring to make sure the jetting is correct. Check spark plug after the bike has been ridden for a wile. I also took out the stock baffle and replaced it with exhaust tip and now it fires up after a few kicks and worms up in a few minutes.

you need to clean or replace the float valve in the carburator.

Hi and welcome to FixYa,

It uses a 4-stroke engine.

Good luck and thank you for asking FixYa.

look to see if the clutch is burned out thats what happened to my ttr 125 and we change the clutch and it was fine then hope this helps

download the repair manual here
http://www.torrentreactor.to/search/haynes+yamaha+ttr+125+repair+manual

valve lash on the intake .003 to .005 inch, .08 to .12 mm,exhaust .004"to.0055 inch,.10 to .14 mm (cold engine).