Little help with an FCR carb

[bloodmoney23]

Hey guys, my brother just bought a pretty nice 05 YFZ 450 all done up and stuff. The thing is it needs jetted really bad. And i woulda been able to do this w/o asking but I never messed with an FCR or a YFZ. I know most of you guys know your FCR's so can yall give me a roundabout starting point. The bike has an ESR alluminum Intake w/ uni filter and full Alba Exhaust. This is what it had in it and it ran like hell and shot flames about 2 feet and popped quite a bit and i know its pretty lean.

Needle: Stock
Main: 170
Slow: 42
Leak: 90
A/F Screw: Stock and havent checked how many turns its out yet.

If yall can school me up on FCR's a little and put me in a good ballpark area of where i should be closer too let me know and i would much appreciate it.

[TRX450RACER174]

If you do a search in the Yfz section you should find all your answers, to me that jetting sounds about whats in our Yfz but we have the YZ450 needle i believe it is a NCV-Q needle and a adj a/f needle, with a LRD exhaust ,no air box lid and a 13.1 piston with the cam mod, but search the YFZ section and you will get all the answers you need thats what i did.

[d3ktrix]

When is it popping? While ur on the gas or when u let off?

170MJ for an 05 YFZ sounds about right for summer weather. If it was cold out the day u saw it run, it's prolly kinda lean.

170-172-175MJ is the most common for that bike in the summer.

42 pilot is lean no matter how u look at it, at least a 45, 48 maybe.

And yeah the NCV-Q is recommended, helps alot. Start on the 4th clip.
Though the 04-05 YFZ have adjustable needles I think, the 06 needle isn't adjustable.