I am building a 350x and rebuilt the carb and was wondering if I should change the low speed jet? I have a complete Dg exhaust system and k&n filter. I bought a carb from ebay and it had and it was almost new but the low speed jet was bigger than factory. I am starting with a 145 main and 42 (instead of 38). What difference will it make? Better low end? I have no idea and help is appreciated? Thanks

 

Id leave it in, and try it out, Usually the mixture screw is adjusted right, when it runs well, and is about 1 1/2 to 3 turns out. If its less than 1 1/2 out, you need to go smaller....if its more than 3 turns out, go bigger.
Read more about it here.
carb

 

Hey Wesley,

Buster is right.

The 42 would be a great place to start anyway in carb mods.
I know that a bone stock 350X does well with a 40........so with the exhaust, the 42 might be just right, or just a bit much.