I got the jetting right!

[Red Rooster]

But The motor backfires when I just ease of the gass when I'm moving. And if I blip the throttle in neutral, it also backfires when I let off. I think I have to adjust the air-fuel mixture screw. I don't have a 400ex manual so I don't know what screw it is. Please tell me which screw it is and if you think this will fix it. Thanks, Nate

its the screw on the very bottom of the carb. i jetted my 400 and the screw is 3 turns out. so turn it till its seated and take it out 3 turns and try it. if that dont work, keep goin out in 1/2 turn increments.

[Blake24]

try bumping up the pilot?

[Red Rooster]

well the carb is a 400ex carb on a 300ex. and I will try turning in in and then turning it out 3. It has a 45 pilot and it runs good. except for the backfire. Thanks for the help. 1 more q, how many vent hoses are on a 400ex carb? There was just 1 on and I put another on where I thought it had to go on the left middle.

[Razorback]

it could be a slight exhaust leak, which can cause that noise. for example, where your silencer connects to the pipe might be leaking slightly. you can search through some old posts to find out some more info about this...

[Red Rooster]

Just wanted to see if you people thought that adjusting this screw would fix it. thanks to all who have helped out already.

Razorbackexrider, the exhaust is not leaking anywhere.

[Razorback]

ok, it was just a thought. hope everything works out ok.

[Red Rooster]

Yep, Thanks for the suggestion. I never knew that would make that sound if the exhaust was leaking.