taillight works when not running????

[Quad Dude]

ok guys here the deal my buddies got an 05 450r and were haveing some issues with it running right. and we thought we had it dialed down to a jetting problem. but while we were working on it we had just shut it of to and i grabbed the brake lever and the light flashes on and then fades out you can do it a few times before i dont come on at all. do others do this or do we have an issue. we swaped out stators and all the other electrical like cdi box voltage regulator and both the every thing else under the hood. no change. im baffled. and for any one that doesnt know 05 450r's were kickstart. no battery. any idea would be helpfull thx in advance josh

[miles Machine]

I wouldn't think it would do that unless the key was on while you were doing it.
the kick start models have a dc cdi meaning they need a dc power source like a battery, but instead to keep weight down and because they don't need a battery the use a capacitor that stores a small charges of rectified electricity. If you have the key on and its blinks its more than likely just using the remainder of the juice left in the capacitor