[tcoon]

I HAVE A 2008 CRF450 DIRTBIKE, I RECENTLY BOUGHT A FMF MEGA BOMB HEADER AND AN FMF POWERCORE SILENCER, I LIVE IN NORTHWEST PA, WHAT SHOULD I DO ABOUT RE-JETTING MY MACHINE?

[motosicko]

I just recently got RE-SCHOOLED on the jetting on my 08. For 2 years I've been running 172 main and 45 pilot, and thought by the nice tan color of the plug and how well it ran that I was spot on. Well after a trip to Sisneros Speed Works, and his dyno with wideband sniffer, found out I was way rich. Ended up with a 158 main and 45 pilot, and gained 2 HP. I have tried running a 168 in the past, but my plug got charred white color and it scared me into richening it up more. Eddie told me that trying to jet by plug color would have me chasing my tail and that todays cleaner fuels don't color plugs like they used to. Anyway to answer your question by my new jetting standards, these are good starting points, doesn't matter what pipe. Sea level 165 main, 2000 feet 162,
4000 feet 160, 6000 feet 158.