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twb503 · March 2nd, 2022, 09:31 AM

I’m sure this has been asked a million times, but I can’t seem to find anything that matches my situation 100%. So sorry if this is redundant;

My ‘09 250R SE had a Yoshimura exhaust and K&N air filter added by its previous owner. I have no idea if they messed with the carbs. But, when accelerating at WOT, the bike stops accelerating for like two seconds when it hits 9k, and very slowly climbs up until it reaches 10k, at which point it goes back to normal. If the throttle isn’t opened all the way, it’ll go past 9k easily. I don’t think it had this problem when I bought the bike, and I haven’t added anything to the bike. I think it got worse after I cleaned out the K&N air filter.

My theory is it’s running too lean. I tried running WOT around the same point with varying amounts of choke, but it still hesitates at 9k. I’m a little scared to mess with the carbs because I’m a total noob when it comes to carbs, and I’m afraid I’m going to mess something up. What should I do? Should I try and rejet the main jet, or something else?

March 2nd, 2022, 09:31 AM	#1
twb503 ninjette.org member Name: Conner Location: plano, tx Join Date: Mar 2022 Motorcycle(s): 2009 Kawasaki Ninja 250R Posts: 19	Bike hesitates around 9k RPM I’m sure this has been asked a million times, but I can’t seem to find anything that matches my situation 100%. So sorry if this is redundant; My ‘09 250R SE had a Yoshimura exhaust and K&N air filter added by its previous owner. I have no idea if they messed with the carbs. But, when accelerating at WOT, the bike stops accelerating for like two seconds when it hits 9k, and very slowly climbs up until it reaches 10k, at which point it goes back to normal. If the throttle isn’t opened all the way, it’ll go past 9k easily. I don’t think it had this problem when I bought the bike, and I haven’t added anything to the bike. I think it got worse after I cleaned out the K&N air filter. My theory is it’s running too lean. I tried running WOT around the same point with varying amounts of choke, but it still hesitates at 9k. I’m a little scared to mess with the carbs because I’m a total noob when it comes to carbs, and I’m afraid I’m going to mess something up. What should I do? Should I try and rejet the main jet, or something else?