Rancher2005
06-05-2006, 04:30 PM
my 03 400ex is completely stock except for the uni filter i just bought.. airbox lid is on..about 200 ft. elevation .. when i installed the filter it stumbled just above idle...it started to make a small popping noise(exhaust) as i tried to open it up, and one of the headpipes started to heat up at the flange. it was much smoother with the choke at about 1/2 so for all of those reasons i am thinking it is lean. i am going to buy larger jets to richen it up and extra spark plugs to test with tommorow. I didn't think that just a filter with airbox lid on would cause such a dramatic change in air/fuel ratio. Anyway, what jet size would you recommend starting with . A DJ 148 is stock, correct? Thanks