It was suggested to me to come here as there is a good deal of (accurate) info available. I have a '98 ZX-9 that I've converted to a naked... all panels have been removed. The air ducts on both sides of the tank have velocity stacks feeding air into the airbox. The breather tube that was on the orginal fairing/duct opening it positioned by the new headlight... it's still able to breath.

The is a pronounced hesitation bewteen 4-5K. If given more gas the engine will hesutate for a second, then come alive. The powerband is also fairly choppy.

There is some articles indicating that I may have a pressure issue in the airbox caused by some of the ducting changes? I may also need to do some re-jetting (very likely)?

What suggestions or advice can anyone offer??

Thank You!!

JB

 

That is just off idle throttle load in that range and generally the needle height/taper/spring is the culprit. Have you tried keeping the choke slightly on to see how the bike ran? Just an opinion since you have done extensive modifications to your ride. Good luck and Welcome to KF

 

Thanks D-19!!

http://www.cycleworld.com/motorcycle...ighter_project

JB

 

It has something to do with the fuel pump and the pressure, by removing the front air ducts you take that pressure away in that causing hesitation from here you could either go two ways recalibrate the carbs,needles or you could go the cheap route watch this video for a homemade fix http://www.youtube.com/watch?v=KtISwbsv-yc&sns=em I hope this works out for you

 

Thanks for the link wheel408

 

Thanks for the vid/link... it's given me some things to think about/consider. I have somecity stacks sticking out from where the old ducting went into tank/airbox... so I would think the pressure would chamge that much????

Thanks!!

JB

 

Hey, that's good!
That's got me thinking about my old '95. Mine's got larger rejetted carbs and gets on it (surprisingly well) up to about 100-105mph. Then it just hits a WALL. I still have at least a 1/4 turn of throttle, but it ain't happenin'. I suspected some air pressure issue (but have honestly been too lazy to pull it all apart.) You're putting ideas in my head...........
Thanks!