I have a new to me 2006 KLX250. The stock carb has an adjustable idle mixture screw and an adjustable needle so must have a jet kit. The needle is also unmarked. The ID of the main jet is 0.050". Does anyone know what would be the equivalent Keihin jet size?

It came with no snorkel but I installed one of the KDX200 ones. Response is very soft at all RPMs but it sounds like that is to be expected. A while back I had a KLX300 that had a nice strong push right off of idle and not much else. This is similar but missing the push off the bottom. Is that normal?

 

The quick snap from your KLX300 might have been due to the gearing...usually much lower than the KLX250...unless yours is modified. That's fairly strange that the main jet has no markings.

 

Usually size is stamped on the side and sometimes little difficult to read magnifying glass helps.