I have a 92 250x with a uni air filter and holes in the air box it has a home made head pipe that is larger than stock and the stock silencer, I just put a new weisco piston in it and now im having a little problem with throttle responce. i can be putting down the road in any gear and when i open the throttle up it has about a 2 to 3 second hesitation befor it takes off. could this be a jetting problem? i believe it still has the stock jet, (what ever size that may be)in it. can some one please help me out. Oh ya, the new piston is slightly bigger than the stock one i replaced. I believe the guy said it was like .020 larger than stock. does that sound right? well anyways, I hope someone can help. thanks

 

You've got a bigger head pipe,bigger piston,holes in the air box,and you HAVEN'T rejetted? you are lucky you haven't burnt that new piston already. Just as a guess,I would go up 3 sizes on the main and see how it runs on the top end,if it skips,drop down one size until it runs clean,if not,go up one size until it does skip,then back one.

 

THANKS FOR YOUR HELP. ILL GIVE IT A TRY.

 

yea we have a 250x that was bore 20 over and it had the same problem, but I think one of the problems was the guy who bored it had messed it up, but I don't think that was the problem because after we checked the carb, we put a bigger jet in it and we noticed it was leaking a bit of gas from the seals on it and it was sucking in air, you might also want to check where the carb hooks onto the air box, because sometimes its hard to get back on and it tends to slip off sometimes if you don't do it right

 

did the new jet help? or was it just the boot between the carb and the air box?
what size jet did you put in it. and how does it run now?
I havent tried the jet yet because i dont know what size to get.