Put the axle through the wheel, put it on a pair of jackstands, and spin it slowly until it rests on the heaviest part. Stick the weights on the opposite side and repeat. Yes, the wheel bearings have drag, but you can estimate the heavy part by nudging the wheel, then observing the rate at which it slows down. Maybe not good for 100+ mph, but it worked for my DRZ and my former XR650L. Some people never balance dirt bike wheels
so this approximation is far better than most.
"We hang around people who think these activities are normal."
"Me and gravity, we are really, really good friends." - Streetbike Tommy, Nitro Circus
"I'm a dude in his mid-40s, who acts likes he's in his 20's. But I don't plan on stopping any time soon." - Ken Block