throttle responce 300 fourtrax

A bit of hesitation is inherent in the design. It's hard to get instant throttle response with a carb, but it shouldn't be literally 2 seconds either lol. A well tuned carb will have minimal hesitation, sport carbs have an accelerator pump on them to squirt extra fuel when you snap the throttle, helping throttle response. Now, you CAN with some mods switch to a 300EX carb, or you can try and improve on what you have. Cutting a few coils off the carb spring can help, too many can hurt too though and once they are cut you can't add them back. Mind you it's only $7 for a new spring. Can also drill the empty hole in the slide a bit bigger, I haven't looked at one out of a 300 lately, probably go 1/8" or so I think that's the norm. Just some ideas for you, of course do your research before committing to anything don't just take my word for it.