I was asked to re-post so that this guide could be stickied. Glad people found it helpful.
I chose to go with a JD Jetting kit following excellent results on my dirt bikes. I realize that this flies in the face of cheapness, but I wanted to stick with what I knew.
So, with some help from Tom Schmitz (Thanks Tom!) I set out to install the jet kit and mod the airbox. The kit came with an assortment of 5 jets, high & low alt needles, drill bit for slide, and a nice set of instructions. I also cut five 1" holes in the airbox and installed Uni Airbox vent filters in the holes. I also bought some UNI foam sheets to begin making a light filter for where the snorkel used to live. Did the mixture adjustment and put everything back together. Bike started right up and ran great.
Ok, here goes…. This is my first attempt at offering any kind of assistance to anyone. For that matter, this was the first time that I’ve torn into the KLR carburetor. So, I’m definitely no expert and you can consider yourself warned. This is my best attempt at lending a hand, so take it or leave it.
I should start by giving some credit. Tom Schmitz gave me some great advice and help before I started and I read his posts a bunch.
The printed instructions from JD Jetting were excellent and I plan to use a bunch of that information in this post.
Since the install, I contacted James from JD Jetting and he gave me some information to share regarding testing. Really nice guy! Quick with assistance and information. He generally handles jetting for race bikes exclusively, but he said that the KLR and DRZ were his two exceptions and it turns out he rides a Gen 2 KLR. www.jdjetting.com
Check out the links:
Dyno tests for various configurations
High Elevation test
“We have an exceptional jet kit in the Kawasaki KLR650, but there are very few KLR650 owners that know about JDJetting and the extra effort we put into jet kit development. The jet kit needles are custom machined with more tapers than standard needles to give extra performance and more consistent jetting over a broad range of conditions. The bikes are dyno tested and ridden in both off-road and on-road conditions to evaluate results. These aren't like other brands of jet kits that are just using a quick approach with less development, or those that are simply re-branded kits made by another supplier. I ride from sea level to high elevations in Colorado to see the differences that elevations make, and incorporate these factors into the jet kits.
The KLR650 jet kit is listed on our website at-
There are only a few models that are not race oriented bikes that I've chosen to develop jet kits for, and the KLR650 and DRZ400S are on that short list.
So before you tell me about washers, old chewing gum, and bailing twine…I know ----- no need for that debate. I went with a jet kit because I had used JD kits before and the results were great. I was also a bit nervous about trying this on my own and I knew that the instructions would be clear and that he would pick up the phone if I needed help.
I wanted to contribute something back to the site and reciprocate for all of the great tips that I have received since I bought my bike. I figured that the procedures are pretty much the same as the 22 cent mod- I just moved the needle clip instead of adding washers. You cheapsters will have to use your imaginations.
Anyway, hope this helps somebody like me who is nervous about trying this stuff. It wasn’t too hard and I’m glad that I did it.
Here's the kit:
1. Remove the side panels, seat and gas tank. Make sure the fuel petcock is turned off.
2. Remove the snorkel from the top of the airbox. Mine took some prying, but it eventually popped out.
3. I chose to drill 1” holes into the airbox using a hole saw. I wanted to install the UNI airbox filtered vents and to be able to easily plug the holes again if I needed undo my attempt at this project. Cut any way you like, but don’t go past the 4” mark on the long side of the L shape in the airbox (see picture). I covered the intake screen with a rag to prevent any debris from getting in. Make sure that you clean up the edges of the holes and thoroughly clean the plastic bits from the airbox when you’re through.