I recently bought a 1999 1200-S. The bike is in excellent condition and has 18k miles. Yesterday I installed a power port for my iPhone so I'd have navigation. Today I went for a ride and compared my speedometer to the GPS. At lower speeds the speedo is reading 12 mph slower than the GPS (at 30 mph the GPS says 42 mph). At 40 mph on the speedo the GPS is reading 59, so the problem gets worse as speed increases. Obviously a problem that I want to correct.

Is there anything I can do about this or is this something dealer need to do? I have a FSM but thought you guys could give me a running start on what I should do about this.

Thanks for your help & suggestions!

 

Buy a new phone....

Or, check to see if the original tires have been replaces with taller tires. If so it will throw the speedo off.

 

Thanks Cricket. Yes the tires are stock sizes. No issues with Waze or my phone in any of our other vehicles. And the bike definitely feels like its going faster than indicated.

And I don't know if it matters, but I worked on the bike this weekend. I replaced the coil & wires and plugs. Removed the tank to do so. Also ran the Powerlet cord for the phone direct to the battery. I'm wondering could I have done accidentally done something while working. I was working slow and careful and didn't have any Oh **** moments.

I did find this recalibration kit at JP Cycles. Anybody ever used something like this tool?
https://www.jpcycles.com/product/560...bration-module

Thanks!

 

Just a stupid question, but are you sure both units are reading MPH. The differences are almost far enough apart as if the speedo was reading MPH while the GPS was reading KPH. With the speedo reading 3 MPH fast, 27 MPH = 43 KPH. 37 MPH = 59 KPH.

 

 

Thanks. I did check the Waze setting and it's in MPH.

 

Thanks. I'm going to check with the previous owner, but the bike is still very stock. I don't think he made those types of changes.

 

I installed a SpeedoDRD on a Honda after changing the gearing, worked great and made the speedo dead accurate. 40% is a BIG error, much more than a gearing change would cause though....I'd guess that probably something is wrong with either the sender or the speedo itself.

http://shop.12oclocklabs.com/index.php?route=product/product&path=31&product_id=59

 

After doing some web research, it seems I should be looking at the speed sensor. Some say to clean it first, but many say it fails shortly after the cleaning and they have to replace anyway. Thoughts?