Dyno jet.......they are shitttty to me. They had me cutting my airbox lid up & some of everything & it still didnt run right. They got this crazy ass adapter that connects with the main jet cause the jet they sent dont screw into my carb. like it suppose to. So I said I'm just taking the hold jet kit out & except that it was a loss of money.So my cousin requested I go buy some jet from Jets R US & they worked fine, but I cant get it to run right & get my spark plug the light brown color it should be. It runs perfectly mid range to top side(1/2, 3/4, & full throttle). It will idle fine but at 1/8, 1/4 throttle it stumbles badly til it all of a sudden catches & it ok. It does it everytime I come to a complete stop then try to take off again.