Bailey28

Member
May 1, 2005
32
0
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.

___________________
 

G. Gearloose

Pigment of ur imagination
Jul 24, 2000
709
0
You seem to be competent but more research here could have saved you some time.

Remember to reset the main for a 2mm soot ring when you make a change in taper or large changes in clip.

Best forget the a and most b-taper needles and move on to the Cs.

Also optimize the air screw, at running temp, after every other adjustment. Set for best off-idle torque, under load, NOT highest idle, else it can induce throttle-wicking bogs that you blame on other things. AS at Highest idle is the best way to dial in a bog or hesitation.
 

krazyinski

Member
Feb 2, 2006
100
0
G. Gearloose said:
Also optimize the air screw, at running temp, after every other adjustment. Set for best off-idle torque, under load, NOT highest idle, else it can induce throttle-wicking bogs that you blame on other things. AS at Highest idle is the best way to dial in a bog or hesitation.
could you explain this in a little more detail please?
 

G. Gearloose

Pigment of ur imagination
Jul 24, 2000
709
0
Sure.
the AS must be set to where the engine runs strongest off-idle. Do not read that as fastest rpm at idle, because that is a very weak, low-torque condition. Opening the throttle then further leans the mix...hence.flat spot, hesitation,etc.

The fastest-idle AS position is only a technique to coursly determine your selection of pilot jet. The AS has to be in a positional range where it actually is effective to the mixture; beyond a certain opening it is ineffective, too big a pilot will cause this...the mix just can't get lean enough.


Two methods for setting the AS... in all cases, modest 1/16 turns are required.
one is rolling on the throttle idle to 1/8 open, in third gear up a modest incline. When you get it, it will pull very strong off-idle.

second more unorthodox... butting the front wheel up a sharp incline, like a sloped rock or stump and optimize the AS to let the bike climb the obstical feathering the clutch and gas just a little off idle, to point of stall then recover the engine with the clutch. When the AS is set right the bike will climb like a goat and engine can be lugged down to its last revolution and still recover without stall; set wrong, the engine it will hit a minimum rpm that can't be revovered with clutch nor throttle and just die. Once set, the bike will have very good manners and good pull off-idle. Great for snotty, bony technical riding.
 
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Bailey28

Member
May 1, 2005
32
0
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.
 

Rhodester

Member
May 17, 2003
549
0
Bailey28, I had the same problem as you and did nearly exhaustive experimenting with jetting for 2 years to fix the bog problem. First you need to get a real pipe if you're going to get any significant performance out of the bike. An FMF -35 (woods) pipe will get you the smooth power you're looking for, but way more of it. With the pipe you'll need to run slightly leaner jetting than with the stock pipe.

You're not going to get rid of the off idle 4-stroking and have decent jetting anywhere else in the power range. It's the nature of the beast to 4-stroke at small throttle openings under a light load. To increase the needle straight section diameter to try to eliminate this won't work ( I know, I tried).

G Gearloose is right on setting up your air screw. It'll be in some from the highest idle setting to get the best response off of the bottom. If you end up in the 1 to 2 turns out range when this response is achieved then you know that you have the properly sized pilot jet. Less that 1 turn out go to the next richer pilot. More than 2 turns out go to the next leaner pilot.

Now for the nastiest part: the bog when you wick it (snap the throttle wide open when riding under a light load just off idle). You need a needle with a long straight section (this counteracts a rich condition at just off idle), a richer straight section diameter (but remember, the straight section is longer to avoid a too rich bottom end) and a steeper taper to a narrower tip ( to richen things up at or near WOT). WITH THE STOCK SLIDE I'd recommend a DEM. Why? Because the steeper tapered needles start the taper farther down the needle and have a richer tip (sends more of a vacuum signal to the main jet at WOT). This is the best way to get rid of that lean bog. If it's sill a little flat off the bottom when wicking it go 1 step richer on the main. If it's still a little flat on the bottom then put the air box lid back on and cover up those holes you drilled in it. This process WILL cure your problem. It took me 2 years to properly jet my bike AND not have the lean bog. The real answer for me could not be obtained with the air box lid off. And please note: I'm running a KDX200H just like yours ('95 and newer). Let us know how it goes.
 

G. Gearloose

Pigment of ur imagination
Jul 24, 2000
709
0
That BEL will be too fat around 1/4 throttle and the 45 pilot is too fat off-idle.
You cant use phat pilots for large diameter 1173/4 needle with those skinnier needles, its getting gas from everywhere. .. Your needle should be 38-40 but that won't help the 1/4 throttle one iota. The ccm and CCl will be dribbly fat at 1/4 throttle... .

I can see why the BEL works best, because it is the best of the bunch...you just have a bum bunch.

Try a cel and cek, each one will prefer a pilot 38-40

And stick with the 8-plugs else risk preignition.

Rhodester's experience with the lid is non-typical but I don't question his experience...he tested quite extensively and what worked for most didn't work for him, unfortunately. If we can avoid you stopping up the airflow that would be best. Like he sez you're stock pipe is a whole nother variable, but since your not looking for max power see what you can do with it...
 

Rhodester

Member
May 17, 2003
549
0
I think I've seen a few other 200H riders that have had my problem, but you're right, G., it is on the rare side. I don't think I've ever heard of a 220 with the same lean hesitation/bog problem. I also hope that you won't have to put the lid back on to fix the problem, but if it's severe enough to not go away w/o the lid you'll still run much more powerfully properly jetted WITH the lid. I had to run a 168 main jet and 1 1/4 out on the air screw with a 42 pilot to get rid of the hesitation/flat spot. As you can imagine it screwed up everything else having to be that rich. The lid back on was a much better (and more powerful) solution than super rich jetting.

I'd recommend the following "C" needles: CEM with a #5 slide (stock slide), CEL with a #6 slide, and a CEK with a #7 slide (more correctly speaking, throttle valve).
For "D" needles (a better solution for the lean hesitation/bog problem): DEM with a #5 slide, DEL with a #6 slide, and a DEK with a #7 slide (which is the set up I use). Good luck.
 

m0rie

Member
Nov 18, 2002
469
0
I'll second the D needle choice for electric smooth power. DEM (or DEK after you have RB work over your carb) in the #4 slot will make an amazing difference in the snotty condition department.
 

Bailey28

Member
May 1, 2005
32
0
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.
 
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