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Yet Another Jetting Question
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Posted by: Ball

Where would be a good place to start to rejet my KFX with no airbox lid (needle position/jets).I am @ 200-300 ft above sea level w/ only slight modification to the stock exhaust. Any help would be appreciated.

Posted by: Billdog350

I can't tell you any stock jet #'s. My dealer is a PITA to order individual jets from. However I'm about 200-300 ft above sea level here in CT and when I removed my lid I went with the exact reccomendations of Dynojet. DJ needle on 3rd clip and a 146 Main Jet with the idle screw 3.5 turns out. Runs, starts and idles perfectly. The 146 is a little fat for the stock pipe, but if you remove the endcap its MUCH better. They say to go 150 if you run an aftermarket exhaust with the lid removed. I priced out the individual jets and it would cost me more to buy the various jets and still not be able to adjust my needle. The DJ kit is about $50-60 and allows you to fine tune your needle setting (mid range) where the stock doesn't. Also, DJ took the time to dyno tune their suggestions so they work 95% of the time out of the box, with no need to keep fiddling with it. Considering how hard it is to get to the z400 carb and change the jets in it...I would go with the DJ kit and do it once...rather than have to fiddle with Mikuni jets a few times to get it right.....

Posted by: Ball

Thanks for all the info, I really appreciate it. BTW, I had picked up a package deal on Ebay a while back that included a stock carb, Dyno Jet kit w/ needle, and Throttle cables for twist and thumb for $55. So I will be using the Dyno Jet kit. Thanks again for the info!