Apr 23, 2001
I recently purchased some additional jets for my 2001 KDX 200 and I'm attempting to lean my bike down from it's rich condition. I've read the jetting recommendations from CD's website, but still have a general question. Is there a relationship numerically with the main and pilot jets. In other words can you run a 38 pilot with a 155 main or is there a rule of thumb regarding separation of the two jets sizes?


May 17, 2000
No relationship

All the carb circuits work together to some extent but going way too lean on the pilot will cause BOG but will not effect the plug color of a WOT plug chop.

Jet the Main for a nice plug color usually a 155 or 152, then jet the rest of the carb for best throttle response, usually a 45 or 42 pilot. Besides temp and elev jetting also depends alot on what mods you have done to your bike.

Most of us with late model 200's should not need to go leaner than a 152/42 combo.


Oct 14, 1999
Mac's right on.

Keep in mind that the pilot circuit needs to be adjusted using throttle response as a guide...NOT hi idle. Hi idle is a STARTING point, but fine tuning comes from quick-wicking the throttle.

Changes to the air screw as little as 1/16 of a turn make a difference on my bike. Also...hard starting when hot can be resolved by slightly richening (air screw in) the pilot. Slightly meaning 1/16>1/8 turn in.

The relationship tween the pilot/main numbering system is: They are both base 10 numbers..that's about it. ;)

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