Jet and needle questions on an 38mm Tri Z carb

[TRI Z Racer]

I have a Mikuni 38mm Carb, i read the yamaha report thingy and was wondering whether it would actually make that big of a difference over my stock carb. I had the carb laying around from one of my snowmobiles. Does anyone know what jets and needle i should use. My machine is .040 wiesco over with a K+N and DG pipe and silencer. If anyone could help id appreciate it greatly

[mike from long island]

i have been trying to figure out if its worth it too. i had a few carbs kicking around and some worked like crap. not sure what size they were though. so i have been just using a stock one. i have a aftermarket pipe 80 over,boyseen reeds,and thats about it. i have a motor that i want to use(tri-z motor still) thats been ported and polished and had lots done to it. i am going to have to find a carb that will work. i have been told that rad valves from a dirtbike will fit so i can try to use other carbs but thats done the road good luck

[YTZ250N]

I have a TM38 on my tri z with a pipe and no air box If I remember right I have a 450 main with a 55 pilot I have no idea what needle and nozzle I am running. if I remeber right the air screw became super sensitive and I had trouble cleaning up the very botom end. It still seems to be running kinda rich but not too bad and I think it is good enough for the riding I do. Just do little steps one circut at a time and watch your plug.