03 kx250 jetting help

[droyz]

I just bought an 03 kx250 and I'm trying to get rid of the hole and some of the hit from low to mid in the powerband. Does anyone know how to cross reference a NAFW needle #16187-0014 for a DDK or similar single taper needle ? I heard this will help with the hit some. I also want to try adding the 1mm powervalve shim. TeamGreen only shows the powervalve itself but not how to get to it are their any instructions online that show how to do this ? I heard you need to remove the right-side engine cover.

 

[Lissa]

Purchase a Service Manual for your bike. It'll come in handy for disassembling the powervalve as well as doing maintence like rebuilds. If I remember right Kawasaki offers a optional thicker head gasket that'll lower the compression a notch. That'll smooth out the power delivery and the hit. It's a very cheap fix. Another thing to try if you find the hit a little on the hard side is to try a flywheel weight. It'll slow done the pipey'ness of this motor and make riding the hit more controlable. You could also experiment with final gear ratios. Is the gearing stock? I usually go up two teeth on the rear sprocket to put the meat of the power a little lower in each gear. If the current gearing is not stock you could reverting back to stock to see if that helps. Or you could go a tooth or two smaller on the rear if the bike still hits too hard and too soon. Stock gearing is 13 Fr-49 Rr. A MotoTassanari V-Force is also good at smoothing the hit out. You could also try changing the expansion chamber on this bike. The stock one (my personal preference) hits the hardest and is one of pipey'est of the pipes I've tried. The Pro Circuit Works pipe is more of top-end pipe and eradicates the bottom-mid-range hit (may be just what your looking for?). The FMF SST smooths out the bottom-mid range hit and seems to move it upto the upper mid-range instead. The FMF Gnarly seemed very similar to stock and is very pipey. I hope some of this has helped. I found the jetting stock to be very close, I only needed to go from 168 main to a 165 to clean it up.

 

[droyz]

Thanks Lisa, your input definitely helps. A shop manual is a must I was going to put off buying one until it came time to do the topend but I think I'll go ahead and get it now. I know the jetting is off for both the pilot and needle where I'm at. I started it today in 40 degree temps no choke on the 1st kick and the bike idled without giving gas. Jetting is stock so I'm thinking leaner pilot and needle. I would like to try a single taper needle as I know it helps smooth the transition on KTM's but I don't know what is compatible for the KX. I have no problem with the amount of power available, actually it is lacking a little in power dept. especialy on top it's the little hole between low and mid that shows up on steep jump faces right out of turns that I need to fix. I'll try a bigger 50t sprocket
also but my jetting needs help any ideas ?

 

[bigred455]

On the 03 kx 250,when the temperature starts to drop in the high 40's the needle is too lean.Go for the 3rd clip, and you can bet your pilot will richen up from the needle position,so adjust that also. I ported my motor and bought the squish down,stock compression,I am running AV GAS,but even on a stock motor with pump fuel your needle will still be too lean in the 40's. Stock reeds,Boyesen reeds,carbon tech reeds, it will still run lean.

Speaking of reeds,after a good few rides depending how you ride, the kx reeds will not hold up. The carbon tech reeds are outstanding, enough said!!!!!!