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Check your Speedos!

9.5K views 72 replies 48 participants last post by  jlyben  
#1 ·
Today I done discoverd my Shadow's speedo reads very optimistically! Now its a Metric bike, so I expected it to read a little off. Now I ain't got no GPS that works, I did but it's broke. Now for the most part I seem to be keeping up with traffic, at the indicated speed limits 95% of cars is the same speed so I though it was reasonablly accurate. Also, just buy "feels" alone, it feels very accurate to me.

But today I seed one of them Civics that has them digital speedos [the kind on the dash but its electronic so you can see the speed]. Now I got beside him and was adjusted my speed to be almost exactly the same pace. Then I looked at my speedo and said 59-60 MPH, and when I looked at his it said 50-51 MPH!:shock:

WTF? That makes me SO mad!:evil: Can Honda not design a ******* working speedo or what?:mad: Seriously that is an annoyance. So all this time I've been driving like a gradma?

BUT the thing is, if I go the speeds this would equate to, I feel like I's speeding like a maniak, and always passing cars. What's up with this? I'd love it of any of y'all could tell me what your speedos read to GPS/Radar/Cars?

BTW bikes an 85 Shadow 700.
 
#3 ·
From what I've seen , the bikes are speedo type vs year and mileage put on em. For "majority" of them, 5-10% off on average for up to around 50 mph or so. Usually after that 50 mph mark the % off rises from there getting worse and worse. This is pretty much a metric bike problem across the board. I know, it sucks and I hate it too.
 
#7 ·
When checking the speed in my Honda Civic with GPS, the car will read 65, the GPS says I'm doing 60.
that is done for a reason, and purposly from the factory. back in the late 90's we had some Acura RL speedos that had to be recalibrated at high end of the speedo, due to speeding tix (speedo reading would 59mph and you where actually doing 61)
but 65 to 60 thats a little to far off, driving with a laptop hooked up you usaully see about a 1 mile an hour diff
 
#9 · (Edited)
Thanks to all of you for the quick responses!

gmck, I gotta say myself, thats the best I've herd all week!:-D

Honda-Rider holy hell, it rises more than 10% off at higher speeds?:-x That, alone, drives me frekin CRAZY!


Scrapdog2grand huh, well it wasn't that clear, but it seems it would have been hard to mistake, as we was accelerating all the way from a stoplight. MAYBE, but I kinda doubt the Shadow would read slower than actual speed?

Well sounds like a good reason to buy American bikes! MOst H-Ds read very accurate I've ridden, my dad's 08 Softail Deluxe reads only 1 MPH off the CHP trailor radar. Although some are less accurate than others from what I here.

No but seriously, I think this is completely unacceptible. I would like to take the gauge off my speedo, and put a GPS where it was right now, leaving just the odometer/trip meter [from what I read about Japanese machines, these are not so inaccurate like the speedo].

SO lets see, 80MPH indicated=69 MPH actual by the % that this was readin off of 9 MPH at 60 MPH?:shock: Wow, I usually keep it at 70 MPH indicated on the interstate, its a wander I ain't been run over yet!:eek:


Is it possible to swap out for a bigger rear tire? Or is there no room, a taller tire would slightly help it read more accurate. On trucks I know its a problem with them reading lower than actual speed.

Now if that Civic reads lower?

I wander if my speedo's bad? What RPMs do you guys with 80s Shadow 700/750s turn at at say, 65,70,75,80 MPH indicated? At 65 MPH indicated in 6th I turn around 3,700 or so, 70 is 3.9-4K, 75 is about 4.3K, and 80 is about 4.4-4.5K. Is this what you guys get?
 
#12 ·
I wander if my speedo's bad? What RPMs do you guys with 80s Shadow 700/750s turn at at say, 65,70,75,80 MPH indicated? At 65 MPH indicated in 6th I turn around 3,700 or so, 70 is 3.9-4K, 75 is about 4.3K, and 80 is about 4.4-4.5K. Is this what you guys get?

That's about what I get. 85' VT700c[/QUOTE]



Huh gets its not just mine? Sucks ass! I mean I can deal with it reading 5 MPH higher, but anything after that is no excuse! I wander what the actual RPMs is at those GPS speeds?
 
#22 ·
Mine reads about the same as everyone else, 60 actually is 55. I pass by one of the automatic speed reminder thingys every damn morning, when it actually catches the bike profile, I find that the bike can get pretty much right on top of it before it reads me. Not something I am willing to test with an actual cop car...
Anyway, I thought that if you changed your tire size up, and I don't remember which size it was for my bike, it would correct it pretty close to spot on. Getting the tires changed this weekend to a metzler from stock, will try to remember to repost if the size changed anything.
 
#24 · (Edited)
Speedo Error

The typical speedo error with the stock tire on the shaft drive 750 Aero is 7%. That is with a tire at about 1/2 life. As the tire wears the error increases.

With the 750 Aero we correct that error by going up one size on the rear tire as that is where the speedo take off is. So when we go to a 170/80 15 from a 160/80 15 we make our speedo error change from about 7% off to about 1% off. This is due to the new tire being taller than the old.

The percentage off does not change with speed.

If you are going 100 the speedo will say 107.

If you are going 60 the speedo will say 65.

If you are going 28 the speedo will say 30.


Speedometer error is a percentage thing.

The faster the more off it is.
 
#25 ·
speedo error and mpg

Another thing is when people tell you what kind of gas mileage they get you have to reduce that number by 5 to 10 percent because usually they just read the odometer which is also off the same as the speedo.

In my 750 aero my mpg corrected ranges from 47 to 62 depending.

Usually it's in the 53 to 56 range.
 
#26 ·
The odometers are off too?:mad: THAT, makes me very mad. I thought I done read somewhere that them odometers read seperatly from the speedo, as although they's hooked up by the same gears and such, it may be irrelivent to the numbers on the speedo? Don't know but that does piss me off, so what I can take 10% off the miles on my bike I guess?


chicago good thought, but it looked pretty stock to me, like a faimly sedan, an average person a drivin.

Man its so bad, I's almost hoping its only 5 MPH off!:shock: I mean I done road past one of them radar signs by a school, it be saying at 35 MPH on my speedo, actual speed is 30 MPH! So that would be slightly more than 10% off! It would be 31.5 MPH if it was 10% off.

That really just is not accetable to me. I wander if I can open up the speed and reright the correct numbers on it?:idea:
 
#34 ·
Vicious is dead on accurate as far as my GPS can get! I used a hall effect on the front wheel reading rotor bolts and fed a Speedo-Healer. The healer pulses a user defined percentage over the pulses received and transmits that to the Harley computer. The computer translates it to a serial databus that feeds the speedo. Took about 4 gas stops on my first trip after setting this up to get it **** on accurate!

Gonz
 
#41 ·
Gonz

I have no idea what any of the above means. :wink: Pass the Dilithium Crystals and energise for I have many Bleems to travel to get to my home planet.

Nanu Nanu and set Phasers to stun :-D

Collector (Dumbass - still in active service)