Has anybody tried this dial-a-jet thing. It looks like it would work pretty good, but I just don't know if it would hold up to the punishment of being submerged in mud. What do ya'll think or know?

 

I tried one and couldn't tell a difference so I took it off.

 

it can really help on a stocker low quality running carbed bikes,
especially when you go through a lot of elevation or temp changes,,
on high performance carb like the pwk 39,it doesn't worth $hit and it is
actually worse than a fine tuned one,,i found the dial-a-jet do work better on low quality mikuni carb to improve fuel atomization,a thing the keihin are superior for from my past testing.