Piddling carb (not what you think)


Oct 14, 1999
Something that comes around time and again is the question, 'My KDX piddles gas when it's on the side stand.'

Yeah. Generally considered 'normal' if you're on any sort of slant at all, and your float level is spec (16mm drop I think).

Here's a bit of a wrinkle.

My bike started the piddling routine this past weekend. No particular reason for it to...I've dropped the float level a couple mm, so I've not had any incontinence problem. I did have the carb out several times playing 'fun with jetting'.

What was new was the boyesen rad valve. It does NOT have a 'key' for the front end of the carb like the OEM boot does. You can put the carb in at a bit of a slant, which will make it piddle much easier.

With the rad valve, the carb sits a bit further to the rear, so clearance is a bit less. Although the whole thing is crooked and slanted to start with, tightening the carb with it in pretty much the furthest CW (viewed from the rear) position will be close.


Aug 7, 1999
Another thing to check is the needle valve which regulates the flow of fuel into the carby. If the seat is worn, or if it has a tiny bit of grit in it from dirty fuel, it won't shut off properly and then the float bowl will keep on filling right out of the overflow pipe.
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