Motorcycle Repair: 42 MPH, fed 2002, time plug

Question
Got an electrical problem thats giving me fits! Have a Carb fed 2002 classic with an odd electrical issue. The speedo is stuck at 42 MPH all the time, No matter if the bike is turned off or traveling down the freeway. No horn, signals, brake light & the speedo light does not come on. Everything else is fine.. The accessory fuse blows the instant you turn the ignition on. Ive had this thing stripped down looking for what I hoped to be obvious. Like A chaffed or broken wire? Is there a sensor or something that may cause this?

Answer
What you need to do is unplug all the parts that are affected so there is no power to them. replace the fuse and one at a time plug them back in and see what blows the fuse, then you can trace down the problem. It sounds like a wire touching metal somewhere
good luck and happy riding
Mike