Ok guys just bought me a 2006 400ex it has fmf power bomb head pipe hmf exhaust.It was smoking and plug was dark brown.Called hmf to see what jets to start with they said 42 p 152 main and 2nd from bottom on neddle.Took carb apart it had 185 m dont know what brand every thing else was stock put the new jets in the neddle isnt adjustable played with fuel air screw ran bad.I put it back to 38 p 185 m dont know what brand but hole is bigger than 152 keihn played with fuel air screw run pretty good.There is two problems when just kinda puting along and hammer it it just cuts out anf want to die 2nd prob is decel pop.Any ideas oh ya i put k&n on and took lid off.Thanks

 

One other thing I forgot about after running down the road at wide open when I slow down to turn around it wont stay running I have to keep it running for 30 seconds and then it runs fine again

 

Can anyone please help.

 

i have a 07 155 main dynojet 42 pilot. needle is dynojet set on middle slot. hmf slip on just to compare.mine might still be a little rich.565ft above sea level