Started backfiring, not running idle, lost of power?????

[mifun3]

Buddy just bought a 02 wr426, after a 2 hour ride the other night bike started backfiring no idle .....

Changed the spark plug and gapped.

Checked cap vent-good

Read maybe carb dirty tps cdi????? Flywheel key sheared??

Any suggestions?

Tks

[brad the best]

unplug tps .

clean the carb .

make sure intake boot seated right . no air leaks .

clean the air filter .

buy new gas .

what color was the spark plug ?

check flywheel key .

check connections .

replace cdi

thats the order i would go with

and since he just bought it i would check the valves , not that its your problem but it is a good idea .