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??