Jetting Issue!

[roamer9562]

Just moved to the east coast from Utah and re-jetted my 2005 400ex and the local honda shop suggested a 40 pilot and 155 main for the setup i have..Bike runs great with this combination great hook up and top end with no misses at all..The only problem is when i shut the bike off, about 5 to 10 seconds pass and i get a big WHOOF out of the pipe...Is this because of the fuel mixture being too rich? Just wondering if someone could shed some light on this for me...don't want to damage anything. Thanx. Roamer

[Colby@C&DRacing]

have us adjusted your valves lately and what is your altitude?

[roamer9562]

Altitude is around 600 to 700ft...and valves have not been adjusted...The bike only has around 50 hours riding time on it all together since i bought it new. Only time i get the noise is when i shut the bike down not when it is running..Just wondering what it could be.