popping noise after deceleration after removing air pump

new wr owner, just removed air pump , used the yamaha kit, done the full mod, exhaust tip,airbox restricter, grey wire. now it pops and burbles under decelaration, followed directions, used 48 pilot,supplied needle, no other jets, air screw 2 turns out. runs good , but annoying pop , also tried 06 yz muffler and it made the super loud pop and foot long blue flames, am i too lean on main jet??? took yz muffler off as it was machine gun popping bad!! an new to 4 stokes after retiring the 90 cr500. please help!! dealer is a moron.only thing i didnt do is cut the airbox.

did not mention that i am in indiana , so altitude is not a problem

Decel pop is a lean condition

Get the JD jetting kit from the TT store and put the red needle in clip #5 or blue needle in clip #3 and 170 main. :thumbsup:

Believe it or not the needle position and taper is critical for good jetting! Get rid of that fixed needle immediately! :bonk:

It's gotta be the Main Jet. I agree with the 170 Main, your needle is not adjustable but that doesn't matter cuz it's fine right where it is. If that doesn't work take it over to Indys house...... :thumbsup:

He Has Removed The Fixed Needle And Replaced With Adjustable Needle.

problem solved!!!!!!! 170 main jet and msr easy adjustable air screw 2 3/4 turns out!!!

do you need to remove the carb to do the jeting?

You can get to the main with the carb in the bike. But the rest of them you need to remove it. I guess you may be able to replace the pilot, but it would be difficult with it in the bike.

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