Speedo Calibration

brewsky · Post by **brewsky** » Fri Nov 20, 2009 5:58 pm

After a loud case of whacky speedo, I decided to take mine apart and see what gave.

Cleaned up all the rust and other gook inside, lubed as best I could and put it back together. Didn't remove the needle since it seemed pretty well stuck and I was afraid I would break it. So I wasn't able to completely dis-assemble the gears.

Hooked up my drill to check it and seems to work fine....no noise, no jumping needle, smooth and quiet.

The only problem is the speedo face says "60 MPH = 2250 RPM", and when my drill is maxed out at 1350 RPM, the speedo reads 85 MPH.

Does anyone know if the referenced 2250 RPM is in fact the required cable speed?

If so, looks like some calibration is needed.

Tweaking the spring stop does affect the reading, but if you move the stop, the needle would have to be re-zeroed.

Also don't know if the needle shaft is just a smooth press fit or if it has splines.

Haven't put it back on yet to check speedo reading vs GPS

mike69 · Post by **mike69** » Fri Nov 20, 2009 7:04 pm

Had the same problem when I lubricated my Dream speedometer.
Too heavy an oil creates a drag.
Clean out the speedo with brake kleen and re-lube with the lightest oil you can find.

rustywrench · Post by **rustywrench** » Fri Nov 20, 2009 7:06 pm

I can't tell you about the RPM factor but my drill runs the speedo about 27 mph and as far as I can tell the bike seems to be traveling about the right speed. Haven't been able to compare it to another moving vehicle.

The needle does not have splines and will come off the post with a flat screwdriver and something under it to protect the dial face. For minor zero adjustments one can move the stop peg in the rear works.

It sounds like you have a pretty good handle on things. I might add that the hardest part of this whole thing was re-clinching the bezel and not messing it up. I used a length of duct tape around a channel lock and gently pushed the flange back thereby not marring the bezel. Ride hard,,,,,RW

brewsky · Post by **brewsky** » Fri Nov 20, 2009 8:22 pm

Thanks for the replies.
Rusty, the max drill speed is normally shown somewhere on the drill for no load.
So if your drill speed maxes out at say 1200 rpm, your speedo is probably much closer to reality than mine if the 2250 is cable RPM. Do you have a CA or CB?

Mike, were you able to remove your needle? I'm guessing CA and CB's are different.
I tried to remove mine by pulling straight out with hook pliers that caught behind the needle center, but the dish shape of the needle center started to bend, so I stopped.

mike69 · Post by **mike69** » Fri Nov 20, 2009 9:09 pm

I didn't remove the needle on mine. I just soaked the unit in penetrating oil and worked it with a drill until it was freed.
I then cleaned it out and lubed all moving parts. I put it back together and test rode the bike and like you said the speedo read much higher than the actual speed.
Took it back apart cleaned it out with brake clean and used a much lighter oil and that fixed the problem.

brewsky · Post by **brewsky** » Fri Nov 20, 2009 10:34 pm

Thanks Mike, I think I will go ahead and do that before I re-install mine.
Looks like you saved me some time!!

rustywrench · Post by **rustywrench** » Sat Nov 21, 2009 1:03 am

Brewsky,
At this time I'm pretty much only into the cl's and I did use a very light oil I use on my fishing reels. I'm sure that makes a big difference. ride em hard. RW

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