Jetting in Florida

After I got the suspension dialed in thanks to the help of this great board, I wanted to get the motor more crisp. I live in Gainesville, 150 feet above sea level.

Here is what I did so far---

2005 200 stock everything, too rich everywhere. All testing done with Chevron 93 pump gas and Yamalube 2R 32:1

Rode the bike with a new 155 main and 45 pilot 2.5 turns out, removed snorkel but left the lid on with no additional holes.

Ran ok, still 4 stroked off idle and was generally sluggish so I ordered new needles from Sudco. CCM, CCL, BEM, BEL, AEL. I ran the 155 main but changed the pilot to a 42.

I ran the bike in the same conditions, fairly humid, 75 degree day. The BEM on the third clip was good until the bike warmed up, then it just four stroked, smoked and was weak throughout the whole range. I changed to the 1st clip and the bike responded better. Pilot was 3 out by this time.

I noticed that with the 42 pilot and the "L" needles, the bike ran waaay too rich and would not even powerband after fully warming it up. The best needle for the day was the BEM, top clip 3 out on the pilot.

I bought a 40 pilot on the way home and tried again this afternoon. The best I got today was :

152 main, 40 pilot, BEM 4th clip, 10 3/8" holes in the airbox lid, float height at 17mm, pilot screw out 2/3. I tried this combo once with the needle at clip one and clip 2 position, but bogged horribly in the midrange when whacking open the throttle in 2nd and 3rd, going walking speed. I tried the combo with the airbox lid off totally, which made the very bottom end real snappy part throttle with NO four stroking, but made the bike bog even worse in the whack test. Roll on was good if I rolled at a "medium" pace. Blipping also bogged bad. Lean bog, booowaaahh sound. I finally replaced the airbox lid and raised the needle to the 4th clip. The bike responded a lot better to the whack test in 3rd gear from near walking speed. I stopped here, as it got dark. I also ran a BR7ES plug for the entire test this day. Pulled it and it is still dark and oily like the 8 was. Top end was fine and pulled strong.


Hypothesis: I think that the bike likes a real lean bottom idle to 1/8th setting, but as soon as you whack the throttle, it needs to be rich to avoid a bog. I will try the BEL needle, which may be rich enough to avoid that bog when whacking the throttle off the bottom. I want to keep the 40 pilot in it for now and maybe add more airbox holes. I think I can get the bottom to not four stroke if it is lean enough. It's almost like the bike needs an accelerator pump! Any input would be appreciated. I know this will change a bit when I dump the stock pipe.

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Gearloose, thanks for the airscrew info and the info you wrote in a way earlier post about the airbox lid. I deducted from you airbox post that the lid just makes it richer everywhere, but disrupts the pressure and air flow to the point that it negatively affects carb operation as a whole.

I will toss the lid all together and try a 45 pilot BEL needle 3rd clip, 1 1/2 out on the air screw and a 155 main. 7 plug, and go from there. I DID have the super responsive tight snappy bottom end just once when I tossed the lid on one of the tests. I put the lid back after I got the major whack bog. I think the straight diameter of the needle will have the greatest effect on the whack-bog test along with optomization of the air screw. Air filter is also clean. If I can get the bike to not bog while wacking it open with the lid off, I can get the bottom to be more crisp. I can't afford an aftermarket pipe right now, but I may try the Fredette torque ring spacer and a KX125 reed spacer for more bottom. I think the bike can do it.

I will try the B tapers then the CCM and CCL that I bought. I wanted a more "electric" response from the motor that will make it easier to ride. I came off of a ported 04 YZ250 that hit so hard the crossbar would try to take your teeth out! I am much faster on the KDX in everything I ride vs. the YZ. I am very happy with the KDX. Don't get me wrong, the YZ was a great bike, but it's for someone who is much faster than I. I want smooth electric = faster and more fun.

Awesome info guys, this sums up much of the information I have been searching on for weeks now.


I will try the D tapers after I go through the C's, I have to say though that I got NO wick open bog with the airbox lid on and with the B or A tapers. The bike did run really rich and the hotter it got, the worse it ran. This is my 10th bike, and probably the 9th I've had a chance to jet correctly.

With the lid on, I actually enjoyed the AEL as it was damn electric! Still muddy on the bottom, but if you cleaned it out every now and then it would respond quite good. I could ride up the steepest hardpacked hills while keeping the front tire floating just inches above the ground in 3rd gear, modulating the throttle like a rheostat! I am not after "max" power, I can give up one or two if it means super smooth seamless response from the bottom up. I will try a Pro Circuit platinum 2 or a FMF woods gnarly bend in the near future. These pipes with a Fredette torque ring spacer and a 5mm KX125 reed spacer will hopefully be a recipe for a wild bottom/mid motor. I will go back to the 8 plug for safety's sake.

Each bike is different, and know the altitude and weather make a difference too. I ride mostly in the 55 to 85 degree range at sea level. Anyone want to trade or sell me a D taper for cheap? Got a CCL because they were out of CEL's, I read that the CCL top clip is like the CEL on the third clip. CCM is just leaner in the straight portion.