Does a DMC full exhaust kit for a Z 250 require rejetting?

 

Jets are basically brass bolts that are drilled to allow gas to pass through them. With an aftermarket exhaust, i would say a jet change would be mandatory. Your main jet and pilot jet are located in the float bowl of your carburator. The float bowl is on the bottom side of the carburator, and the gas gets into your motor by going through the passage in the jet. The size of this passage is what determines how much gas is allowed into your motor, determining your leanness and richness. Since more are will be allowed to enter and exit the engine because of the aftermarket exhaust, more gas will be needed to keep the motor in its current running state. Four screws take the float bowl off, and i think its either a 5mm or 6mm socket that will take your main jet out. For the new jet you will want to go to a larger size (bigger number) so talk to your local dealer and see what they recomend for a new jet size. I would recommend going up one or 2 sizes, so if you're at 320, then goto a 330 or 340, but definately ask your dealer what they would recommend. As far as changing the needle (the jet that adjust the amount of fuel flow up till 1/2 throttle), I dont think you'll need to change it with just a pipe. Thats all of my .02 that i can give you, hope it helps.