Speedometer off?

[Krusher]

My wife's '06 kat 600 speedo is off a good bit. actually running 45 MPH it registers at about 60MPH, actually running 65 MPH it registers about 80 MPH. I've also checked the distance between mile marker signs and the registered mileage is off ( I think registered 7 miles in 6 miles). I know right off the bat it has the wrong size tire on the rear (180/55-17 on a 4.5" rim) which makes the profile taller. as far as I knowthe sprocket tooth count is stock. I'm not sure if any gearing internally has been done but it goes through the gears quick and has VERY quick acceleration and tachs up quick. I'm going to wait till I put a new tire on the rear to see how it affects it before I do anything major to fix the speedo but it definitely needs fixed. May have to get a speedo healer.

[The_Incredible_Hulk]

Sounds like gearing is off somewhere to me....

[burrsg101]

600 should have a 15 tooth front and 47 rear sprockets. It probably has different sprockets but it sounds like its also the change in that tire size. A 150/70/17 (our stock size) has an overall circumference of 79.38" and an overall diameter of 25.27" where as that 180/55/17 has a circumference of 77.9" and a diameter of 24.8" so about a 1.8% difference for the speedo so that alone would mean a speedo reading of 60mph would results in you actually traveling 58.9 mph. Not a big difference but its there and gets worse the faster you go. I'd say it probably has a 49 tooth rear sprocket or a 13 or 14 front. Most people just throw rears on though. If you really want to keep it how it is then get a speedo healer, other wise take the stupid 180 off and put a 150 back on (it'll handle way better as well with the 150) and make absolute sure the sprockets are stock.
As for internal gearing being changed, I don't know that there is anyway that that could be even remotely easily done to our bikes so chances are its stock inside.

I've heard a lot of different people saying you need a speedo healer even stock, but i just checked my 06 600 today with a gps and my buddies car and they all three said 60mph at 60mph, 100mph at 100mph, and traveled the same total distance so I'm calling bs on that.

EDIT: Actually I just did some more comparing and even with the smaller diameter tire for it to actually be 15mph off youd have to have a 12 tooth front sprocket with a 50 tooth rear. Try to count the teeth on them and if they arent off then i'd say its time for a new speedo most likely.

[thetable]

Typically, manufacturers build in about a 10% discrepancy on indicated speed versus actual speed. The odometer, however should be pretty close to dead nuts accurate. Get that tire off there, and run at least something close to stock. The 180/55 should only account for about a 5% discrepancy, so I'm guessing the gearing isn't stock.