I have a 2001 400ex bored out to a 440 with stage 2 got cams. I decided to get it up and running again after a few years and first I was driving and lost power in throttle, bike shut off and gas came pouring out my overflow line so I figured it was the floats in my carb so I cleaned that out it back in and then I was driving home again and I lost power in my throttle backfired bad and the bike shut off. I figured it was low on gas which it was I put gas in it this morning and I tried to rev it and it just did nothing but make a pop but then I drove it around the yard and it was fine again I’m just confused at this point.

 

If you run a bike low on fuel you are more likely to get dirt and/or water through into carb, which is probably what happened. If it runs OK now, this has cleared and may not cause any more problems. Or more dirt/water could get through and give trouble again.