XJ550 1982 Maxim: Speedometer needle lagging

Today is the first time out since the Polar Vortex and the Endless Winter of Chicago. My bike was covered, but outside, so expect weird corrosion problems.

My speedometer is correct, but it is slow getting there. In other words if I gun it to 55mph to get on the freeway, it slowly creeps up over about 6 second to 55mph. I am already passing cars and it is only getting past 30mph, but a few seconds later, it is reading 55mph.

Likewise when I come off the ramp to a red light. My bike will come to a complete stop with my feet on the ground, and it takes about 6 seconds for fall completely to 0 mph.

Background: just replaced the front wheel bearings and inner tube. Don't think it should give this behavior... but just putting the info out there.

Can you suggest a fix? Lubrication? How do speedometers work anyway? How can I come to a complete stop and it still be at 30 mph and falling?

(Engine is running like a top however!)

 

Thanks to Big Fitz you can find out how they work by clicking here.

 

Maybe my magnet is getting weak?

 

Read the article linked to above. Your speedo probably just needs to be lubed.