I bought my 2005 yfz 450 about 2 months ago as a left over 05. It is stock as of right now but i have ordered a BMC air filter, Dyno-Jet jet kit, and full carbon-fiber yoshimura exhaust. Yesterday i put on a motion pro twist throttle and today while trying it out my quad started acting up a little. It seems as though it's not getting the gas it needs, when i come to a stop it trys to cut off and when i give it a lot of throttle it also does it again. I took the baffle out of the exhaust shortly after i had it but put it back in, can that be a reason, maybe it made it run lean and i need a new spark plug? But if anyone knows what could be making it do this let me know, thanks

 

I don't think you messed anything up, sounds like the carb is just a little off. Did you play with the idle screw at all when installing the twist throttle?

 

you need to make sure the wires that were hooked up to the thumb throttle are tied together