Weird Speedo Behaviour

I finally got a chance and a nice stretch of road to open the 650 up. I had it up to about 90mph and still accelerating when the speedo needle quickly jumps down to around 70 and wouldn't come up again even though I knew I was still accelerating. At first I thought I broke the cable again, but after I slowed down it seemed to behave normally.

What could have caused this? Maybe it's not lubed enough? This is a after market Motion Pro cable, as I snapped the original one last year.

Maybe I just frightened the speedo, as it normally doesn't see those digits. :laugh:

Not that it really affects me as I probably won't be riding that speed again but just curious.

I'd remove the cable,pull the inner cable out,clean,inspect,re-lubricate it, re-install it and go for a ride. Hard to say what caused the needle to stick.

also if you put a drill on the cable and spin it up you will be able to see if it is in the speedo head or possible in the drive down on the front wheel.

Thanks guys. I'll take it off to check the lubrication.

Any recommendations on what lube to use?

HerrDecon. Some thoughts. As i recall, the drive cable of the 650 uses a blade at drive (wheel), and is crimped to core (wrapped wire bit) and is stamped square at speedo drive reciever. check blade for secure fit to cable and that speedo drive driven worm gear is securely located and cannot travel away from drive worm. then . check that fit of square section to speedo reciever is good. poor peneration or worn reciever could cause loss of drive at higher rpms. (common on old english (smith) guages). if this is the case, don't dispair, simply smacking the square section lightly or squeezing in vice usually provides good drive. and last, meter motion is just that, while odometer function is gear driven, the needle is simply a magnetic induction function. it's likely that areas of travel un-used for years are stiff. you might try driving (as prev. post) with a drill to free.(after leaving in sun to warm) resist temptation to lube via aresol. as these usually end up clouding guage/s. Finally. speedo/tach cables like smooth routing.because of their construction, they have the ability to wind-up and un-load at whim, causing bouncy guages. hope this helps. G

Kinda same question... but I have a 76 900 and it seems to be about 10 mph off, and rises exponentially the greater the speed. Just replaced the speedometer cable and all... using GPS right now which is why I know its way off. Any thoughts???

Thanks gane, some great info there. I'll double check everything tonight.

If you find you need your speedo repaired we have a member here(Bob Harrington,Canyon Dancer) that repairs guages.

His site is Z resto. There is a link to his site on z1enterprises. Roy

PS If you have him to restore your guages you will be amazed at the "new look".

Thanks for the contact roy.