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View Full Version : 400ex DMC Alien Jetting



FBRacing76
10-21-2004, 06:37 PM
Hey guys. It has been starting to get colder around here and my 400ex ran good all summer and I got on it today an rode it when I reved high when I was riding it spudered and backfired. I was running a 170 with open air box lip and DMC Full System, I just changed it to a 155. DMC's recomendations were 150-157. If any of you guys live in East/Central Us and run around the same set up let me know what your jetting is so I can get this figured out! Thanks!

cals400ex
10-23-2004, 12:34 AM
try keihin 158 mainjet
4th needle clip position in winter at least
42 pilot jet
2.75 turns out on the fuel screw