KDXRIDER.NET

Hey guys,

I took my 2006 KDX 200 out for a short run (second time I've driven it) yesterday and I noticed a "bogging" feeling. It felt like the first and second gears were almost useless, feeling a "power hit" when shifting into third. Cracking the throttle open didn't do much and the bike just felt like it needed to shift (almost like it was revving but not accelerating). There is a fair amount of white smoke when I rev the engine while the bike is at a stand still.

Once I arrived home, I immediately removed the seat and noted that the air box lid had been removed by the previous owner and the filter was black. I removed the filter, rinsed it in some warm water, cleaned with simple green, and left it out to dry. I'll be oiling the filter and re-installing today. Do you guys think my symptoms are from a dirty air filter or something else (carb, jetting)?

Riding Info:

Elevation: Sealevel-1000ft
Mods: Air filter lid removed, twin air filter (stock expansion chamber and silencer)
Riding temperature: 10C-25C
Mix Ratio: 32:1 (AMSoil Interceptor)
Spark Plug: NGK BR8ES-SOLID

I would clean the carb. And take a look at the plug and see what it looks like. It may be loading up and taking a while to clean up. I would also take a look and see if your power valves are working.

royadams wrote:I would clean the carb. And take a look at the plug and see what it looks like. It may be loading up and taking a while to clean up. I would also take a look and see if your power valves are working.

I have no idea how to clean the carb or check my power valves but that's what the manual is for. :)

It should be noted that I'll be re-seating the expansion chamber, installing a new plug, and changing the trans oil in about a week or so. Once those are complete I'll attempt to check the carb/jetting and power valves.

Thanks for the help!


Any jetting recommendations?

I imagine your powervalve is gunked up. That is what was my bike would do before I did a top end and cleaned the powervalve.

2001kdx wrote:I imagine your powervalve is gunked up. That is what was my bike would do before I did a top end and cleaned the powervalve.

Can the power valve be accessed without remove anything else?

It's my understanding that the power valve is covered by a "cap" with 3 bolts above that sits above where the expansion chamber attaches to the cylinder. I haven't physically looked so I'm going by pictures in the manual (during a top end disassembly).

If you remove your pipe and look in the cylinder you can see the power valve. If you remove the side cover and move the shaft in and out both sides of the valve and the top valve should move.

royadams wrote:If you remove your pipe and look in the cylinder you can see the power valve. If you remove the side cover and move the shaft in and out both sides of the valve and the top valve should move.

Does side cover = KIPS cover? I'll try that this weekend. Thanks.

The cover to remove is the cover on the right side of the cylinder that the shaft goes up to that has three screws that hold it in. Then remove the LEFT HAND THREADED nut while SUPPORTING THE SHAFT. And then you will be able to move the kips by hand.

Or....

Remove the slotted cover over the KIPS main shaft on the LH side (flywheel side) of the cylinder. You can manually move the KIPS by way of the nut underneath that cover.

Taking the segment gear off the governor shaft will work fine. If you do it that way, you do run the risk of damaging the drive system of the KIPS if you don't know what you are doing. Failure to support the shaft as mentioned is only one way to muck it up.

In any case, you need to have the pipe off so you can look up INto the cylinder to determine that all three valves are moving as they should, specifically that are timed correctly.


White smoke comes from coolant leaking into the cylinder. Do you or have you been losing coolant?

Thanks guys, but I've actually noticed a huge increase in power since cleaning the air filter. It looked like the previous owner hadn't cleaned it since he bought the bike...in 2006.

After a short ride, I noticed that the front end wants to come off the ground when shifting into second gear while on the power band. Prior to cleaning the air filter, this seemed to only be the case from second to third gear.

I'll probably tackle the carb next week, after I replace the plug and refit the expansion chamber with new o-rings, springs, and a gasket. Hopefully that will make it even more lively.

Had same problem. Turned out to be a rich slow jet (pilot jet). Original was a 42 I think. I went down one size. Took 2.5 turns to max out idle on the original slow jet. With one size smaller it now takes a little over 1 turn. All is fine now.

as mentioned before: clean carb, then follow the jetting guide (check sig).
It's really straight forward to tear down and clean, don't dip the whole carb in solvent, there are a few tiny orings you could damage.
Once it's dialed in you'll have a much better enjoyable bike.

So I finally put some time aside to clean the carb today. I will say this, I was at first intimidated, but man, that tear down is a piece of cake!

I cleaned it and took note of the jets. The main is a 160 and pilot/slow is a 48. I did end up turning the air mixture screw out an extra turn (~2.5 turns out, total) and the bike is much more "peppy" with better WOT response, whereas before it felt like it was "bogging".

Should I re-jet to 155/42 or maybe move the needle clip one position toward the top (blunt end)?

Here are my riding conditions:

Elevation: Sealevel-1000ft
Mods: Air filter lid removed, twin air filter (stock expansion chamber and silencer)
Riding temperature: 10C-25C
Mix Ratio: 32:1 (AMSoil Interceptor)

2.5 turns out on the air mixture screw would normally indicate the need for a smaller pilot jet.

govols wrote:2.5 turns out on the air mixture screw would normally indicate the need for a smaller pilot jet.

With the air mixture screw at 2.5 turns out, the throttle response is much better when I crack the throttle. The bike is more snappy overall. If I went down on the pilot (and not the main), then I'd need to turn the air mixture screw back in for correct idle. This would reproduce the "bogging" feeling I get when cracking the throttle open, correct?

So, I'm wondering if I should go down on both jets or set the needle clip at position 2 (currently at 3), for the time being.

You turn the air mix screw to get the highest idle. If more than 2 turns go to a smaller pilot jet. And turn screw to find best idle again. I would only make one change at a time.

The jetting guide is the best way to go. It would indicate that your pilot is too small so I'd change that first. Then START AGAIN at the first step of the jetting guide. The bogging you're indicating is not Idle circuit but the main (but isn't really detailed enough bogging only at WOT, at rollon between 3/4 and WOT? etc). Adjusting the mixture screw is just masking the incorrect jetting. As Royadams said, one change at a time, then always start from the beginning.

Our carbs are pretty simple 0-1/8 throttle is Mixture screw/pilot
1/8-1/4 is slide cutaway/needle straight section/clip
1/4-1/2 is clip/needle taper/main
1/2-3/4 is needle taper/main
3/4 - WOT is main

helps when diagnosing to mark your throttle at the 1/8, 1/4, 1/2, 3/4 and WOT then note where the issues are, really makes pinpointing the culprit circuit easy.

Good info here http://www.carbparts.com/keihin/needles ... tuning.htm

Hi there.....
Sorry to jump in and hi-jack the thread if it seems that way, but I just wanted to ask a question with regards to one of the replies.

Canyncarvr noted:
"Remove the slotted cover over the KIPS main shaft on the LH side (flywheel side) of the cylinder. You can manually move the KIPS by way of the nut underneath that cover".
Can this be done without removal of the connecting rod/claw to check KIPS or will it damage the rod/claw???
I know to remove the cover with bike running and then rev to see if gears/shaft turn, just never read/heard of the method Canyncarvr noted.

Just curious and great if it works.......if it does, another thing learned.

Once again, sorry for the hi-jack, not intended.

Ditton

Can this be done without removal of the connecting rod/claw to check KIPS or will it damage the rod/claw???

Yes, won't hurt a thing using a nut driver.

Trying to revive this thread...

I have a similar problem. No top end power in 1st or 2nd but bike feels right in 3-6 gears. The KIPS is functioning (maybe a little sticky but working).

I went to adjust the air screw and found my highest idle to be alllll the way in. Idle decreases almost immediately after screwing out.
I haven't dug into the carb yet to see what jets i'm running, but this does sound like i'd need 2 size larger pilot jet? What about just moving the needle? This is my first 2 stroke and every 4 stroke i've had has been lucky enough to not need carb work.

TIA