Digital Speedos

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Constant Mesh

Well-known member
FJR Supporter
Joined
Jul 11, 2005
Messages
1,802
Reaction score
65
Location
Tenn
These have two attributes that I really like --

There's not an analog dial with a higher than possible max speed. I detest speedos which max out at absurd speeds while offering a very small sweep of the needle for normal speeds.

A digital speedo offers only mph or kph, not both simultaneously. Showing both on analog dials adds unnecessary clutter and distraction.

 
The kph scale on the needle gauge was darn difficult to use because the numbers were small and the scale was too small to provide good speed resolution at a glance. I opted to change the GPS to kph and use that as my speedometer in Canada. Most of the Canadian roads have speed limits unrealistically low and the speed enforcement is unrealistically tight with terrible punishment for small infractions so the need for a good kph speedometer (IMO) is important. I now have a good solution, accessible on the menu page
smile.png
so I can relax while visiting the frostbacks at CFR.

 
Last edited by a moderator:
Interesting statement, I'll paraphrase what I heard you say: "I like digital speedometers because they don't show a speed I can't possibly go, and they don't show MPH and KPH at the same time."

Well, I like analog because it shows trends at a glance, and they give me hope that one day, if it try real hard, I could go insanely fast.

 
Last edited by a moderator:
I gave up looking at the speedo, and now only use the GPS. If the GPS fails, I'd probably go with the seat of my pants scale.

 
Most bike speedos are too inaccurate, so I use the GPS. The digital on the GenIII is too big and distracting given it is 7% off. I'd consider a speedo healer. Rumour has it the '17 speedo is much better for accuracy?

 
radiummadman posted: 2004 FJR is +3%, 2013 Super T is +8% do a little math & be cool
.... and if you go 100 mph, the math is really easy.

 
Last edited by a moderator:
Don't understand why the designers build in so much speedo error?

They obviously care much more about odo accuracy.

I assume the same data input drives both meters.

One wonders about the accuracy of the tach? Are they playing games with engine speed too?

With the gear ratios and rear tire circumference one should be able to relate speed and rpm. But, which meter do you trust?

 
...One wonders about the accuracy of the tach?...But, which meter do you trust?
Put a mechanic's tach or a timing/tach light on the engine and check it. Set the timer on your phone/camera and put it in fridge, wait for the click then look at the picture to see if the light went off when the door closed.

 
Don't understand why the designers build in so much speedo error?...One wonders about the accuracy of the tach? Are they playing games with engine speed too?

...
At least in the UK, manufacturers are required by law to make the speedometer never indicate a lower speed than the vehicle is travelling. The manufacturer inevitably errs on the side of caution, allowing for any likely tyre and wear plus any inaccuracy in the speedometer itself.

My '14 reads something like 10% fast, the worst of any vehicle I've been able to calibrate.

 
The speedometer and odometer on my 2014 A are 2% optimistic (50mph indicated, 49mph actual), very close to dead on.

Dan

 
Last edited by a moderator:
I'm too old to see the numbers on my analog speedometer on my 2008 FJR1300AE without reading glasses.

Does anyone know if a digital speedometer from a 2014 model FJR works if swapped with the analog one on my 2008?

Connector/wiring issues?

Thanks

 
I'm too old to see the numbers on my analog speedometer on my 2008 FJR1300AE without reading glasses.Does anyone know if a digital speedometer from a 2014 model FJR works if swapped with the analog one on my 2008?

Connector/wiring issues?

Thanks
Only one way to find out! :)

But I'm guessing you can't just swap it out. The Gen 3 clusters had a menu system built in with different controls. But with the wiring diagrams, I bet you could come up with something if you're so inclined. It'd be easier to buy the Gen 3 cluster with the rest of the bike attached though.

I used to design software for snowmobile, motorcycle, atv, etc. gauges. Arctic Cat was my big customer. We had an analog gauge which was deemed too expensive and reserved for their higher end models. We made a low-cost version that was just an LCD. The had a huge demand for those gauges. People were swapping the analog one for the low cost one because they assumed it was better and more high tech because it was digital.

Don't understand why the designers build in so much speedo error?
They obviously care much more about odo accuracy.

I assume the same data input drives both meters.

One wonders about the accuracy of the tach? Are they playing games with engine speed too?

With the gear ratios and rear tire circumference one should be able to relate speed and rpm. But, which meter do you trust?
There are a few issues at play when it comes to speed / odometer accuracy. First, they come from the same signal. The ABS senses pulses and there are a certain number of pulses per mile. Counting pulses is easy. Get over the pulse per mile setting and increment the odometer by 1. Measuring the time between pulses is more difficult. The microprocessor can detect these pulses at a certain resolution. The tradeoff is the higher resolution means the less time you have to sample those pulses. That makes your sample size at slower speed much smaller. It also doesn't produce a good user experience because the speed would jump around all the time. That pulse signal is also not clean. There are transients and spikes that can register as pulses causing speed to read higher.

The second issue is cost. You can get an 8-bit micro for pennies vs a 32 bit micro that for dollars. In the automotive world, that's a no brainer. There's a saturation factor too where you could have Watson on your bike, but if your signal isn't perfect, you're not getting anything better. Garbage In, Garbage out. Things like Speedo Healers just condition that signal to read 5% slower or whatever you configure it to. It isn't fixing the signal, it is just compensating for your bike. That's something that differs from bike to bike.

The last thing, and maybe the biggest reason, is legality. Odometer is a legal measurement and it's better to be high than low. In fact, it is illegal to be low. Most instruments have a spec of +/- 5-10%.. Odometer accuracy has a 0% - 2% of scale requirement. That means if the scale of your odometer is 100,000 miles, your accuracy can be off by 2,000 miles at any point and be considered within spec. The FJR could be off by a factor of 20,000 miles and still be in spec. We always tried to be as accurate as possible, but being low on odometer was unforgivable. On larger vehicles (RVs, firetrucks, etc) the odometer is broadcast by the engine. The engine manufacturers prohibited us from just displaying that value. It was grounds for a lawsuit that we would most definitely lose. Our workaround was taking the difference between the current message and the previous message and adding that to our own odometer count.

TL;DR - Swapping out clusters is likely not possible without a lot of work and understanding of the electronics. Speedos are inaccurate high because odometers can't read low.

 
I have an older Tom Tom GPS installed with a program that shows digital speed (nice large numerals) , compass direction, max speed, average speed, Odometer, etc etc. It works great and is very accurate. The program that is installed and providing that info is called TripMaster. Check it out on the web.

 
Top