I am still having a problem with alot of popping when I let off the throttle.
I have an '04 DS650 Baja with a TRX450R carb, an end cap, and a procom cdi.
I changed the pilot jet twice now a put a 55 in it now from a 50. It still pops like crazy as soon as I let off the throttle unless I pull the clutch in. It is also very hard starting when it is cold, it wants alot of choke for a long time.
Does it still need to be richer on the pilot jet or could there be another problem?
Thanks

 

have you adjusted your air fuel mixture? for your idle jet. I do beleive you are lean { to much air } easy way to find out is block off some of your intake air to the carb if it starts easy you need more fuel http://www.sudco.com/mikuni.html this may help

 

I agree, idle mix is lean, this explains the popping and the hard starts both
you need to richen the idle mix screw

I am not familiar with this particular carb - some idle mix screws control air, some control fuel, rule of thumb is if the screw is located on the bottom of the carb between bowl and engine then it controls fuel and needs turned out counterclockwise to richen

 

I would look for an exhaust leak where air can be drawn in giving your unburnt exhaust gasses that build up during decelleration enough oxygen to igninte. reseal everything and see if its still does it.

 

Ok I will check those things and see if it helps.
Thanks everyone for your help.

 

If idle mixture screw is closest to intake manifold it is will adjust fuel, if it is closest to your air filter it will adjust air.