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I have cleaned carb, rejetted it. Checked valve clearance. checked the Throttle sensor. But bike battles to idle, idles very high on choke and surges off choke. I have to keep on adjusting throttle position knob on carb. if cold it idles high and as it warms up i have to turn knob to drop idle rpm's. I have unplugged throttle sensor plug and nothing changes.Throttle sensor checked with throttle position screw fully out, so that it doesn't influence throttle sensor.

I am out of ideas.

It sounds like it could be the Needle Jet , its the copper tube that the Needle goes down thru and the Main Jet attaches to , when it becomes worn , the needle will bounce around causing erratic idle , i would also check the Needle itself for wear , if the Needle Jet is bad enough to cause the idle to go up and down , then the Needle itself is most likely worn , you can tell if the Needle is worn by discoloration on the shaft , the Needle Jet you can't physically look at and tell if anything is wrong

The Backfiring could be because of the worn Needle and Needle Jet , and messing with the mixture screw to try to cure the issue

This is what a worn needle looks like , note how its discolored near the fingertips , that is worn thru the coating , so it needs replaced