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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

Testing Image

James’ KLR

“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.

See-
http://www.pbase.com/jdjetting1/high_elevation_jetting

The KLR650 jet kit is listed on our website at-
http://www.jdjetting.com/xcart/product.php?productid=106&cat=0&page=1&featured

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.

Thanks,
James
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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.









continued...
 

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Discussion Starter #2
JD Jet kit installation/airbox mod- part two

4. Loosen both manifold clamps almost to the end. I was warned about breaking the plastic choke piece, but I suppose I got lucky. I tried to create as much slack in the cable as I could.

5. Rotate the top of the carburetor toward you and remove the 4 screws. Pull the top of the carb off. Remove the diaphragm with slide and needle.








6. Drill the smaller hole in the slide. Not sure what size my bit was, came with the kit and my eyes are too old. Make sure to clean up all metal shavings.



Here’s a picture of the different needles for comparison for those of you who can make any sense of it. Main differences that I could see is the sharp taper on the stock & the adjustment grooves for clip on the JD needles.




7. Reassemble with any new parts. KLX needle, washers, etc. I can’t speak to the amount of washers or KLX needle- didn’t use them.

8. Rotate the carburetor back into upright position. Remove the drain plug at the bottom and drain fuel. Replace the drain screw when complete.

9. Carefully remove the carburetor from the intake manifold and then from the rear boot. Be careful not to break the plastic choke cable end. Remove the float bowl from the bottom of the carburetor. I recommend replacing the Phillips head screws with the upgraded allen head type. I was able to remove the carburetor from the manifold & boot with crash bars in place, but it made things more difficult.



10. Remove the main jet and replace with new jet. Reinstall float bowl



11. Time to drill out the fuel mixture plug. Locate the small metal plug- not the brass plug next to the fuel screw. Drill carefully- only enough to get through the plug. Try not to damage the brass screw under the plug. The plug in my carb slipped out as I drilled. If you end up with a hole in the plug, use a sheet metal screw to insert into the hole and pull it out with pliers.



12. Gently turn the screw all the way in. Adjust the screw back out to the correct amount for your set of changes. I backed it out 2 ¼ turns and it worked perfectly with my set up.

13. Replace the carburetor- don’t get violent with the intake manifold or air boot. Take your time, it will go back in.

14. Reinstall seat, panels and gas tank. I found it easiest to connect the small fuel petcock vacuum hose while the tank was sitting in place, but not yet bolted in. Could be a better way, but it worked for me.

Anyway, that's more or less the way that I remember it. Sorry if I let any parts out. Again, I'm not great with this stuff and I didn't find it too difficult. The bike runs great and definitely has lots more pep. Hope this helps someone get the job done.
 

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Hi Zin, got the Jet kit, now I'd like to know where you picked up those uni airbox filters and the uni foam. Can I pick them up locally?
 

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Nicely done, Dave!
 

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I used the JD kit in my DRZ E model with pumper carb. I didn't know he made one for the KLR vacuum carb.
I'm shocked how the needles don't look like needles at all.

Nice writeup with the pics!
 

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Great Write Up!! I just ordered the JD Jet Kit and the Uni Inserts for my airbox and was curious if this will void my warranty? I only have 123 miles on the bike and Iam still breaking it in (keeping it under 4K RPM) but I am noticing a surge around 4K RPM and it seems like what my Yamaha Raptor 700 was doing before I changed the MAP on the computer/Power Commander, it was also really lean from the factory, the MAP and air box mods made a huge difference in the throttle, alot smoother and snappier than stock and my pipes dont glow as quick or as bright as they used to. Iam thinking about doing a slip on with the jet kit and air box mods on my KLR and normally ride under a 1000 feet and no higher than 3500 feet here in West Virginia and was wondering which Jet would be best to use? Thanks Again for the Instructions and hard work you've done here, I really appreciate it..
 

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Mountaineer,
Glad that the info helped. Your kit will contain good instructions for jetting/set up combinations for various alts & such. James will freely give assistance and advice on setting up the various jet/need configurations- don't hesitate to shoot him a question.
 

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I would stress the fact that anyone that plans on working on their carb order some stainless steel hex head screws to replace them the stock screws with. ALSO I had to call JD's customer service and they helped me get past that brain fart I had, besides the screws being tough to get out of the float bowl, its was a fairly easy install. I had to use vise-grips to get 2 screws out and the carb was a PITA to get on and off. I rode the bike with the exhaust only a few miles then today a few miles with the JD Jet Kit and air box modes and the Jet Kit and air boxes modes were the biggest improvement. Much better throttle response! Thanks Again for posting..
 

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I recommend KLX kit from Eagle Mike, it comes with a few different jets, a KLX needle with clip and collar, also he throws in a set of stainless steel bolts to replace the crap bolts that are stock.....a good kit for a great price.:13:
 

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Nice job. I did regular KLX needle, larger pilot jet, and snorkel removal on the Gen2. Runs like a champ. A little lower MPG is the only downside.
 

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Ancient thread but since it's been resurrected; I've heard good things about the JD jet kit (Unlike the DJ - DynoJet kit which is WAY too rich). I use the KLX kit and from people that have used both, they are both similar in functionality.

What I find interesting in this old thread is that JD's dyno results almost EXACTLY match KLR Chris' results ( https://www.klrchris.com/) with a very similar, yet slightly different approach.

It seems like stock is about 33-34 hp.

- Proper jetting and airbox mods get you to 36-37 or about a 2-3hp gain

- a good silencer can give you another 3-ish hp or so up to the 40hp mark. Both used an FMF silencer; Chris says he used an FMF Power Core 4, I didn't see where JD says exactly what model he used. I've used the FMF Q4 with good results.

The only other thing I'd add to the original post is - don't bother with the little 1" filters in the airbox holes; they do nothing useful and add maintenance and restriction. You don't need any other filter than the main one.

Dave
 
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