I've read just about everything published, and I'm seeing quite a difference in the top speed of the Stook. Anywhere from 162/157 to 143/140/.

Does anyone know for sure,,, or does it vary that much from stook to stook?

dave (S/B in just a few short weeks)

 

A friend of mine has gotten the following numbers consistently on two or three runs: 153 top up, 143 top down. The runs were made on a flat surface in the Southern California desert. Elevation is probably a few thousand feet.

 

I got 150 MPH Top up

 

I wouldn't trust the speedo very much at those speeds. Try measuring top speed with a GPS which is very accurate. Most speedo's are at least 5%-10% high on the upper end of the scale.

 

pfb.

Accuracy varying by speed is an analog speedo 'feature'. It is unlikely to be an issue on a digital speedometer.

Furthermore, in my experience, analog speedos generally under-report as things get faster.

Dan.

 

Not my experience.

The S2K speedo is definitely optimisticwhen measured against my GPS. At 123 MPH GPS measured, the digital speedo was showing higher. Can not remember how much.

All my analog speedo's on my motorcycles and other vehicles are also optimistic. They "over-report", not "under-report".

 

Enough reports have come in to be sure the speedometer reads at least 1% fast and more commonly close to 4% fast. I think that puts most actual top speeds in the 143 to 156 range.

 

Can't speed be interpolated from the tach reading, which should be accurate.

 

Yes,

take final rmp

9000 for example and divide by the final drive ratio. 6th gear and rear end gear

Then multiply that number by the size of the tire measure in feet.

Take that number and divide by 5280
and then multiply that by 60mph

9000/final gear ration= A

A*tire size = B

B/5280 = C

C*60mph = D( or a big ticket)

 

Using the above method I was able to calculate speeds on many of the vehicals to which I changes tire size, rear end gear, transmission, or sproket specs. The more exact your measurements the closer to acurate it will be. I was able to get within a few mph in most cases. This helps alot when your speedometer reads 60 and your are really doing 80 or when your speedo is pegged out on an old anolog speedo. (my chevelle for example)