Speedometer Accuracy

[ShoopCE]

For those of you with speedometer correction devices, what number do you use to make it read accurately? (With stock sprockets: 16/42)

I've loved my FZ6 since I bought it last fall, but I was horrified to learn that when I thought I was sticking to the speed limit I was actually going 5 mph or more below it. I guess being an analytical chemist makes it difficult to handle knowing your speedometer is so far from being accurate. That and being passed by grannies.

So I did some research here and in other forums and decided to buy a SpeedoDRD. After COMPLETELY blowing my wife's patience for "just one more time" I settled on a factor of -4.5%. The correction is linear, at least from 40 to 70 mph. But I've read posts where some claim the correction is 10% and that it varies across the range. So I thought this sounded like an interesting poll. Though the acctual correction is a negative number, I've listed them as positive.

Chris

 

[Gary in NJ]

Most motorcycle speedometers are optimistic by 5 to 10%. BMW's are even higher.

 

[major tom]

The problem is once you correct the MPH now your ODO will be off. I observed mile marker signs and compared my trip meter. They were very close, completely acceptable. I went up one tooth on the CS sprocket and now my MPH is absolutely spot on, but my ODO reads 3.8% low. So if I want to determine my true fuel mileage I have to multiply by .96 each fill up. Frustrating. I do absolutely love the more relaxed engine feel now though. Oh well, sometimes you can't have it all.

 

[Cortez]

For those of you with speedometer correction devices, what number do you use to make it read accurately? (With stock sprockets: 16/42)

I've loved my FZ6 since I bought it last fall, but I was horrified to learn that when I thought I was sticking to the speed limit I was actually going 5 mph or more below it. I guess being an analytical chemist makes it difficult to handle knowing your speedometer is so far from being accurate. That and being passed by grannies.

So I did some research here and in other forums and decided to buy a SpeedoDRD. After COMPLETELY blowing my wife's patience for "just one more time" I settled on a factor of -4.5%. The correction is linear, at least from 40 to 70 mph. But I've read posts where some claim the correction is 10% and that it varies across the range. So I thought this sounded like an interesting poll. Though the acctual correction is a negative number, I've listed them as positive.

Chris

It's the same on all bikes and cars, give or take a few %.

I just check the speedo error at 40, 60, and 80mph at local radar traps
and adjust my riding. Costs nothing.

Also, most bikes get the speedo spot-on with +1 front sprocket, but your
rear isn't stock either so.. yeah. And your ODO is now showing incorrectly
too, which is something I'd me more worried about then the speedo.

 

[MattR302]

I tested my old EX500 and my ZX6R with a GPS. The EX500 speedometer is picked up off the front wheel, the ZX6R off the driveshaft.
On both of them:
65mph indicated = 62mph actual
80mph indicated = 75mph actual

That being said, I don't worry about speedometer error. Heck, on my DR350 the speedometer only works up until 45mph or so, then it just stays there.

 

[TownsendsFJR1300]

I installed a Speedohealer and adjusted it, not with their chart, but off my GPS.

It is within .2 MPH (yes, .2) at 60 MPH

An off odometer won't get you a speeding ticket. An OFF speedometer CAN..

 

[Fishwiz4]

As long as the odometer is reading lower than actual miles, that's a good thing, right?

Sent from my DROID RAZR HD using Tapatalk

 

[TownsendsFJR1300]

As long as the odometer is reading lower than actual miles, that's a good thing, right?

Sent from my DROID RAZR HD using Tapatalk

I'd rather have the odometer read low than high. Better for re-sale later as would an accurate speedometer...

If running a "timed/mileage event", most guys use a GPS so you could get your accuracy from that which should be dead on...

 

[Fishwiz4]

I'd rather have the odometer read low than high. Better for re-sale later as would an accurate speedometer...

If running a "timed/mileage event", most guys use a GPS so you could get your accuracy from that which should be dead on...

When selling a vehicle though, you have to provide the true mileage, or sign a document that says the odometer is true to the best of your knowledge. Sorry to get off topic though.

Sent from my DROID RAZR HD using Tapatalk

 

[FZSexy]

at 50mph gps as well as those road side radar "speed readers" say i am going 48mph. i figure 100mph would see me at 96mph, so i chose 4%

 

[TownsendsFJR1300]

When selling a vehicle though, you have to provide the true mileage, or sign a document that says the odometer is true to the best of your knowledge. Sorry to get off topic though.

Sent from my DROID RAZR HD using Tapatalk

Its your choice. I know down here, you simply put the mileage from the odometer on the title when selling it.

If your concerned about it, write down the mileage when you correct the speedometer (Speedohealer/front sprocket).

When you sell the bike, you add 4% (of whatever the # off it is) of the current shown mileage for the TRUE MILEAGE of the bike....

Note: Your adding 4% to the corrected mileage, NOT the overall odometer reading..

 

[TownsendsFJR1300]

at 50mph gps as well as those road side radar "speed readers" say i am going 48mph. i figure 100mph would see me at 96mph, so i chose 4%

That is EXACTLY how mine was before the Speedohealer.

Now at 4,000 RPM's, its exactly 48 MPH (it did use to read 50 MPH)

 

[FinalImpact]

As best I can tell the 08 S2 is more accurate than the same 07 version and all S1s. That said, it should have a different part number but this value may be derived from the ECM and NOT the speedo. Hence, those looking for a PN change may not find it.


That said: 08 - 09 US owners; how accurate is your speedo?

 

[FinalImpact]

That is EXACTLY how mine was before the Speedohealer.

Now at 4,000 RPM's, its exactly 48 MPH (it did use to read 50 MPH)

A thread from the past on this topic: Read This! RPM, Gear, Sprockets, Tire = Actual Speed! http://www.600riders.com/forum/fz6-...tire-actual-speed.html?highlight=ratio,+speed


Scott,
Math came out close to your number. Considering tires vary in size this comes in pretty close using all the facts as listed by the manufactures.

Specifically your 4000 RPM statement vs Gps. Here is what I calculated!

RPM: -- Gear: - MPH: - Miles traveled 60 Sec
4000, - 1, - 18.5, - 0.308
4000, - 2, - 27.0, - 0.449
4000, - 3, - 33.7, - 0.562
4000, - 4, - 39.4, - 0.657
4000, - 5, - 44.1, - 0.735
4000, - 6, - 48.5, - 0.808

A 180/55/17 = tire calculates to a rolling distance of 77.9" or a diameter of 24.8"
Your real world gps value at 48 MPH indicates the tires diameter as 24.56" with a rolling distance of 77.15"

In short we are talking about a difference of 0.25" (total diameter difference from calculated), taking into account the variations in tire design, tread, pressure, temperature, etc, that's pretty darn close in my book. Now if we just knew how accurate the tach is??!!!

 

[FZSexy]

That is EXACTLY how mine was before the Speedohealer.

Now at 4,000 RPM's, its exactly 48 MPH (it did use to read 50 MPH)

interesting as my bike is a 2007, as well

hmm...:eyebrow:

 

[TownsendsFJR1300]

I didn't use the table Speedohealer provides, just fine tuned it per the GPS.

Trying to hold the throttle steady for the GPS to catch up, then take note of the speedometer and adjust.

When you get to the point you not sure to adjust up or down, your there...

As noted by Randy' post and my earlier post, the speedometer is now within .2-.3 TRUE MPH with NO GPS lag..