MarkNet - KLR650 : Carburetor Air Mixture Adjustment

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This is a hobby website dedicated to the Kawasaki KLR650 motorcycle. I make no claim concerning the accuracy of the procedures, nor do I guarantee the success of any work done using them. All users of the material found here are advised that there is no real or implied warranty associated in any way with the website content, and that all content available here is for use at your own risk.

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CARBURETOR AIR MIXTURE ADJUSTMENT

This is the side view of my KLR650 carb. Everything can be done from this perspective with 4 tools

Notice the hose clamp holding the inlet side of the carb to the rubber intake. The clamp was formerly turned so the screw was facing upward toward the gas tank, so reaching it was not gonna happen. After this procedure is over, you'll do yourself a favor on future projects by setting it to face out, as shown below.

Now loosen the other clamp, and remove the big bright screw holding the throttle linkage on. Notice the chewed head. I dream of replacing every screw on this bike with a decent grade allen head.

Detach the cables by rotating untill they mate with the slot and push them under the gas tank and out of the way. Now all you have to do is rotate the entire carb counter-clockwise until you can see the plug.

This is the part of the carb you’re looking for. The plug is inside this tube, and is roughly ¼” by ¼.” I drilled a pilot hole with a much smaller bit first so as not to cause any damage. After that, l used a ¼” bit and the plug spun out easily. The plug is aluminum, so drilling is easy. GO SLOW as the adjustment screw is delicate and you wouldn’t want to jam a spinning drill bit into it.

For the adjustment, turn the screw all the way in. Don't gorilla hand it, just lightly turn to a full stop. Then, with a common screwdriver, back that air/fuel screw out 3/4 to 1 full turn and put it all back together. It should be noted that worked well for my 2001 KLR; you may need to tweak & adjust for your specific bike.

(On my bike, the original factory setting was 2 1/2 turns.)

The only hard part is holding the carb on an angle as the intake tubes do resist. Removing them seemed to be too much work so I left them. But if yours are already off then now is a good time to do this.

While I was tinkering under the left side cover that day, I found this rubber tube thingy in the air filter housing. From what I can deduce, it silences the air box and restricts flow as this is the only way for air to enter the air box. Since I had just increased fuel, why not increase air. Pull it out go for another ride. This, in combination with the richer mix, made a big difference in drivability, power and sound. Not sure about milage yet though. Best FREE mod ever.