Well I took the tach apart this morning since it was just plain crappy out and I found that the thing wasn't working due to spider webs. Yes, spider webs...
Apparantly I should have thought more about it when one day while I was on the bike, a spider had crawled into the tach face and was dodging the needle as it swept past. When I opened it up and placed voltage to the red and black wires, the needle moved only to about 2000 rpms. I decided to manually sweep the needle and it broke the egg sac enough so that the spring could allow the needle full range.
After cleaning out the remains of spidey, the tach swung out to 7500-8k with 1.5v as indicated by interfuse and all was well. Reassembled and reinstalled and tested: bingo, the tach works once again.
Some helpful hints to people who want to take the tach apart:
-All you need are a 4mm, flathead screwdriver (more on that later), and a phillips screwdriver.
-An easier way to get the the back of the cluster to get to the tach is to remove the headlight via the four 4mm bolts holding the bracket to the fork tubes. This allows the entire headlight assembly to tilt down far enough to get to the three 4mm screws securing the tach assembly to the rest of the cluster. Enough access even with a flyscreen attached.
-You have to pry the chrome bezel off of the white plastic barrel around its perimeter. This will more than likely distort the bezel enough to be noticeable since it is so thin and stamped shut. Take your time and you will minimize the destruction. Do not pry too hard as you will split the housing and be really SOL.
-Make sure you clean your prints off of the guage face and the inside of the glass before you put it back together. Yes they will show up and it will piss you off. This isn't a job that you really want to do twice for a stupid reason.
-Before reassembly, you can smooth the "dents" in the bezel by crimping with a small set of pliers. This will minimize the distortion to the metal as it is easily seen where the bezel meets the chrome outer surround of the tach. You can "reseal" the bezel around the barrel by tapping the metal down with a plastic mallet gently. This will at least recreate the peening over that the factory does to secure the bezel back onto the plastic barrel. Make sure you support the face on a couple of rags before so that you don't flatten the curves or break the glass.
That's it! Hope it helps a couple of folks out. I decided to do this as my tach wasn't working and may have needed replacement anyway. Total time: about an hour.
-Randy
Topic: Tach question (Read 3817 times)