Speedometer reading is off

[Chomps-Lewis]

Hello Everyone,

Ive gotten my 2001 Hayabusa registered and on the road finally after a lengthy dispute with the DMV. An issue that Ive come across though is it seems my speedometer is incorrect because I was constantly holding up traffic when I went for a rides. I paced alongside my buddies car with cruise on and it seem my speedometer is displaying about 10mph faster than Im actually going.
It seems pretty consistent at least. When it says Im going 40mph Im really going 30mph, when it says Im going 60mph Im really going 50mph and so on.
From browsing the forums it seems that the major solution is to get a speedohealer. But before I spend $100 on one, Id like to ask if there are some things you'd recommend I check out before diving into new parts? could the sensor need cleaning or tightening, or maybe my sprocket gear is aftermarket and the wrong size? that sort of thing. The bike is getting new tires soon so Ill be putting it on the lift anyway, might as well get in there and start troubleshooting.
I appreciate any help.

 

[kml]

They all do that, every single Suzuki
You are correct with your research, a Speedohealer will fix the problem
I've had one for well over a decade with no problems.

https://www.healtech-electronics.com/products/sh/

cheers
ken

 

[Hayabusa Wannabe]

...or maybe my sprocket gear is aftermarket and the wrong size?

I am not sure but I think on this bike the speed sensor measures movement of the front sprocket. If so, smaller front sprockets do exaggerate this speed misreporting. But such would not be a "wrong" size and I would not necessary change it, but merely an accessory. The most common upgrade for sport tourers is a smaller front sprocket to launch the bike off of the line quicker. If so that may contribute to the misreporting (others may be able to verify for this bike.)

 

[Chomps-Lewis]

Alright, Ill look into the speedohealer then. Thanks!

 

[HayaWakened]

Cheap to count the teeth on the front sprocket. My Gen 2 is -1 tooth from OEM (16 from 17?) and runs 10 mph fast, like yours FYI

 

[sixpack577]

Gen1 stock 17/40
Gen2 stock 18/43
Gen3 stock 18/43??