KDX 250 Remove air box lid Questions

I would definately recomend tossing the air box lid. Rejetting on this bike is necessary. The stock jetting(if you're still running it) is way too rich. I run a 160/162 main and a 48 pilot.

In addition to leaner jetting, you should be able to use a BR7ES in a trail ridden KDX250. Me and my friend used that plug in our KDX250's for several years.

I can't remember the exact jetting we used (at around 4,000 feet for most trails), but I think it was the leanest optional pilot (the lowest #) and leanest needle (the highest number) shown in the owner's manual and at www.buykawasaki.com The bike also benefits from a leaner slide with 1mm more cutaway. This is a little pricey - some people grind 1mm from the bottom of the stock slide.

You can use a high compression head gasket from an '88 KX250 - some other year KX250's (I think up to '90 or '91) can also be used, but some years KX have more than one thickness available. Get the THIN one and use premium pump fuel.

The bike is VERY rich stock - it will run much better after jetting. After you get the motor dialed in, the bike runs well, with excellent bottom end power and a very heavy flywheel. No need for a flywheel weight, that's for sure.

The stock pipe is very heavy. After rejetting, the stock pipe has a fairly abrupt low-mid hit. The aftermarket FMF pipe will smooth or eliminate the hit and give more power and revs on top.

I enjoyed my 250 very much - it was not well dialed in from the factory (especially the jetting and forks) but with a little tuning it is a good bike!

On the 91-94 KDX250s, you may not want to toss the lid off. The regulator and recitifier sit on the airbox lid. You would relocate the, but it is easier to remove the HUGE baffle from the top of the lid. That will open up the breathing a lot.

With, Vforce 2 reeds, porting and Dynoport pipe this is my jetting at lik 500 feet:

Pilot: 38
Main: 160
Needle: stock, 3rd clip from the top.
Slide: #5 slide (stock is #6)