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Discussion Starter · #1 ·
Since I compared the speedometer with a GPS based one, we are at about 7% off. 100 kmh speed in the dash = 93 kmh gps. So I decided to match the sprocket to the true speed by taking 2 teeth off.

Ordered a JT rear steel sprocket, JTR486.41 If you look up on their website they will work for R3. Dunno about the weight compare to our sunstar one but I will weight it when I get it. Taking 2 teeth off = makes speedo overread 1% higher which is good enough for me.
 

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Very Accurate!

My speedo is dead on from the factory.

See post #9
http://www.r3-forums.com/forum/554-...e-speedo-off-any-way-calibrate.html#post78721


"Just verified my R3 speedo on the way to work via my Garmin. Completely stock - I am no more than 1 MPH off at any given speed/gear. Most of the time I was within .5 MPH.


Speedo Read 25 - Garmin flickered between 24 & 25
Speedo Read 45 - Garmin flickered between 44 & 45
Speedo Read 50 - Garmin flickered between 49 & 50
Speedo Read 70 - Garmin flickered between 69 & 70


This is the most accurate speedo I have ever seen from the factory."


Good luck with yours!
 

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I just installed a Ram mount on my R3 so now I have my Garmin Nuvi 3500 with me everywhere I go.
My speedometer reading at 60mph on the R3 is reading 59mph on the Garmin.
Great solution though if you are reading that much off.
 

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Discussion Starter · #5 · (Edited)
+1t on the Front sprocket should be an easier and cheaper solution.
Unfortunately they don't offer +1 tooth front, only -1 2 3.



So based on all info we gathered here, I think the US R3 has accurate speedo, Canadia, Euro, Australian market speedo are off.
 

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Unfortunately they don't offer +1 tooth front, only -1 2 3.



So based on all info we gathered here, I think the US R3 has accurate speedo, Canadia, Euro, Australian market speedo are off.
Here's one available in 15 tooth. It is for a 520 chain, which is the stock R3 chain (520VF). They also offer a 16T.
http://www.afamdrive.com/sprockets-chain-kits/yamaha/street/yzf-r3-2015/

This will change speedometer readings...

The 14T fits without interference in the case and without a need to add links to the chain. Just move the wheel forward slightly. Going 3+ teeth smaller on the rear will require removing links. Plus, quality rear sprockets are typically 2x as expensive (or more) than front sprockets.
 

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+1T front sprocket?

+1t on the Front sprocket should be an easier and cheaper solution.
Has anyone done this yet?

I'm also finding first gear is too low even for hill starts from a dead stop, and find I mainly use second gear...+1T on Front would also help in high gear and cruise speed I imagine as well as fuel mileage

Feedback would be great..
 

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Someone knows a 13T front sprocket for sale? European market sux, even my local dealer can't help me out.
 

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So if I go -1 front, +3 rear how much will that screw up my US speedometer?
OEM gearing is 43/14 = 3.07

If you go -1 front and +3 rear, that will become 46/13 = 3.54

So the new gearing is 3.54/3.07 = 1.153 what the old gearing was. (i.e. 15.3% numerically higher)

That will make your speedometer read 1.153 times as high as it did AT ANY GIVEN SPEED than it did before, but the "before" was incorrect to begin with, right?

So, it will read 1.153 times what it did before, but you now have to correct that false reading to reflect your ORIGINAL speedo error.

So, FOR EXAMPLE ONLY, if your original speed error was that it read 1.07 times the real speed (i.e. it read 7% higher than reality, then it would now read 1.153 x1.07 = 1.23 of actual speed (23% too high).

It's a brain twister, especially if the original and the modded are off in opposite directions. In those cases, it is easy to do the math ratios "backwards" and be wrong. I did this as a small business for a while years ago, and the math can suck. Don't ask me to do another example. :)

By the way, with the 46/13 gearing, your engine rpm at a TRUE (not indicated) 60 mph would be about 7000 rpm.

Jim G
 

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OEM gearing is 43/14 = 3.07

If you go -1 front and +3 rear, that will become 46/13 = 3.54

So the new gearing is 3.54/3.07 = 1.153 what the old gearing was. (i.e. 15.3% numerically higher)

That will make your speedometer read 1.153 times as high as it did AT ANY GIVEN SPEED than it did before, but the "before" was incorrect to begin with, right?

So, it will read 1.153 times what it did before, but you now have to correct that false reading to reflect your ORIGINAL speedo error.

So, FOR EXAMPLE ONLY, if your original speed error was that it read 1.07 times the real speed (i.e. it read 7% higher than reality, then it would now read 1.153 x1.07 = 1.23 of actual speed (23% too high).

It's a brain twister, especially if the original and the modded are off in opposite directions. In those cases, it is easy to do the math ratios "backwards" and be wrong. I did this as a small business for a while years ago, and the math can suck. Don't ask me to do another example. :)

By the way, with the 46/13 gearing, your engine rpm at a TRUE (not indicated) 60 mph would be about 7000 rpm.

Jim G

Jim, My speedo is actually right on currently. Maybe +\- 1mph. And I've also verified against GPS speed with my navigation app.
Would I be correct then to presume that it would make my speedometer read more like 16% high as opposed to the 23% you came to above?

Also, I am wondering how you came up with your 7k @ 60mph figure? I have attached a screen shot that shows a breakdown for that specific sprocket setup. Do the other numbers seem to be in line?
 

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Jim, My speedo is actually right on currently. Maybe +\- 1mph. And I've also verified against GPS speed with my navigation app.
Would I be correct then to presume that it would make my speedometer read more like 16% high as opposed to the 23% you came to above?

Also, I am wondering how you came up with your 7k @ 60mph figure? I have attached a screen shot that shows a breakdown for that specific sprocket setup. Do the other numbers seem to be in line?
Travis, if your speedo is (miraculously*) "right on" before any gearing change, than it will read 15.3% high after the gearing change to 46/13.

I don't have time to analyze someone else's very data packed chart, but can tell you the following which should make it easy for you to do your own checking:

- A Yamaha R3 with OEM gearing and OEM tire diameter spins its engine at approximately 6096 rpm at 60 mph

- This means that WITH OEM GEARING the formula to calculate engine rpm for ANY speed in 6th gear is:
Speed divided by 60 x 6096 = engine rpm at that speed

WITH OEM GEARING, If you need to calculate engine rpm in any other gear at any specific speed:

In 1st gear: Speed divided by 38 x 12066 = engine rpm at that speed

In 2nd gear: Speed divided by 52 x 12043 = engine rpm

In 3rd gear: Speed divided by 67 x 11469 = engine rpm

In 4th gear: Speed divided by 82 x 11320 = engine rpm

In 5th gear: Speed divided by 97 x 11334 = engine rpm

With your proposed 46/13 gearing, just multiply any of the above results by 1.153 to get the "new" rpm.

* GPS indicated speed is NOT exactly correct at all speeds. In fact, it can be significantly off for technical reasons that I have seen discussed before, but cannot recall where, and I don't care about GPS speed accuracy because I personally don't use GPS to measure my speed, so I haven't paid attention to the technical discussions. I think at least one of the technical discussions was on a thread on this forum so you can look for it if you want.


Jim G
 

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Good information, Jim. I appreciate your responses.

I did see the GPS discussion that occurred on this forum as well. I understand that it’s not the end-all be-all for speed calculation.

Again, thanks for the detailed responses. It’s great information!

Shiny side up!


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