GPz1100B2 Slow Speedo.

[BAFF1960]

Hi.

Out for a ride today and came across a road work section restricted to 40mph. I matched the traffic and noticed I was only indication 26. A bit later on an open stretch zipped up to 5000rpm in top which should be about 80 but indicated only 50.
The bikes standard with 19" wheel, Avon Roadrider tyre size 100/90 and a sound speedo drive and cable.
The bikes a German import that came with a mph speedo showing 20K which I think is accurate. It had been stored for 10 years but not in optimum conditions before it came into my possession.
I'm thinking this is a speedo restriction/lubrication issue due to age and condition. Anyone had similar issues?

Alan

[warren3200gt]

Thought gpz had electrical guage not cable?

[Robw]

B1 is electronic and b2 is cable driven
Rob

[BAFF1960]

Hi.

Properly not a common issue but after looking at the speedo and came across this defect.
The upper cable connecting housing/drive magnet support was loose in the lower body, rocking about by a mm. Its a cast item that's swaged to the speedo body. With the weight of the cable levering on it it closed the clearance at the drive magnet and its drive gear. This produced stiff spot in its rotation which stopped the drive magnet reaching its full speed - hence the low reading.
It's probably had a knock or load but on it in the past to loosen the swage. I know from experience not to fiddle with old zinc castings as the get very brittle so tightening the swage was a no go and total disassembly of the clock would be required access . To load the support in the correct position I drilled a couple of small holes in the speedo mechanism steel support and wire locked around the cable housing. Result no stiff spot and the fix is all hidden in the binnacle.

Alan