5th Gen Speedometer Error - In Pictures

I know that motorcycle speedometers are typically off, and I have read lots of discussions about this topic. After getting my GPS installed I finally know how much mine is actually off (stock gearing).





I haven't decided if I will eventually get a Speedohealer, but it's nice to have a better idea of my actual speed now!

 

speedo

WOW -- pretty good pictures!
My speedo reads about 10 mph high at 70mph, I wonder if it varies with
age (68k mi)?
Happy trails

 

What is that switch on the left side fairing trim piece just behind the mirror bolt?

KC-10 FE out...
lane: :usa2:

 

That's for my grip heaters.

 

Does speedo error also make for mileage error (thus throwing off all our MPG calculations)? I was under the impression that it would. My uncle didn't seem to think so. Thought it was a conspiracy to keep motorcyclists from going to fast. So "they" just messed with the speedo, and not the odometer.

 

Can you link me to where you got your GPS mount?

 

RAM features gps garmin mounts for airplanes trucks vehicles motorcycles autos streetpilot quest etrex

This may be the right answer,mine ram mount for tom tom works perfect.

 

Looks like we get the same readings Britt. As for the odometer, it appears to be right on.
I see 125 in the max speed window, you've been having fun!! .....hee hee

 

That must have been an odd reflection on my GPS when I snapped that picture, for I would never dream of riding at such speeds on a flat wide open stretch of road... :angel:

 

I did a writeup on my setup that may be helpful to you.

http://vfrworld.com/forums/body-accessory-reviews/18599-ram-tank-mount-garmin-nuvi.html

 

5-10%

yeah looks like everything I;ve read correlates with your gps experiment, 5-10% faster than you're actually going, thanks for the nice pics and info.

 

I've noticed this too, exact same margin of error as Britt. From my GPS tests I can also say the odometer/trip-meter is perfectly accurate. Stock gearing BTW. It's almost like it's deliberately inaccurate...

Meanwhile, my two old 1981 budget-bike CX500s are dead accurate, up to their max speed (85mph). You can be darn sure Honda could get the speedo right on something as high-tech as the VFR, especially when the odometer is somehow spot-on. My theory is they set it deliberately high in an attempt to improve rider safety.

 

Wow thought i was going nuts, glad I found this helps me with my head scratching, as at 75 mph traffic was still hanging with me in a 70ph zone that and i was thinking the rpms were a tad high so in this a started to wonder if the owner before me had drop a front tooth or not. this explains what I'm seeing, how odd Honda wasn't able to make it more accurate.

 

LOL I just went through this same exercise this past year. As cars are passing me, I recall the feeling of "what the heck!" too vividly.

I have read in these forums that some countries have rules that the speedometer must read over and that it can absolutely not read under (maybe the above thread has info, I didn't read it all). So they make it read far over the correct value, and they never have a legal problem. I can assure you there is some engineer at Honda screaming bloody murder. Tech guys hate making things wrong on purpose. I have had to program jobs to an incorrect spec to meet my customer's wants. I know how they feel.

I used a speedometer application on my iPhone. I rubber banded the phone to my arm for easing viewing. In my 5th gen with a 16 tooth front sprocket:

at 25 mph it reads 30 mph
at 66 mph it reads 75 mph

If you get the same numbers then we're probably geared the same.

This causes me much distraction as I have to constantly calculate my speed. Around me are areas where the speed is vigorously enforced.

I was thinking about marking the speedo at 25, 35, 60, etc. so I can just look for a green line or such. Maybe a decal on the top of the speedometer, a quarter inch wide, with printed markings?

 

I don't think I've ever owned a Japanese bike that had a speedometer that read the correct speed. They all seem to vary between 7-10%. This goes back to the 70's. Odometers are accurate, but not the speedo. I put a bicycle computer on mine so I know my speed because it was much cheaper than a SpeedoHealer.

 

Knight wrote
" Tech guys hate making things wrong on purpose. I have had to program jobs to an incorrect spec to meet my customer's wants. I know how they feel."

Funny about that, I feel there was a few tech guys at VW who did this very thing:smile-new:

 

The problem is that when the bike is leaning over the wheels would have to rotate faster compared to standing up straight. If you look at how the tire contacts the road when it gets closer to the rim the wheel spins faster (think small wheels) compared to when it's standing up (think big wheel).

So because of that that's why speedometers are not totally accurate, they try to be on the safe side just in case you're leaning over.

 

Very interesting point JD, I'd never thought of that.


Sent from my iPhone using Tapatalk

 

Well hell, guess what I found, LOL a 16tooth sprocket.. ok now I have to figure if it's worth the change, my 4th gen had a factory 16 ,but the 5ths have 17 ?????? Weird as it does bug me, just wasn't feeling right. Have you guys that have swapped out the counter shaft sprocket have enough slack in the chain adjustment? this 5th came with a fairly new chain, only 1500 on it, so not sure how the links were cut giving what mount of slack.

 

Yes the 5th has a 17 then the sixth has a 16. Maybe the 17 was a move to lower the emissions knowing that we would swap it out. Strange that they returned to the 16 although maybe the 6th gen has different gearing (?).

I do a lot of tooling around at 25 - 35 and rarely do over 70 mph or so. The stock bike is geared as a compromise between 25 mph and 140 mph. That meant that I was using a lot of clutch at the stoplights. I have found the 16 to be nice for stoplight launches and to put me in the power band at 5th on the freeway.

I cannot comment on the slack however someone here did a 16 front and +3 rear, so there should be plenty of adjustment to get the 3/4"+ chain movement.