i put a dynojet kit in my 02 auto vinson, it ran great all stock but got caught up in the what if i had more power dilema. stock i could pull wheelies if i put my feet on the back rack and could go to 62mph and stay there for miles. I put the kit in exactly as the instructions said, i'm under 1000 ft sea level so put the needle in notch 3 and jetted it and set the mixture screw to the instructions along with the slide spring. I must say the mid and top end gain was impressive but lost all my low end, wheelies where no longer an option, it would start hitting in the mid range much quicker and just want to go straight instead of up, also getting to 62mph was a whole lot quicker but i couldnt hold it there, it would hover at 62 for a moment then start sputtering and slow down to like 50-55 then all of a sudden come back to life and go straight back to 62 and do the same thing again. You guys have any suggestions on where to go from here tuning wise or are these jet kits crap?

 

I have always had good results from the jet kits I used. From your description I would wonder if you have a fuel flow problem? Is there a fuel filter on the machine that might need to be replaced? When you added the jet kit did you do a complete rebuild with all new gaskets and a thorough cleaning of all the tiny passages? Reset float levels? A quick clean will sometimes move tiny dirt particles out of hiding and into the tiny passages and cause a problem that was not there before. The recommended setting of the mixture screw is a starting point, normally some fine adjustment is needed after warm up to operating temp. Not sure if any of this is your problem just some things to consider....good luck