I bought a bashed-up DR350 and rather than take the time to source a used tach I installed an Acewell 3700 series on it (http://www.electrosport.com/street/s...eries-3700.php
I found the wiring instructions to be a bit vague but not unmanageable- but there wasn't any real help when it came to mounting the pickup or magnet. The supplied magnets were both useless for this application and I ended up using a magnet from a fridge hold down that I epoxied into a depression I drilled into the rotor. I had to fab up my own bracket for the pick-up, and the length of the supplied cable (not easily modified) meant it had to go in front of the fork leg in order to accommodate the long travel suspension. The installation turned out to be a minor PITA but I am very happy with the instrument and it's function- enough so that I'll probably buy another one to replace the Vapor instrument on my XR650R
My Bracket solution:
The addition to the standard brake mount was made from a scrap of 1/8" steel plate. The center was cut out to make it lighter
Mounted up. The plate is curved to hug the fork leg and provide clearance for the rotor.
All done. The magnet depression was started with a standard bit, then flattened with a reground bit of the same size so that the magnet would seat firmly. A little metal epoxy was added to seal the deal.