Hi, Pist'nbroke put an excellent guide to replacing your speedo sensor with a commercial proximity sensor:[URL="http://apriliarsv.com/guides/16285-inexpensive-speedo-sensor-fix.html] Inexpensive speedo sensor fix. The only tricky bit is getting the new sensor mounted. I drilled the old one out and bolted the new one in the old housing. It took about 1/2 hour. The sensor in the guide wasn't about when I did mine but you need a PR12-2DN (Normally Open) 2mm detect distance, 800 Hz. i tried using an 18mm one with a 10mm detecting distance but it only worked up to 40mph. I then bought the 12mm unit Best £5.36 I ever spent!!!
Oh, See that they're £4.20 now. See ebay item No. 190837017850.
Phil