I recently installed a K&N air filter to my 2012 ninja 250 since installing a more breathable filter should I shim my carbs? Will it increase my throttle response? And should I remove snorkle completely or trim down the snorkle a few inches?
.... Shim the needles with (2) two 3mm washers and remove the snorkel. Shims add a little bit more fuel to the 1/4-3/4 throttle range, a little more fuel results in better throttle response-(simple, don't complicate it)(If you have a slip on exhaust removal of the kleen air system is optional if you don't mind the popping.)
Shortening the snorkel does very little. Either leave it in without the shims or completely remove it when you add the shims.