As an add-on to the comment regarding the heavy/light spot on the tyre, whilst you have the bike with its front wheel off the deck, make sure that the brake pads have released enough so the wheel spins freely, then just give the wheel a gentle spin and make a mark on the lowest part of the tyre where it stops. Repeat this a few times, if it stops at the same spot, that's your heavy area. Many moons ago I unknowingly lost a balance weight from my front wheel, and at about 35-40MPH with a closed throttle, a firm grip was needed on the bars to stop it developing into a "Tank Slapper". Stay upright, regards, Mick.