fmf 4.1 muffler w/ megabomb jetting questions?

I have a 09 YZ450F and I just ordered the megabomb header w/ 4.1 muffler. I went to FMF website and looked at the jetting section and they had no jetting chart for my bike. Dose this mean that the stock jetting is correct?

check out the sticky on jetting. I have an 09 with the 4.1 and megabomb at 700ft. I went to 165 main, 4th clip on the needle, and fuel screw 2 1/4 out and it runs like a champ

I have same bike and system except the 4.1, I have a power core 4 with mega bomb and twin air filter. I didnt get time do jet the bike or run it. Im gonna try what you did. 165 main 4th clip position and 2 3/4 out on fuel screw. Wish me luck.

165 main, 48 pilot and 06 needle in the stock position. Fuel screw right around 2 turns. I am running a Megabomb header with the stock muffler completely opened up w/ PMB end cap. Runs great and starts better than my buddy's EFI RMZ450!

Got my new exhaust and installed it. Thank you! I did what you said to the "T" and it runs great. I'm at 1000ft were I ride so I tweaked the mix screw a little bit different but did the 165/48 jets and needle adjustment.:thumbsup:

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