Inaccurate Speed on Speedometer


Information and questions on GL1100 Goldwings (1980-1983)
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Billthebulldog
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Joined: Mon Jun 01, 2020 10:01 pm
Location: Oshkosh, Wisconsin
Motorcycle: 1983 Honda NightHawk 650 (Sold)
1983 Honda Goldwing Aspencade GL1100A (Current)

Inaccurate Speed on Speedometer

Post by Billthebulldog »



Hello all! I have a 1983 Gl1100a which has the digital dash and I recently came upon a discrepancy with it. It seems that my speedometer is inaccurate by 5mph (Going 75 but reading 80 mph) and I was wondering if there was a way to calibrate it? Do I need to get a new wheel speed sensor? (If so does anyone have one? I can't seem to find any online.) Additionally, what are the consequences of not replacing it? I am very novice when it comes to how these sensors work and what their effect on the bike is. I appreciate all the help!

Stay safe everyone and happy riding!


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Joneszy
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Location: Manitoba Canada
Motorcycle: 1983 GL1100A Aspencade Stripped
1999 Valkyrie CT
1978 Gl1000 "Trickster"
1979 Suzuki GS850(current project)

Re: Inaccurate Speed on Speedometer

Post by Joneszy »

I have three different Honda's, it seems Mr. Honda was overoptimistic when setting up his bikes. All of my bikes and two of my buds Gl's are out by at least that much at the speeds you are talking about. There is no harm done and I merely reprogrammed my noggin to compensate. I don't think there is any way to re-calibrate your digital set-up and a new speed sensor is likely to have built in error as well. Just my 2 cents worth.
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Wilcoy02
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1983 GL1100I frame with an 80 engine. poor boy installed with C-5 ignition--DIED in Grande Prairie Alberta Canada 8/15


98 valkyrie sold 8/16

Re: Inaccurate Speed on Speedometer

Post by Wilcoy02 »

Mine is the same. The 2 other wings I have had never had an accurate reading
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newday777
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1983 GL1100A Wineberry 36,000 miles

1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: Inaccurate Speed on Speedometer

Post by newday777 »

Billthebulldog wrote: Mon Mar 08, 2021 3:06 pm Hello all! I have a 1983 Gl1100a which has the digital dash and I recently came upon a discrepancy with it. It seems that my speedometer is inaccurate by 5mph (Going 75 but reading 80 mph) and I was wondering if there was a way to calibrate it? Do I need to get a new wheel speed sensor? (If so does anyone have one? I can't seem to find any online.) Additionally, what are the consequences of not replacing it? I am very novice when it comes to how these sensors work and what their effect on the bike is. I appreciate all the help!

Stay safe everyone and happy riding!
5 mph is not bad according to the known accepted motorcycle industry standard of 10% off.... Even modern bikes are off unless they are GPS controlled. Variables in tire diameters between tire manufacturers of the same mc tire size, people putting on different size tires than the original tire that came on the bike also play into the factors.
How did you figure out yours is off?

Facts about your 83 Aspencade... Honda was getting into the digital age in 1983 and getting more into marketing the bigger touring bikes to fit the demands of the larger Americans wanting a more comfortable bike to ride to fit their oversized bodies of the rider and their passenger. 83 was the last year of the short 3 year stint the gl1100 was made. 1984 the gl1200 came out for it's 4 year stint before the gl1500 came out in 88. In those 9 years there were many changes Honda introduced in each model and among year to year changes.
The digital dash and speed sensor, among many other parts on the 83A, are 1 year only and also the 1 model only wonders Honda built into the 83 Aspencade. Finding a new sensor will be like searching for a lost needle in a 30' tall haystack the size of Texas.
Be very careful of handling the sensor. Don't break it. Used will be the only source for another.
Very few people have delved in to know how the dash and speed sensor works and if there is an adjustment as there are pc boards in the sensor and the dash. Probably not. The bike has no computer on it so there isn't anything effected by the discrepancy other than actual speed and how many actual miles over the life of the bike. Get a GPS to put on the bike or a smart phone with an app to monitor speed if your want more accurate speed monitoring.
I did some reading on it in the 2009-2011 period when I first got my 83A and brought it back to life after it sat 13 years. I don't know if the electronic wizard that Wingadmin of this sight had delved into the workings on his 83A speedo while he had it. There was more information on the digital dash on the goldwingfacts .com forum back then, but I left that site back in 2013 when it got bought out by a dotcom conglomerate that totally screwed the pooch.
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Billthebulldog
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Location: Oshkosh, Wisconsin
Motorcycle: 1983 Honda NightHawk 650 (Sold)
1983 Honda Goldwing Aspencade GL1100A (Current)

Re: Inaccurate Speed on Speedometer

Post by Billthebulldog »

Thanks for all the great information! I'm glad to find out I'm not the only one!
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Maz
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Re: Inaccurate Speed on Speedometer

Post by Maz »

GPS speed is supposed to be extremely accurate, however, I've found this not to always be the case. I work with Police Vehicles and part of my job used to be installing speed detection systems. These work by measuring time and distance and had to be calibrated at the start of every shift, to take into account variances in tyre pressures, load etc. The vehicles had to be driven over a certified mile distance (marked on the motorway shoulder with brass studs at start and finish by accredited government surveyors). The number of pulses generated by the vehicles Speedo pulse generator over this calibrated mile was then programmed into the system. I often ran a GPS Speedo alongside the system and it was very rarely the same. Usually, the GPS was 3 - 5 mph slower.

Maz
Ironically, Common Sense is the LEAST common of all senses!
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AZgl1800
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My son is going to enjoy it for many years to come.

Re: Inaccurate Speed on Speedometer

Post by AZgl1800 »

I will trust the GPS reported speed a whole lot more, than any "trip elapsed time" over a measured mile course.

the GPS signals are timed to the nano-second, not so the throttle on your patrol car, no one can hold it at a specified speed accurately over more than a few seconds.

Radar are supposed to be calibrated against a "Tuning fork", not elapsed time over a road course.

as for the speedo on my 1800, it is off at least 10% more than the real speed.

at 70 GPS, it is how 77+
~John

'02 GL1800
2009 Piaggio MP3 250cc
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Maz
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1993 Suzuki GS500E

Re: Inaccurate Speed on Speedometer

Post by Maz »

AZgl1800 wrote: Wed Mar 10, 2021 5:31 pm I will trust the GPS reported speed a whole lot more, than any "trip elapsed time" over a measured mile course.

the GPS signals are timed to the nano-second, not so the throttle on your patrol car, no one can hold it at a specified speed accurately over more than a few seconds.

Radar are supposed to be calibrated against a "Tuning fork", not elapsed time over a road course.

as for the speedo on my 1800, it is off at least 10% more than the real speed.

at 70 GPS, it is how 77+
I may have not explained that correctly.
The certified mile distance is used to measure how many pulses per mile the particular vehicle produces (in the case of a Land Rover Discovery, approx 28,000). The system can, obviously, be used to measure the speed of other vehicles, by counting the number of pulses between any two points, chosen by the operator, against an electronically measured time period. The speed of the patrol car can vary as much as you like, as the system is purely using the patrol car to measure distance (pulses) against the time it takes the target car to cover the same distance. However, what I am saying is that there is a constantly running electronic digital speedo, separate to the time/distance calculating function. This operates next to the original vehicle analogue speedo (which, in itself, has been government calibrated) at all times, and is calibrated using the measured mile as above. This speedo knows how many pulses equal 1 mile (cos you have measured it and input that number yourself, for each vehicle) and measures that against a digital electronic timer unit (as used in the most accurate watches/clocks/timers available) to display true vehicle speed.
Yes, Radar is a different animal and is, indeed, calibrated using a tuning fork.
My only other point would be, have you ever looked at your Sat Nav device and noticed you are not EXACTLY where it says you are, especially in a built up area?
Have you got a GPS Tracker on your vehicle and tracked it online, only to discover that you are not EXACTLY where it shows you to be, or the icon suddenly relocates a little bit? This is due to signal bounce, around obstacles (buildings etc). What IS truly accurate?
Back to the original question, I wouldn't worry about the 5mph misread - Perfectly normal.

Maz
Ironically, Common Sense is the LEAST common of all senses!
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AZgl1800
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'02 GL1800 lives in Dawsonville, GA now.
My son is going to enjoy it for many years to come.

Re: Inaccurate Speed on Speedometer

Post by AZgl1800 »

Maz wrote: Thu Mar 11, 2021 3:11 am
AZgl1800 wrote: Wed Mar 10, 2021 5:31 pm I will trust the GPS reported speed a whole lot more, than any "trip elapsed time" over a measured mile course.

the GPS signals are timed to the nano-second, not so the throttle on your patrol car, no one can hold it at a specified speed accurately over more than a few seconds.

Radar are supposed to be calibrated against a "Tuning fork", not elapsed time over a road course.

as for the speedo on my 1800, it is off at least 10% more than the real speed.

at 70 GPS, it is how 77+
I may have not explained that correctly.
The certified mile distance is used to measure how many pulses per mile the particular vehicle produces (in the case of a Land Rover Discovery, approx 28,000). The system can, obviously, be used to measure the speed of other vehicles, by counting the number of pulses between any two points, chosen by the operator, against an electronically measured time period. The speed of the patrol car can vary as much as you like, as the system is purely using the patrol car to measure distance (pulses) against the time it takes the target car to cover the same distance. However, what I am saying is that there is a constantly running electronic digital speedo, separate to the time/distance calculating function. This operates next to the original vehicle analogue speedo (which, in itself, has been government calibrated) at all times, and is calibrated using the measured mile as above. This speedo knows how many pulses equal 1 mile (cos you have measured it and input that number yourself, for each vehicle) and measures that against a digital electronic timer unit (as used in the most accurate watches/clocks/timers available) to display true vehicle speed.
Yes, Radar is a different animal and is, indeed, calibrated using a tuning fork.
My only other point would be, have you ever looked at your Sat Nav device and noticed you are not EXACTLY where it says you are, especially in a built up area?
Have you got a GPS Tracker on your vehicle and tracked it online, only to discover that you are not EXACTLY where it shows you to be, or the icon suddenly relocates a little bit? This is due to signal bounce, around obstacles (buildings etc). What IS truly accurate?
Back to the original question, I wouldn't worry about the 5mph misread - Perfectly normal.

Maz
oh yes,
have noticed that the GPS's exact location can shift around...

that is designed into the civilian accessible GPS system for military purposes, to make the exact missile pointing point imprecise.

and yes, if you are in a city area, where the building block a clear sky, the GPS signals do bounce around a bit causing errors.

On the open highways, that is usually NOT the case, as I was interpreting your initial post.
So, for me on my bike/car I always use the GPS.... the displayed MPH is rarely off by more than 1 mph.

Just yesterday, I was driving a strange vehicle ( neighbor's car ) to town to do her shopping run.
I wanted to verify her truck's speed error.... was a bit shocked to note that it was '0' mph versus my cellphone's Speedo display.

On my Suburban with oversize tires, it is off by 4 mph in the positive direction, so 65 indicated means the truck is running 69.... as the GPS is always on the dash of our vehicles, I verify my speed by the GPS to prevent acquiring a "safety award" :mrgreen:

I have an electronics background that has covered my entire avocation career starting back in 1958.
Studied the calculations pertaining to GPS may times. GPS was not a thing in 1958 though :lol:


~John

'02 GL1800
2009 Piaggio MP3 250cc
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