Speedo question

[tkent02]

or you could just put your own markings on the speedometer, like these:

http://www.thegsresources.com/_forum/showthread.php?t=130920&page=25&highlight=face+plates

[blackhawk]

I finally got around to try the calibration on my speedometer (81 GS1100E). I have not tried the bike out yet on the road, so I don't want to jinx myself, but I think that I have it calibrated. The spring in mine is a spiral one. The one end is attached to a brass collar that sits on the shaft. The second end is attached to a little sheet metal leg that is riveted to the speedometer body. This second end is sitting horizontal in the speedometer. The little sheet metal leg can be pushed in or out with a small screwdriver to easily adjust the tension on the spring. You only have to move that leg less than 1/64th of an inch to change the speedo reading. To ease Chuck's concerns, I don't see how you could break the spring unless you tried to move it some huge amount, like 1/2 an inch. If you move it too far, you jest bend the leg back the other way just a minor amount. I adjusted it 5 or 6 times to get it right.

Here is how I checked the calibration, since I knew that my odometer was measuring correctly. I borrowed a drill that turned pretty fast (2400 rpm) and used this to turn the speedo. I then ran the drill slowly to get the 1/10th mile part of the odometer to read where the top of the 0 was exactly lined up with the opening. I then ran the drill wide open for exactly 2 minutes. (I used 2 minutes instead of 1 minute, just to lessen the error.) After 2 minutes the odometer read just under 2.2 miles. So, 2.2 miles / 2 minutes = 1.1 miles per minute. So 1.1 miles per minute * 60 minutes per hour = 66 mph. My speedo should be reading 66 mph. My speedo was showing about 78 mph, so it was way off. I then kept adjusting that spring leg until I dialed it in to read 66 mph.

I actually had two other speedometers from 81 GS1100 bikes that a friend gave to me. (He used to buy junk bikes.) I tried the drill in these as a double check, just assuming they were correct. One read 66mph and the other read 65mph. With this double check, I felt pretty good. The road test will be the true one.

I took a picture of the inside of my speedo showing the spring that gets adjusted. I will try and post it soon.

[posplayr]

I actually had two other speedometers from 81 GS1100 bikes that a friend gave to me. (He used to buy junk bikes.) I tried the drill in these as a double check, just assuming they were correct. One read 66mph and the other read 65mph. With this double check, I felt pretty good. The road test will be the true one.

I took a picture of the inside of my speedo showing the spring that gets adjusted. I will try and post it soon.

Clever ; I use my drill to test spedos and tachs but never calibrate