What would make a scrambler 500 pop and backfire when you let off the gas? He already adjusted the ETC and idle and it didn't help. The quad is stock. Any help would be appreciated.

 

Well if ya already checked the ETC and took the slack out of it my next course of action would be you are to rich on your main jet try dropping a size I know my did this when I rejetted for winter and now that the weather is warming up I had to drop a size because mine was backfiring after a full throttle run.
Hope this helps

 

Your mixture is a little lean on the bottom . What you need to do is turm the mixture screw on the carburetor outward .

The mixture screw is on the underside of the carb in front , under a pressed in plug.

 

Do what Rick said he is more knowledgable than me

 

will turning the mixture screw out make it more "lean" or rich?

 

i have a k/n filter and a aftermarket silencer on my 500 and it is doing the same thing. any ideas?

 

Turning outward richens the mixture . Your K&N'd bike could use that adjustment too ..

 

Sorry to bring back a dead topic, but I searched everywhere about this same problem, I have a 2000 scrambler 500 4x4, dont know much about the bike, it has a k&n airfilter on it. Starts up just fine even with pull start only takes 1 or 2 pulls, runs like a raped ape on low end wheelies real good, but when Im gettin on it real hard on the top end it pops when I let off the gas. Now I have already adjusted the ETC, the choke, and backed out the screw on the carb( only about an 1/8th of a turn didnt know how far to go). Still have no luck. Im gonna bypass the reverse override to see if it helps any. Does anybody else have any suggestions that might help??....Thanks in advance

 

did you guys look at the spark plug to see if its running rich. it should be on the dark side i would think if its running rich.

 

RICK and your spark plug tells all that is good [img]i/expressions/face-icon-small-smile.gif[/img]