hi i have a 07 ex250 and i just got a muzzy exhaust installed a 6 months ago.... it ran fine, then i got a jet kit installed last month.... ever since then, the bike has been hesitating at steady throttle in any gear and at any mph.... i recently installed a K&N Air filter yesterday, however when i took out the factory air filter/frames, there was a puddle of oil in the air box..... i cleaned it up and put everything back together..... then i test drove it and still hesitates...... it seems as though, as long as i have the throttle holding, it will hesitate, but as soon as I accelerate, it will be smooth sailing! this really bothers me when im cruising on the highway going 60mph and it hesitates,feels like misfire, bogs down..... i bought back to the place who installed the jet kit twice and they said they fixed the problem twice...... if you guys have any advice, please help! thank you for your time.....
Andy

 

Hey Andy, welcome to the forums, as far as the bike goes, there should be someone on here soon that will have an answer.

 

I have a '94 and mine does the same thing at around 6-7 1/2 k RPM. If i give it harder acceleration its fine but the sputtering half way thru the rpm range is annoying when cruising, to say the least. I recently changed out the plugs and installed a new air filter. I have the Yoshi pipes and muffler. I'm curious to find some advice on this problem also.

 

so do you think i should change the plugs? i already installed a drop in K&N air filter...... how are the plugs suppose to look like? i have had the bike for alittle over a year now, so i don't know if i should change plugs...... thank you for your time.........

 

Check this link on spark plugs (I've seen others like this one). This could help. Good luck.

http://www.totalmotorcycle.com/maint...sparkplugs.htm