Speedo Accuracy

[2and3cylinders]

I've never seen a chain drive motorcycle that took speed from the transmission. Every chain drive bike I've owned used a front wheel sensor for speed. Since the FJ needs wheel speed sensors for ABS and traction control, it makes sense to use that data for speedometer/odo output, too.

I'm a wheelie junkie. With the traction control off I start wheelies in 1st gear and shift in the air through 2nd and someitmes 3rd gear. No way the front wheel can be the source for the speedo since I start at 35 mph and put the tire down at 88 mph when the 2nd gear rev limiter kicks in. I.m going to try two up on the rear sprocket to make 2nd gear lift the wheel a little easier. My best wheelies are on the last gallon of gas in the tank. The bike struggles with 2nd gear wheelies with a full tank. Has anyone tired 2 up on the rear sprocket?
Dennis near Chicago
 
~ djbinchicago, 23 Aug 2016 at 16:17""
 
 
 
I have found the speedo quite accurate based on my cell GPS and Garmin unit.  For those with a dedicated GPS unit most save until reset miles traveled, average mph, travel time AND maximum speed so all you have to watch is the speedo's maximum and remember it long enough to compare it with the GPS.
 
Also, in my medium depth review of the OM I could not discern where the mph is picked up from but I doubt the wheel sensors.  Many motorbikes do read from a tranny based sensor (i.e., my VTR) and I'd think the FZ/FJ/XSR do as well.  Anyone definitively verified what feeds the speedo??
 
As for going two teeth up on the rear sprocket (I prefer not going less than 15 teeth on the front as it over-stresses the chain) that is not that unusual and thus a 47T rear is 4.4% higher numerically (lower in the vernacular) than the OEM 45T. Dropping 1 tooth to a 15T front is 6.6% higher ("lower"), 1.5 times lower (higher numerically ratio wise) than adding two T aft.
 Going to 15/47 = 11.4% lower, which IMO is too much for normal street use.  If the FJ-09 was made dirt worthy (illogical and costly), then 11+% would possibly make sense (but not also including adding a switch to kill the ABS and keep the TC off too).
 
BTW DJB, where near Chicago are you and how old are you?  Not that us elderly folks are not capable of popping the occasional wheelie. (