2008 Speedo Error

[SouthernCruizer]

So...I finally got round to installing my Zumo on the new black beauty...take her for a spin, and damnnnnn...at 70mph indicated, GPS shows only 65!! My '04 FJR gps'd at 67mph for the 70 indicated. I think 5 mph error at 70 is ridiculous. I was so happy that the rpm had dropped so much from the '04 to the '08, and now I see it's a false drop, since the speedo error is increased! :angry:

 

[Silent]

So...I finally got round to installing my Zumo on the new black beauty...take her for a spin, and damnnnnn...at 70mph indicated, GPS shows only 65!! My '04 FJR gps'd at 67mph for the 70 indicated. I think 5 mph error at 70 is ridiculous. I was so happy that the rpm had dropped so much from the '04 to the '08, and now I see it's a false drop, since the speedo error is increased! :angry:

5-10% spedo error is about normal across the board for motorcycles.

 

[radman]

Pretty soon they're just gonna quit answerin' the phone at Cypress........... B)

 

[Ignacio]

So...I finally got round to installing my Zumo on the new black beauty...take her for a spin, and damnnnnn...at 70mph indicated, GPS shows only 65!! My '04 FJR gps'd at 67mph for the 70 indicated. I think 5 mph error at 70 is ridiculous.

The speedo inaccuracy change from Gen 1 to Gen 2 is old news. Gen 1 is usually closer to 2% and Gen 2 closer to 5%.

I was so happy that the rpm had dropped so much from the '04 to the '08, and now I see it's a false drop, since the speedo error is increased! :angry:

Regardless of your observation there is, in fact, a gear ratio change between generations that even after speedo differences are adjusted for...the Gen 2 is running lower RPMs for the same absolute speed. IIRC, it was about 3,000 rpm at 70 mph or so.

I'm trying to find the comparisons and make sure they're added to the Bins O' Facts....but can't find Gen 1 yet.

 

[radman]

GenI is 4100 at 70mph. If that indeed was what you were looking for. I believe GenII is 3700 at 70 IIRC.

 

[Ignacio]

GenI is 4100 at 70mph. If that indeed was what you were looking for. I believe GenII is 3700 at 70 IIRC.

Actually, i think I goofed. I think it's 300 rpm less.....so 3,800 RPM or so for Gen 2 at 70....or your 3,700 rpm makes sense too.

 

[motorcycle-ed]

This is an interesting thread. I did not know about this difference. If this 3700 vs 4100 is true that is a BIG difference. I wonder what they changed??? Transmission gears...rear drive gears...?

Ed

 

[FJR@DTS]

So....I'm only breaking the law 5 miles per hour less than I thought?

 

[Constant Mesh]

Yamaha used a magician's trick on the '06 and later. They tweaked the MPH software and made the speedo read very high.

This gave the impression that the small gearing change in the '06 had a much bigger effect than actual.

The engine speed on the '06 only slowed 2.7% compared to earlier models.

'05 4K rpm = '06 3892 rpm

Only 108 rpm reduction.

But pair this with a more optimistic speedo and it appears the gearing change was quite dramatic when of course it was a very minor change.

 

[charismaticmegafauna]

I wonder what they changed??? Transmission gears...rear drive gears...?

Intermediate gears -- the right angle, 90* gearset that drives the shaft (where the front sprocket would be, if chain drive).

 

[Ignacio]

The engine speed on the '06 only slowed 2.7% compared to earlier models.

You remember where that was documented?

 

[Constant Mesh]

It's easy to calculate.

They changed one gear on the transmission's output shaft. The new gear on the '06 has 37 teeth. The '05 gear had 36 teeth.

36/37 = 0.973

'06 rpm = '05 rpm x 0.973

 

[SouthernCruizer]

A couple of you got my point. I thought the RPM drop at highway speed was more significant than it now appears to be. I am glad the higher gearing is on my '08, but the difference is not as high as I had hoped once the GPS verified the error %. Regardless, the '08 is definitely smoother than my '04 was.

 

[Ignacio]

It's easy to calculate.
They changed one gear on the transmission's output shaft. The new gear on the '06 has 37 teeth. The '05 gear had 36 teeth.

36/37 = 0.973

'06 rpm = '05 rpm x 0.973

That helps, but to confirm is that 36-37 change part of the the secondary reduction gear?

If so, then I have 2.773 (35/36 x 21/27 x 33/9) from the Gen 1 service manual.

Would Gen 2 then be 2.698 (35/37 x 21/27 x 33/9)?

 

[Constant Mesh]

Yes, you have it right. If you look at an '06 or later Owner's Manual the 2.698 that you calculated is shown in the Specifications section of the manual.

 

[Ignacio]

Yes, you have it right. If you look at an '06 or later Owner's Manual the 2.698 that you calculated is shown in the Specifications section of the manual.

Thanks, I'm going to add this to the respective FAQs. It's the kind of data we don't refer to that often, but nice to have it.

 

[2WheelTiger]

A couple of you got my point. I thought the RPM drop at highway speed was more significant than it now appears to be. I am glad the higher gearing is on my '08, but the difference is not as high as I had hoped once the GPS verified the error %. Regardless, the '08 is definitely smoother than my '04 was.

Buy a taller rear tire. Yes, there are differences even when the sizes claim to be the same.