trx450r problem

i gotta 04 trx450r.few weeks ago when i was racing it started to spudder when i would give it alot of gas..i couldnt get on it hard.like it would bog it down.and i rode it at the house a few days later and it didnt do it..then the other day at a race it started doin it even worse when i didnt even go a mile..came up on a hill and it started to spudder and i tried givin it more gas to get up it and it cut off..anybody got any ideas of why its doin this?its like when i give it gas it like cuts in and out??

Sounds like a carb problem to me, have you cleaned the carb lately?

yeh its all clean now.but still doin it

the ethanol takes a toll we run startron in everything at our shop, id pick up some yamaha carb cleaner dip and soak it in that, should cure your problem

Check the fuel filter, that's a classic description of a dirty fuel filter.