speedometer help please

[greengoon3]

I bought a 160 speedometer off of fleabay that was supposed to have come from an 79 XS1100. When I installed it on my 80 XS1100 special it is innaccurate. At 25mph it reads ~22mph. At 53mph it reads ~ 45mph and so on.
My question is is it possible the meter was on a bike with 18" wheel and mine is a 19" if this is the problem any easy way to rectify?

I also have a 120mph and when that was on it it appeared to be right. I think that the orignal 85mph was right also.
Thanks,
George

[jmnjrpa]

Don't know for sure if that is your problem but a larger TIRE size will equate to lower reading. IE- you will be going faster than the speedo says. This is true for the front tire only. Rim size does not count, only the total circumference on the tire. If you decide to get rid of the speedo, PM me.

[DGXSER]

If it came form an XS it should be 19" wheel IIRC. Fred is old enough to remember every year they were made.

I can tell you mine has the stock speedo and original AFAIK. I know for certain it is off by at least 5 MPH at about 60-80 MPH range. At least it reads that much lower than EGleaves speedo at the same rate of travel. Besides, on an XS11 the speedo should simply say "Just twist the dang thing!!"

[Ivan]

The problem with mechanical speedometers is they rely on spring tension against a spinning magnet. Over the years, the spring looses springiness. so you will be hard pressed to find a speedo that is accurate, unless it is an aftermarket new piece.

[XJOK2PLAY]

How are you making the comparison? Someone else riding beside you, or GPS?

As they've said, I agree... most XS/XJ speedos I've been around read about 5 fast of actual speed.