Hello everyone, I was just thinking: while I've got my rear wheel off (1965 B40F), should I be having a look at my speedo? It tells lies, in that it says I'm going faster than I am. So if I'm really doing, say, about 40mph, it tells me, say, about 60mph (these figures not at all accurate, just to illustrate that it is a long way off, not just a couple of mph out.)
So do you think I should be trying to sort it? Or is it a specialist job? I know nothing about speedo's, by the way, but would be very pleased to learn, if it's pretty simple and needs no expertise or special tools/equipment. If you think I should be doing something to fix it, er...could you tell me how to do it please?
Thanks again, as ever, Phil.
Actually, sorry, just realised I asked this back in November. Of course if there are any thoughts from anyone who wasn't involved in the discussion back then, they'd be much appreciated. Phil.
You may have the wrong drive ratio in the unit on the rear wheel. It may for instance be meant for a larger wheel then the one you have. If it is correct for your bike you will need to have the speedo recalibrated.
I had a similar problem with my 70 T120R. I removed the speedo cable at the rear wheel, rotated the wheel one revolution to see the ratio. I found a calc somewhere or info saying the ratio of the speedo. Bought the correct drive for the rear wheel and now spot on. If I can find it, I'll post more.
Checked the ratio at the speedo gear unit, using the matchstick method as advised by Hoogerbooger back in November and by Rupert Ratio on his book. Ratio is 2:1, which is correct, so my problem must be at the clock end, which is almost certainly beyond my abilities. Thanks anyway everyone. Phil