Mr. Blubber PJ Carb Be-Gone

[White_Knuckles]

Solution to those following my mystery PJ carb swap discovered on a used 2000 KDX 200 putchase. That bugger made a rough low range followed by MX type hit at mid to top end. Keihin claims the PJ series are "low end" carbs where the factory PWK style are motocross favored "top end".

Thinking it's worth an attempt to correct I dropped the PJ pilot down to a 50 (they run fat), lowered the needle a click and left the 155 main. I found little improvment and still drifting idle. Checking with RB designs, Ron suggested to get rid of the PJ rather than tweaking it to death. I ordered a new 35mm PWK from Sudco jetted 42,155 with a #5 slide. The tech was great and agreed the PJ was evil. He looked up the numbers and found the PJ was a 34mm with jetting close to what an RM250 would run.

I mounted up the new puppy and the bike is a delight. Very even throttle response, no off idle blubber and idles consistantly. The hard hit is gone. Strange how a carb can change the machine that drastically.

 

[JasonWho]

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[jaguar]

If the hit is gone then the jetting is off.
Hey, did the SR carb boots (fore and aft of carb) work with the bigger carb? Or did you go to using the boots off the 2000 KDX200?

 

[White_Knuckles]

Jag, well the "hit" is still there but you can sneek up on it rather than blub, blub...WAAAAAA as it was before.

The stock 2000 KDX 200 boots work with both carbs as the 34mm PJ has nearly the same outside dimensions as the 35mm PWK. This is the stock size (35mm). The 34 PJ was a strange adaptation by a prior owner for an unknown purpose.