How off is the Stock speedometer and what have I done with a 16T front?

I just installed a 16T front sprocket on my 2007 FZ1 and I knew it would mess with the speedometer but WOW! My question is, how off is the speedometer with the STOCK gearing? That I do not know. When I change the front sprocket one tooth, the math tells me the speedometer will read 6.25% higher. So how much more is it off from the factory since I need to also add that in.
 
Wow. Add that to the 6.25% from changing from a 17 to a 16 front and that’s 12.25%. That’s a lot. Now I know when my speedo said I was doing 80 everyone was passing me in a 70 zone.

I think I am going to get one of those speedo healer things.
 
Wow. Add that to the 6.25% from changing from a 17 to a 16 front and that’s 12.25%. That’s a lot. Now I know when my speedo said I was doing 80 everyone was passing me in a 70 zone.

I think I am going to get one of those speedo healer things.
going from 17 to 16 is 6.25%...That is it. Not sure where you got the other 6%?
 
going from 17 to 16 is 6.25%...That is it. Not sure where you got the other 6%?
I may have misread greeno’s post thinking he meant the stock was off 6%. I guess it isn’t but stock, Yamaha has it off some amount. That amount, whatever it is, would need to be added to the 6.25%. No need to mince the numbers, but wow was it off. I used the Healtech speedo healer and it has fixed everything up very nicely.

BTW, do you know how much the stock settings are off on the speedo?
 
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fwiw, do a gps test or find one of those speed scan signs and do your own tests.
I find my 2013 FZ1 is ~7% off (stock gearing).

44 indicated = 41 speed sign
85 indicated = 79 gps.

I had an 07 FZ6 with pretty similar speedo discrepancy.
 
I've changed my sprockets with 16T/46T and I fixed with speedohealer. Now my discrepancy is 1 miles ahead of the real speed.
I have a second speedohealer to sell tho, bought by mistake
 
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Thought I'd add my 2 cents for others that may still be looking at this question... calculating how far off percentage wise, I don't see where it's very useful (to me), I just want to know how fast I'm going, so I have a holder on my handlebar where I mount an older iphone and I run the Speed Pro+ app by Mother Tucker LLC. It uses a GPS to track my speed and I use that to verify my actual speed. Stock, my odometer says 85 and the app says 80. After I stop I can save my "track" as they call it and it provides me with a map of where I started the app and where I ended along with exactly where on the map I hit my top speed and what the speed was for that track. It provides you with a Route Time, Avg Speed, Top Speed and Altitude and also your current location. I find it very useful, helping me with my current speed and bragging proof regarding my top speed.
 
Thought I'd add my 2 cents for others that may still be looking at this question... calculating how far off percentage wise, I don't see where it's very useful (to me), I just want to know how fast I'm going, so I have a holder on my handlebar where I mount an older iphone and I run the Speed Pro+ app by Mother Tucker LLC. It uses a GPS to track my speed and I use that to verify my actual speed. Stock, my odometer says 85 and the app says 80. After I stop I can save my "track" as they call it and it provides me with a map of where I started the app and where I ended along with exactly where on the map I hit my top speed and what the speed was for that track. It provides you with a Route Time, Avg Speed, Top Speed and Altitude and also your current location. I find it very useful, helping me with my current speed and bragging proof regarding my top speed.

Might be a dumb question, but does this "old" iphone have to be on a plan to still synch up with GPS / satellites?

I saw one in the closet last week I could bring back to life to check my bikes speed with.
 
When I bought my Gen 2 it had the std 17T and when I put on 190/55 the reading was bang on !

Now I'm running a 16T and at 60k's it reading 63/64 and 90k's 95/96

Few years back I has a Gen 1 with an Ivans kit and all it had a 15T and 1st gear was a weapon LOL
 
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