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Speedometer/Odometer accuracy

7K views 19 replies 12 participants last post by  Cherokee Bill 
#1 · (Edited)
I recently got a gps mounted on my c109 and checked the speedometer accuracy and as expected it was off by about +7%. e.g. at 70mph the GPS read 65mph. I also checked the odometer on a 100 mile trip and found it off by 2.65% (Bike odometer 100.6 miles, GPS 98.0)

see the attached pic for my calculations

There are numerous post about the m109 speedometer accuracy:

post 1
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#4 ·
I'm trying to look up the statute now but it was my understanding that an odometer may be up to 4% off before it is considered illegal. In the event that a vehicle is purchased with a faulty odometer (ie. one that reads in excess of 4% error) the manufacturer must replace the faulty equipment FREE OF CHARGE in order to meet the requirements by law.​

...other than that, you'll just have to deal with it...:eek:
 
#5 ·
I'm sure it's within legal tolerances and this post was more informative than anything. You can install the SpeedoHealer from HealTech to fix calibrate the speedo. But then you get into which do I calibrate the odometer or the speedometer...Oh well!
 
#6 ·
Last I was aware of the Law accepted +-10% in my area.

I know fixed and mobile radar are set at that. ie 110kl/h in a 100 zone ok
111kl/h in a 100... toast.
Doesn't mean you can't get pulled over for less as I have...Only a tiny percentage go to court to contest it, but as far as radar and acceptance in court +-10% I'm told.
 
#8 · (Edited)
[quote
BamBam70, are you sure that percentage is regaurding your odometer and not simply your speedometer? I agree that 10% is a reasonable amount of error for a speedometer but I'm pretty sure that that is well above the legal limit for an odometer in just about any location. ;)[/quote]

No I'm not, however isn't the odometer related to the spedo on vehicles?

I'm only confident of speed camera and radar settings
 
#11 · (Edited)
I was under the impression that the Speedohealer was inserted between the output shaft sensor and the insturment cluster and assumed that it would simultanously adjust the speedometer and the odometer by the same amount. Are there separate sensors/wires for the odometer/speedometer?
There are many occasions where the speedometer and odometer run off of the same cable/sensor but in this case the speedometer can only have so much of a calculated error in order to stay within the guidelines for which the odometer must abide. Short of looking over some paperwork I believe this question has been discussed in a previous thread. It was noted that the M109R has a separate sensor for the speedometer and odometer.​
 
#12 ·
I was told that all motorcycles are 5 mph off. When your going 65 on sppedo your really going 60mph. I have checked several different styles and several different makes... Holds true...
This may have been the result of your findings but this is not always the case. I have worked on and serviced many, many motorcycles and I have found that some are dead on while some have a percentage of error. This is commonly the decision of the builder/manufacturing company.​
 
#13 ·
For example my GPS true speed at 70mph and my bike speedo will be at 63/64mph.

Also I rode last Saturday and my ODO stated 185 miles at the end of the day. My girlfriend rode directly next to me on her HD all day long and her ODO stated 180.2 miles.

I'm not really sure what's so difficult about Suzuki not making an accurate speedometer. If you can get an aftermarket "speedo healer" then why can't that same technology simply be installed by the factory in the first place?
 
#14 · (Edited)
error

I recently got a gps mounted on my c109 and checked the speedometer accuracy and as expected it was off by about +7%. e.g. at 70mph the GPS read 65mph. I also checked the odometer on a 100 mile trip and found it off by 2.65% (Bike odometer 100.6 miles, GPS 98.0)

see the attached pic for my calculations

There are numerous post about the m109 speedometer accuracy: example my 3 buddy's all have m109, all 4 of us are with 2%
of each other on both speed and miles. we all see a difference which is greater at lower speeds and becomes very close to real speed at high speed ( 85-110 ) can't speak for the c109, but I really don't care if it off by 3 or 7, even 10, I personally am very
seldom at the posted speed anyways....as with most 109 riders I've meet since 2006 when I got mine...

post 1
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recheck your math - the error percentage appear wrong
 
#16 ·
putting a 260 Metz on the back makes it only a 2% error.(compared to my GPS anyway) 65 sdo is 64 GPS. Close enough for government work.

Ah but now the odo is 2% slow. can't win em all. :doorag:
lol I think I like those numbers regardless; not everyone has the money to blow on a Heal Tech Speedo Healer! :bigthumbsup:
 
#18 ·
I'm glad you dug this post up; as a new C109RT rider, and with mine having low miles, I'm going to order the SpeedoHealer today, and I'd like to know where to plug it in as well. ???
 
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