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Just wondering........It seems to me when mine says 65mph it only going 55. It might be close up to 50 but gets farther off the faster I go. Am I nuts?



Owen
 

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Just wondering........It seems to me when mine says 65mph it only going 55. It might be close up to 50 but gets farther off the faster I go. Am I nuts?



Owen
If it is all stock Yours is off more than most. Most seem to be off. I carry a GPS and use the MPH on it. Jim
 

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Mine is off as well, maybe not as much as yours but it's off about 4 mph low at 65. I've added a new instrument cluster, one of the two popular models, to the list of mods. I'll be adding a GPS prior to that for a few upcoming trips.
 

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Mine is exactly 10% off, less than GPS.

It has differences on all the speed range, from 10 to above.

So, if gps is not mounted on the bike I do calculate it 10% plus speed.

These are my appoximate speedo speed limit for my bike to prevent ticket ha ha ha

My other street bike has same speed error too.

* 35 zone >> 40 (actual/gps speed: 36)

* 45 zone >> 50 (actual/gps speed: 45)

* 55 zone >> 60 (actual/gps speed: 54)

* 65 zone >> 70 to 75 on speedo (actual/gps speed: 63 to 67)

* other >> not tried yet... ^^; ha ha ha
 

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According to the sheriff's radar on the side of the road, I am off about 5mph at 50mph (Actual speed 45)



I also had an error on my speedo, but it was caused by crashing it. On my way home from up north it started wobbling and then wouldn't go above 45mph regardless of how fast I went. It finally died and wouldn't go above 0. I pushed the cable up a bit and it jumped up to my speed once again. I just have to get in there and tighten things down a bit.
 

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Speedometer calibration. If you're interested, here is a table of how fast you are going in 1 min based on each mph listed. I got this from a online speed, distance and time calculator should you want to calibrate your speedo's.



MPH = Time (min in 1 mile)



15 = 4:00



20 = 3:00



25 = 2:24



30 = 2:00



35 = 1:43



40 = 1:30



45 = 1:20



50 = 1:12



55 = 1:05



60 = 1:00



65 = 0:56



70 = 0:52



75 = 0:48
 

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I have the opposite problem. When my tach reads 9000 rpm and using http://www.it-ideas.net/bike/calc.htm to calculate the speed (55t sprocket) the speedo should read 64 mph. Instead it reads 55 mph and on cold days the needle is very bouncy. So, is the speedometer wrong or is the tach? My money says the speedometer.



What to do? Well, nothing. I just go with the flow.
 

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Mine reads 3 mph faster than the actual speed above 30. It is accurate up to 30 mph.
 

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I remember this topic in a thread on the old server. The consensus was...



1) Odometers are geared. There is no room for slop. Changing the diameter of the front tire will change it's accuracy, but not by much. So even if your speedometer is off the odometer probably is accurate.



2) Needle indicating speedometers have the "slippage" factor where the needle position is determined by opposing forces of friction and spring. This allows for error in mass assembly situations or aging units. The unit would be "tested" at the factory, and if it was within tolerance, shipped. But just what is acceptable tolerance is up for debate. (apparently +/- 10% at least)



3) Digital speedometers would be easier to calibrate and therefore more accurate because they show the mathematical result of the odometer feed and an internal clock. No slippage involved.







Personally I will always believe the GPS to be the most accurate method of determining speed.
 

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After almost 5 years, Yamaha STILL has these speedometers mis-calibrated by 10%. I base this on my new TW200 and my GPS. 50mph on speedometer is actual 45mph GPS.

Odometer is off by less, but still not accurate. 3% off. Is anyone using an aftermarket digital speedometer? I'd like to get one with a tach built in as well. If not, I'll invent that wheel and put together something that doesn't lie to the operator what speed or mileage is accumulating.
Yes search VIPER
 

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I personally have never owned one that's totally accurate on any motorcycle, they are all off. My Ducati is a great example, digital speedo and it's still off. Ducati has it actually documented in the manual that the speedo will read 8% faster than you are actually going.


Sent from my iPad using Tapatalk
 

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Now you folks have made me curious about accuracy. To complicate things I have a taller front tire (IRC Trials GP-1). Time to use cell phone's GPS speedo.
 

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Translating into Canadian for my fellow Northeners. 55mph or 88 kph on my Garmin GPS would register 94 kph on my speedo. Also, for reference, 100 kph on the speedo was only 94 kph in reality, therefore 6% error. My max speed of 119 kph with stock gearing and 200 lb pilot was in reality only 112 kph or 70 mph.
 

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My max speed of 119 kph with stock gearing and 200 lb pilot was in reality only 112 kph or 70 mph.
not sure what more you want, or could expect, out of your poor little 200cc?
 
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