My yamaha yz 125 01 wont start no mather how much you push it or kick it. Fauling pulgs, Back firing, and Taking water...

does battery go flat, if so check rectifier is creating power and it wasn't just reliant on the power in the battery

Try putting a new sparkplug in could be fouled out. loud pop was just a back fire.

if the bike push starts, i assume it runs good,
if the kick does not turn motor over, there is a spring clip that engages the kick gear that may be broken or misplaced
if the kick start turns the motor over, you have to use decomp to get just past TDC then kick

hi,simple fix,simply screw the cap back onto the lead (right hand turn)until the cap is back on tight,there is a reverse screw inside the cap which threads its way into the lead as screw it back on,,hope this helps

sounds if you picked up some water/dirt in fuel when was low

clean fuel bowl and flush carb by drain port if still ruff then remove carb for cleaning

needle and seat are worn out in carb, to much fuel is flooding cylinder. remove carb, clean, get new needle and seat, set float. problem goes away. pull your plug after kicking. its probably wet.
When you push, or pull start you evacuate excessive fuel, when engine is warm, easier to start extra fuel burns easier.

check your compression I had a 94 yz that done that when i checked the compression it was really low so I put new rings on the piston and that's all it took to bring her back to life