Dyno Day, Shocking Results!!!

[Steve Carlton]

The R1200S only came to the US with a 2.75 final drive ratio.

[signit98]

Out of curiosity, folks... has anyone else topped into the rev-limiter in 6th? And, if so... did you manage to look at the speedo?

It's an odd thing... you top out.... the bike stutters and slows down a couple of MPH's and then works it's way into the limiter again... gives you plenty of time to look - if the straight you are on it long enough, that is!

[feds27]

Originally Posted by shreddr

.....120.7 RWHP!.....

That's it?

[AZ-J]

Sweet!

[zx9rmal]

Originally Posted by signit98

Out of curiosity, folks... has anyone else topped into the rev-limiter in 6th? And, if so... did you manage to look at the speedo?

It's an odd thing... you top out.... the bike stutters and slows down a couple of MPH's and then works it's way into the limiter again... gives you plenty of time to look - if the straight you are on it long enough, that is!

I did. Just over 160 mph indicated. It's easy. I don't look at the road much.

No way the R12S will do an ACTUAL 169 mph with standard (2.75) gearing and rev limit.

[signit98]

Thanks, Mal... Hmmmm there is a 3 to 5 mph difference between your reading and mine... I wonder whether there could be that much variance in speedometer readings from bike to bike.

But then, he had a GPS showing 169 and we went by speedo indication... and speedo's usually go a little fast...

[peter f]

My max (end of straight) : 245 km/h (GPS) > I think > ~153 mph

[shreddr]

I mistakenly posted that the speedo read lower than the GPS, it actually read higher. When the speed was saying 80, the GPS unit was saying 70. It would be understandable if these things aren't that accurate, given the slight amount of time spent at whatever speed I got up to. I think a magnetic wheel sensor would probably be more accurate. No matter, its way faster than I like to go. Like I mentioned here before, twisties and accelerating in 3rd and 4th gear is what its all about for me.

[roger albert]

Hmmmm there is a 3 to 5 mph difference between your reading and mine... I wonder whether there could be that much variance in speedometer readings from bike to bike.

Easily. And that's what, 1-2% difference? You can get a good deal more variance than that in tire circumference, due to AT LEAST 3 reasons.

Different amount of wear
Different sidewall height
Different diam from brand to brand
Differing growth at those speeds (and all tires grow at those speeds,
some dunlops, sometimes disasterously)

[signit98]

Between Peter's 154 and shreddrs 169, the would be more like 10%, Roger... basing on the low number... with mine being somewhere in between...

[feds27]

Now that we've settled the score on who's fastest on dry, how about showing numbers for top wet speed? What? No takers? Bunch of pansies.

[signit98]

That's unfair, I can't compete...

[roger albert]

Between Peter's 154 and shredrs 169, the would be more like 10%, Roger... basing on the low number... with mine being somewhere in between...

True, but I was only addressing the quoted 3-5mph difference.
In any event, speedos are off more than 5% all the time, and best and worst case rear wheel variance can, again, be much more than a couple percent. 10% difference just due to tire and speedometer quite possible (I've seen that from speedos alone, and not all that infrequently, though less often that severe with modern stuff). More when you add motor, tune, rider, and atmospheric factors. I don't see anything _necessarily_ inconsistent or unbelievable just yet. An actual 169 is EXTREMELY unlikely though. HP:Aero just not there.

[signit98]

Yeah... and I have learned not to trust my GPS either...

Last year it told me that there was a road and what I got was the Moki Dugway... tztztz

[EZ-RIDER]

Hook up a Sigma bike computer and set it to the proper wheel diameter then go for a ride and see what your Real Top Speed ! I found the BMW Speedometer is off by 1 % under 100 Mph above it is off by 5 %

[pmc847]

EZ,

I use the Sigma and I concur.

Ralf,

I was using a map (M D not on map) when Jane and I went to Utah. What a surprise when after riding 90 mph we came upon a sign that said blacktop ends, dirt road ahead slow to 10 mph. The view was amazing and the road down was more than exciting to do 2 up on the BCR.

Philip

[shreddr]

180 degree, downhill dirt switchbacks does not look like a place where an "S" bike would shine.

[signit98]

Jeff, the only thing that shines on the road, when riding an 11S BCR, is the white of your knuckles...

Cool road though...

Phillip, next stop... Shafer trail!

[ckcarr]

Crybabies!
I was just there Monday.


art...

[bacn5]

Originally Posted by roger albert

Easily. And that's what, 1-2% difference? You can get a good deal more variance than that in tire circumference, due to AT LEAST 3 reasons.

Different amount of wear
Different sidewall height
Different diam from brand to brand
Differing growth at those speeds (and all tires grow at those speeds,
some dunlops, sometimes disasterously)

Roger,
Just to clarify: They are comparing speedometer reading to speedometer reading on identically geared bikes. Since the speedometer is measuring the speed of the ring tone in the trans or final drive, both bikes should read the same in top gear at the rpm limiter unless:

The rev limiters are engaging at slightly different rpms
One of the two bikes clutches are slipping slightly under top end loads
The magnetic pick-up in one of the bikes has more metal shavings on it (most likely).

The tire diameter would effect the actual top speed of the two bikes at the rev limiter but not the indicated speed at the speedo.