KDXRIDER.NET

Ive been experiencing some bogs lately. When I am sitting and idling, and I go WOT, it bogs until up to speed. Also when im slowly going up a steep hill and i give it more throttle, it bogs as if i were in a gear too high. I changed from stock gets to 45/155 and that it when it started. Is this too lean or too rich?

what bike and mods?

what needle?

what clip position?

Even if your jet selection is correct, the air screw is the prime suspect.

Adjusting it to 'high idle' as is often recommended is exactly wrong.

Assuming your pilot to be correct (if it's not, no AS adjustment will resolve it), adjust the AS using throttle response as a guide.

Roughly: One gear up from where you should be (2nd..slow walk speed) crack the throttle to about 1/2. Adjust the AS until the bog is gone. If you can't get it gone, the pilot isn't right.

Allow the bike to run for a bit after each adjustment. Immediately testing throttle response after you have yanked the AS around a 1/4 turn will get you nowhere.

No KDX200 is going to snap/pull like a larger bore bike, but the engine should certainly respond immediately.

With an unmodified carb, the old rule of thumb of, '2.5 or more out = too rich a pilot' is pretty good.

With a modified (RB) carb 2.5 +/- is right where you want to be. The 'old rule' does not apply to a modified carb.

..Thank You Ron!

2006 KDX200, stock needle, middle clip position. You say that the airscrew is the prime suspect. From my understanding, that only effects 0-1/4 of the throttle opening. My problems are at WOT. Does the aircrew work when the engine is caught up to 1/4 opening? Or when the twist throttle is twisted past 1/4?

awoodman wrote:When I am sitting and idling..

Sorry. I didn't realize the sitting and idling part was @WOT.

Re: Does the air(s)crew work when the engine is caught up to 1/4 opening?

My head hurts....

Not to be pedantic..but something is being missed.

If you're sitting and idling, you are not WOT, correct? Correct.

If you are changing from one circuit to another, which you are, the different carb circuits will come into play, overlapping on the way 'up'. How well they interact, how 'seamlessly' they seem to overlap is directly related to the individual setups of each circuit.

The 'smaller' circuits (pilot and the associated passages for example) work with 'smaller' airflows. There is a reason that circuit is not the size of the main..which feeds the 35mm bore at full throat. If you wick the throttle from idle to WOT, the carb does not instantaneously 'switch' to all main jet. There isn't enough air flowing at the instant you twist to activate the main jet circuit.

Is that better?

The fact that the engine works at all in that case (without an accelerator pump) is quite a marvel in the first place.

Yeah, that helps, but it wasnt like this when i first got the mike and messed with the jetting, so i dont know if im too lean or too rich.

How are your reeds?

Neither do I know that (whether you are rich or lean). 45/155 is not likely too lean. It could be. Many factors fit into the jetting equation.

That's for you to figure out using standard carb tuning methods.

The chances of a KDX being too lean are small. If you run in the sand at sea level with no airbox lid, a pipe, a bored PWK and you're running a 40/152 jetset (KDX200), frankly, you're a moron, (I'm not saying 'you' personally obviously) and you WILL blow up your bike.

Back to overlap. You changed parts of the sequence. The rest of the sequence must be adjusted to match.

Adjust the air screw.

I think I hear an echo.....

strider80 wrote:How are your reeds?

Havent checked them, but the bike is like new, so im assuming they're fine. No hard starting.

---------"The chances of a KDX being too lean are small. If you run in the sand at sea level with no airbox lid, a pipe, a bored PWK and you're running a 40/152 jetset (KDX200), frankly, you're a moron, (I'm not saying 'you' personally obviously) and you WILL blow up your bike."-------------

CC, I had the RB mods done to my carb with the understanding that I run in the Florida sand, at sea level, no airbox lid, Pro Circuit Plat II, bored PWK, and a 40/152/CEK-4/SSS at 2 9/16, 05 200, installed by Ron at his recommendation.

Is this going to blow up??? I don't think so, it runs better than ever, and with the home made reed spacer will flat make me **** my pants out of every corner. Wide ratio trans?? I don't notice the spacing as much if at all now... 1st gear with the CEK-4 is now almost unuseable, I may try the DEK-4 for more control. It has been out four times, Yamalube 2R 32:1 93 Octane pump in it, plug is tan, dry and minimal spooge coming out the back. Oh, and a twin air filter has replaced the stocker.

Again it RUNS GREAT!! I'm glad you're happy for me.... I could not ask for a better running 200, it does everything NOW when you hit the gas...

Yours truly,

The MORON who is going to blow his bike up

The sand in your neck-o-the-woods isn't at all the same as the sand here, for starters. There are probably about a brazillion places at any west coast riding area that are higher than any place in the entire state of Florida. And to GET there, you gotta go UP!

How's this? If I am stupid enough to run at the coast on the dunes with a 40/152 jetset I will have no one to cry to when my bike blows up!'

And it will. Guar-an-dam-teed.

Heck, I've lean-roll stuck my bike with a 40/150 at 4000'@ (not in the sand)

The real point to be learned is....what? Every bike is different, as is every rider. Tune YOUR bike to run the way YOU ride it WHERE you ride it, WHEN you ride it there, and everybody will be happy.

Jet your bike by mail (or email...or post) and you will get what you paid for.

You bet I'm happy for you!

Next time you're out this-a-way, we'll go riding. Bring some jets!!

Your symtoms sound like what I had some time ago. It was a lean bog from my needle clip set too lean. Carvr diagnosed it. From a stop, I would snap the throttle Wide open and on a slight up hill grade. It would almost die!! Bumped the needle one richer and she came back to where I expected it; snap the throttle and instant wheelie.
Remember, if you are not sure if you are too rich or too lean, adjust to richer and you will know for sure which direction to go without risking damage to anything other than a wet or fouled plug.

I am under the impression that jetting needed to be leaned when going higher in altitude.

My guess is that with RB's divider plate mod, jetting is numerically leaner because the divider plate makes the jets act "richer" ie. a 40 acts like a 42/45 a 42 acts like a 45/48 etc.

So if I came to your neck of the woods, and the temp was around say, 70-80F, at 4000+ feet I would bring my 35 and 38 pilot jets, drop the needle one step and install a 150 main. 40F? I would leave it as it is, then adjust the AS.

In FL if and when it gets to be 45-50F? 42/155 for sure at sea level.

Dunes: Are you talking 6th gear, wide open for 5 minutes in 10X powdered sugar? We don't have that luxury around here. If that were the case, maybe a 155/158 would keep the 'ol peeston safe. We have sandy forest trails and sand tracks, WOT 5-10 seconds max before you run into something...

Lean stick at 4000' 40/150? Me thinks that the Fredette porting/ US chrome swiss cheese job had something to do with that...

Again, it is all fun and games until someone's eye gets poked out

thanks guys, when i get a few minutes, ill mes with it and see what i can do.