My speedo reads ~10kph slow

[SamuraiMark]

On a long distance moto trip with some friends. After leading the pack for a bit everyone was asking me why I was going so fast. My speedo was reading 100-105kph, 107-112kph when passing. Turns out my speedo is out to lunch. When my buddie's speedo says 100kph, mine says 90. When mine says 103, he says he's at 110.

I've seen other threads indicating manufacturers set speedos in the other direction (reads 100kph, you're actually doing less). Anyone else seen this?

Running non-stock sprokets: 17T up front and 44T in the back.

- Mark

 

[ShoopCE]

Mark,

Your sprocket changes would cause the speedo to read lower, versus actual speed, compared to the stock config, which reads about 5% high.

Many people who've changed the front from the stock 16 to 17 report that the speedo is then pretty close to accurate. But you also took the rear down by 2 teeth which also reduces indicated speed versus stock, but by a smaller amount than the 1-tooth change at the front. So, you're probably reading a few percentage points low, not 10%.

I would guess your friend's speedo is probably reading a bit high.

http://www.600riders.com/forum/fz6-technical/53604-how-many-teeth-rear-sprocket-fazer-s2.html

Please search the forum for similar threads. A recent one showed expected speedo errors based on sprokect ratios.

I bought a SpeeodDRD because my speedo read 4.5% high and that really bothered me.:Flash:

Chris

 

[TownsendsFJR1300]

+1^^^^

Pick up a Speedohealer (or other device) and check your indicated speed vs actual with a GPS. Adjust the Speedohealer accordingly.

I have mine adjusted to within approx .3, .4 MPH.

 

[7UPyours]

does the speedo reading higher or lower effect how many miles are put on the bike? is the speedo being read by how fast the wheels are spinning?

 

[FinalImpact]

does the speedo reading higher or lower effect how many miles are put on the bike? is the speedo being read by how fast the wheels are spinning?

^^ Yes. They are linked and the ECM makes the calculation based on the output shaft speed from the transmission. Hence, changing the front or rear sprocket changes the distance the bike travels but the ECM doesn't detect the change.

At 5000 RPM in 6th gear:
16/46 = ~60.6 MPH, 1.01 miles traveled (( OEM ))
15/46 = ~56.8 MPH, 0.94 miles traveled
17/46 = ~64.4 MPH, 1.07 miles traveled

17/44 = ~67.3 MPH, 1.12 miles traveled **
16/48 = ~58.1 MPH, 0.97 miles traveled

** Can't imagine bike makes enough torque to pull this ratio. What is your MPG?

 

[04fizzer]

does the speedo reading higher or lower effect how many miles are put on the bike? is the speedo being read by how fast the wheels are spinning?

In stock configuration, the speedometer typically reads high (8-10% I've seen reported) while the odometer is accurate. Adjusting the speedometer with a speedohealer to read accurately will throw off the odometer.

 

[FinalImpact]

In stock configuration, the speedometer typically reads high (8-10% I've seen reported) while the odometer is accurate. Adjusting the speedometer with a speedohealer to read accurately will throw off the odometer.

Although S1 and S2's have a different cluster, my 08 S2 is pretty darn close. A section of freeway here has a defined mile marker interval for ODO checking over 5 miles. A mile a minute is 60 mph. 08 S2 is within 2% on BT023 rear and stock gearing.

TIRE ROLL OUT DISTANCE MATTERS!!! I do have to wonder if different years have different firmware in the ECM/CLUSTER to correct errors. Although it only show 1 PN for the either, that doesn't mean the production parts are THE SAME every year.


At 5000 RPM in 6th gear:
16/46 = ~60.6 MPH, 1.01 miles traveled (( OEM ))
So ride for 60 Seconds @ 60 mph = 1 mile

 

[TownsendsFJR1300]

As your tire wears, it'll slightly affect the speedometer as well.

With my speedometer dead on, the odometer is off very, very slightly as I'll compare to my GPS.

With stock gearing, and the speedometer adjusted to be accurate, the odometer will in the end, read slightly low..

I'd rather have an accurate speedometer than an odometer.

 

[SamuraiMark]

17/44 = ~67.3 MPH, 1.12 miles traveled **

** Can't imagine bike makes enough torque to pull this ratio. What is your MPG?

Not sure if this was directed at me. I get about 400km on a tank if there's not significant headwind. Well, I get 25 - 27km per litre. I've never run it dry to test it. It seems to pull just fine. Me + gear is over 200lbs + saddlebags, tail bag and tank bag and it still goes like hell. No problem cruising at 110 - 130kph and no problem passing other vehicles.

- Mark

 

[SamuraiMark]

Thanks all for the feedback. On the trip home I'll do some testing against mile markers to get a better handle on my target highway speed. It looks like 103 on my speedo is ~110 but I'll need to confirm. I should have realized the sprocket changes were going to have an impact.

Cheers,
Mark

 

[TownsendsFJR1300]

Thanks all for the feedback. On the trip home I'll do some testing against mile markers to get a better handle on my target highway speed. It looks like 103 on my speedo is ~110 but I'll need to confirm. I should have realized the sprocket changes were going to have an impact.

Cheers,
Mark

If you can borrow a car GPS, attach it to the bike (maybe near the speedometer) and read it and compare while your underway instead of guessing. (mine is a automotive GPS)

Most have battery power as well..

Also, it takes a steady hand on the throttle as the GPS is a bit slower to show actual speed vs what the speedometer shows immediatly...

 

[iviyth0s]

Not sure if this was directed at me. I get about 400km on a tank if there's not significant headwind. Well, I get 25 - 27km per litre. I've never run it dry to test it. It seems to pull just fine. Me + gear is over 200lbs + saddlebags, tail bag and tank bag and it still goes like hell. No problem cruising at 110 - 130kph and no problem passing other vehicles.

- Mark

If that's true then you get godly fuel consumption but I need more instruments confirming your odometer is reading correctly...

 

[SamuraiMark]

If that's true then you get godly fuel consumption but I need more instruments confirming your odometer is reading correctly...

It's been a while since I did a fuel mileage test but the last few times I did test it I was getting 25 - 27km / litre based on kms vs. fuel added. But to clarify, that is highway mileage at reasonable cruising speeds (110kph). I haven't paid it much mind since those last tests because my arse usually throws in the towel before the tank runs dry.

I know my odo is under. I am about 1KM short for every 10 kms of distances. I just did about 100km between two points on my current tour and the trip meter measures just over 90km.