i have a 04 trx 450 r i live in orlando fl. the only thing i did was a 13 tooth front sproket and removed the spark aresstor i ordered a k&n filter with pre filter and a dyno jet kit the kit has about 10 jet sizes the stage 1 and 2 set ups are the same except for jet sizes stage 2 says to install a 175 main jet we did that and it wouldnt start so i installed a 120 jet the factory jet is a 118 and it started idled fine and cruised fine in all gears but as soon as you gave it any more than 1/3 throttle it falls flat on its face it did this with the 112 jet the 116 jet the 120 jet the 155 jet and the 170jet and the 175 jet it wouldnt start with i got it to run good with the 112 jet with half of the k&n air filter taped up with duck tape which seemed like it needed more fuel thats when i started changing the jet size to the next one up each time and it idled fine and cruised fine but anything over 1/3 throttle and it fell on its face i tried all these sizes with the airbox lid on and off and taped the filter 1/3 of the way on the 116 jet and the 120 jet and when the 155 jet was in it i taped off 1/3 of the filter it bogged down a lot sooner like anywhere after 1/4 throttle and it was done

im kind of stumpped now and wondering if anybody has ever used dynojet atv jetkits before and if so have you run into this problem and what do i need to do to fix it the kit comes with all of these jet sizes
104
108
112
116
120
155
160
165
170
175
180
185

so that is where im at now any help would be appericated oh yea before the jet and filter was installed the bike ran great it only has about 20-25 hours on it i dont ride it that much

thanks john

 

well i would also think about moving the needle jet. and i don't know if it is on the 04 but my 06 has a idle ajustment screw that may need ajusted. when you open up the air that much cometimes you have to mess with more than just the main jet. just a thought. i am in the same boat kinda. my machine came with a 120 stock jet. i opend the the air box cover and put in a 118 and at about 75 percant of the throttle and higher it will cut out completly.

 

did you adjust the air fuel adjustment, and did you move the clip on the needle correctly... I havent had a problem with mine, i dont know what jet i used 165 or 175, but its the stage 2 full exhaust and no air box. i actually moved the clip on the needle down another space and got better results..... AZ Desert 1800 feet. hope that made sence, just start from scratch the directions are straight forward.

 

I'd throw that jet kit in the trash and go to the parts counter and get Original Keihin Jets. But it sure sounds like it's the needle jet.

 

i went back and double checked the main air jet plug that was good the nedle was in the correct install height with the spacers and everything was working fine , i just had some trash in the carb and it was acting up pulled it out cleaned it and popped it back in with the 112 jet and it ran great was a little lean so to changed it to the 116 jet and its liked that one a lot more and its not running lean any more so im good for now so thanks for your help

 

That sound small ,you should be about a 120(if you airbox lid is still on)