A forum for owners of Yamaha TTR250 trail and enduro bikes!

Hi there and welcome to the new forum 

Something that might be causing your problem is the inlet stub between the head and the carb. The rubber section that attaches to the carb can part from the metal stub that attaches to the head and allow air leaks and cause spluttering etc.

See pic below. The metal stub is on the left.

Brian

It is supposed to be in one piece 

Part # 4GY-13586-00-00

Some owners make repairs - see the TTR250 FAQ at http://www.ttr250.com/#Carburettor

Carburation problems? Check the rubber inlet manifold between the carb and the cylinder head as it may have come apart. The aluminium part that bolts to the head is tapered so gluing the rubber back on isn't easy. When the rubber comes adrift it sucks air into the engine upsetting the fuel/air ratio and causes poor running. It's also a very common fault and I've seen it on 2003 models. To glue the rubber back on you will need to remove the airbox, carb and inlet stub. Then clean it as best you can with a solvent that evaporates - meths, acetone etc. Then use an epoxy adhesive to coat the stub and push the rubber back on. Clamp end-to-end and put a jubilee clip (hose clip) around the glued area but not too tight. When the glue has dried (24 hrs is good) drive a couple of self-tapping screws through the jubilee clip, through the rubber and into the aluminium stub. If you're fussy, Dremel the ends of the screws inside the inlet stub.