I was changing the front tire on my 98 WR400 that I just got and found a sensor that was attached to the two bolts that clamp the fork onto the axle. It looks like a magnetic sensor that trips every time a bolt on the wheel passes it. The wire runs up the left fork and has been cut about halfway up. It is black taped to the brake line. It is not the cable for the tripometer and I can't figure out what this is for. It doesn't seem to affect anything on the bike that I can tell. Was this a speedometer cable?