2003 kdx200 on a 2004 kx250 frame

mliz · Post by **mliz** » 07:50 am Oct 18 2016

Hi,

I recently traded my klx250 for this flawless kx-dx hybrid minus the chamber which was dented and punctured in multiple places due to someone not knowing what they were doing trying to make it fit. Everything checks out but I am still unable to get it running right.

Here is what I am running:

FMF Gnarly Pipe (New rubber and copper gasket and springs)
FMF PowerCore 2 Silencer (Brand new packing)
35mm Keihin PWK (stock for kdx200 h models)
Stock KX250 Airbox (Clean and oiled filter)

I have eliminated every problem so now it has to be the carb. I have rebuilt the carb with new pilot and main jets, float bowl gasket, idle screw, mixture screw, jet block gasket, new needle, and cleaned it thoroughly with carb cleaner and a guitar string. Also, took everything back apart after first unsuccessful try to get it running to make sure everything was as/where it should be.

I rejetted to what FMF suggested (155/48) and no luck. Ran the idle screw all the way in and still no luck. Dropped the pilot down to a 35 and still too rich. The only way I can get it to idle is by using the throttle adjuster to bring the slide up high enough to let it breathe which I know is NOT the way you want to set your idle. Also, every time I pull my carb it is wet with gas on the intake side. I am thinking something is worn out internally (whatever the PO soaked it in was some nasty stuff, jet block o-ring was almost completely not there) but before I drop $200+ on a new carb I was wondering if anyone has had similar problems? Or have any ideas what is going on because I am out of ideas.

Thanks,
-Matt

royadams · Post by **royadams** » 08:47 am Oct 18 2016

Low speed screw all the way in is richer. How is compression, reeds, crank seals. The jet block gasket can also be tricky to get seated.

mliz · Post by **mliz** » 12:54 pm Oct 18 2016

Mixture screw is 1.5 turns out and it does not matter where it is set at, since I have to bring the slide so high to get it to idle.
Reeds are flawless.
Countershaft seal was replaced but not sure about crankshaft seal. It is not drawing oil up and oil level in trans is constant so I think those are good.
Have not checked compression but looked in cylinder and it looks perfect.
Jet block gasket is seated correctly, made sure of that when I took the carb fully apart 3 times.

Tedh98 · Post by **Tedh98** » 03:47 pm Oct 18 2016

How did the PO get the carb to mate up with the 250 airboot?

mliz · Post by **mliz** » 07:10 pm Oct 18 2016

It fits perfect so really not sure if he did anything special.

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G22inSC · Post by **G22inSC** » 07:26 pm Oct 18 2016

Maybe due to minor differences between a 125 and 250 frame? Just guessing.

mliz · Post by **mliz** » 07:28 am Oct 19 2016

G22inSC wrote:Maybe due to minor differences between a 125 and 250 frame? Just guessing.

Pretty sure it is due to a shorter airboot from the air box to the carb. At least that is what I read in another thread.

JL4049 · Post by **JL4049** » 06:01 am Oct 24 2016

If it's soaked with fuel on the intake side, and it's not float level related, chances are your reed valves are stuffed although you checked these. How well are the reeds centred on the plate? If they are off to the side a bit, the edge can catch in the housing and hold open a bit.

mliz · Post by **mliz** » 03:25 pm Jan 07 2017

So it has been a while since I posted but some bottom end work was done. Engine got new crank bearings, a new governor lever (what opens the kips), cylinder got a light hone with new rings, clutch basket got a smoothing out, and everything I could possibly check, got inspected per the manual

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mliz · Post by **mliz** » 03:27 pm Jan 07 2017

Everything was in spec and looked great. Valves look good but now I am thinking it must be the float. The carb seals when at the exact right spot with I take the bowl off and blow through the inlet tube. The carb has been fully rebuilt but still no luck. The carb is very rough and looks like it has been soaked in some crazy strong solution since some of the metal is pretty worn. Sourced a new carb and should be here soon. I will post again when I get the new carb. Hopefully it fixes all my problems.

Post by **KDXGarage** » 01:56 am Jan 08 2017

Goofs luck with it.

Kxrob · Post by **Kxrob** » 05:27 am Mar 03 2017

Might be a bit late , but is the carb sealing around seal of air metering block

mliz · Post by **mliz** » 11:30 am Mar 03 2017

New carb is on and it is running nicely. Need to still perfect the jetting but since it still pretty cold here, I am going to wait until we have a 60+ degree day.

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mliz · Post by **mliz** » 11:33 am Mar 03 2017

The carb was all sealed up. Had it running and sprayed some carb clean on the rubber boots and where reed boot connects to the motor. No rise in RPMs so I am thinking I have a good seal.

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