I recently bought a California street legal 2003 WR450 set up as a supermoto. Pretty nice setup - Excel rims/Talon hubs, Brembo radial master, Braking 320mm rotor, Braking 4 piston caliper, FMF header, suspension redone for supermoto. The bike had been sitting for close to a year. I checked the valves and they're in spec. I cleaned out the carb, it was pretty dirty. It now runs pretty well when the lights are turned off, but when I turn the lights on I can't do anything more than putt around. If I stay at small throttle openings and low RPMs it runs fine, but if I open the throttle much it falls flat on it's face. I only did a few pulls with the lights off, but it seems to run well that way. The previous owner now admits that it was acting that way before (he didn't tell me before I bought it, oh well). I'm planning on putting a new battery in the bike - probably a Shorai - but I'd rather not kill it, which I suspect the current charging system will do. I have a good multimeter, so I can check what I should this weekend, but any suggestions on where to look first would be appreciated. Thanks for any help.