[amartin]

Okay, the subject is a little misleading.

But here's the situation: I bought my R1 with ~250miles on it about 1year ago...and I've left it stock.

After much reading about how many people top out 6th gear at ~186-188mph, I did a little math..

ASSUMING you guys are running 14,500 RPMs in 6th, I took that number divided by 3.. or ~4800 RPMs.

I then, in 6th gear, got up to 4800 rpms, and my speedo indicated 70mph.

Simple math says, that if I could pull 14,500 rpms in 6th, I'd be going 70*3 or 210mph.

Of course, I can't really run 210mph, so my question is:

Is my SPEEDO WAAAAYYYY off, or did the previous owner change the sproket?

Would a -1 in the front or +2/3 in the rear have about this amount of error? Because, from what I can tell, I'm 24mph off maxed out in 6th, inessence, reading 13% faster than everyone else that is stock (and we know we read faster than we are really going anyway).

Any input appreciated,
Aaron

 

[F16]

I think there are many more factors to consider like more drag at higher speeds and who know what else. It probably take more power to go faster as velocity increases.

 

[rdandy5875]

with -1 gearing your speed will be about 12% optomistic.

stock is about 6-7 optomistic%.

You should take off the sprocket cover and see what size sprocket is in there....

 

[IeatAPC]

Gear Ratioes are different. Thats what makes 3rd gear 3rd, and 6th gear 6th.. The Rpm's vs. MPH will not match up form gear to gear...

 

[rdandy5875]

Gear Ratioes are different. Thats what makes 3rd gear 3rd, and 6th gear 6th.. The Rpm's vs. MPH will not match up form gear to gear...

Th only thing I saw in the first thread is 6th gear. I think everyone knows what you said, or they should not be on a bike.

Although I do agree if you pull 4800 @70, then at 14,400 it would read 3x higher, minus some speed for drag and wind resistance.

You might be off by 12% at low speeds, But then check this out, at high speeds, your tire will expand and make the speedo more accurate :fact

 

[R1PLUS]

I am not a scientist or anything, so that said, there is a physical lock on the turning of the crank throught the transmission to the sprockets that is not affected by wind resistance. It may take more power to drive the machine but the simple math of 4800 X 3 should be pretty close.

The tire will stand taller at 180+ and that will effect speedo accuracy some. Other than that I can't explain why our spedometers are not accurate at higher speed though.

Then again, I could be so wrong it is pathetic.

I just wanted to post up.:bs

 

[amartin]

Okay..so, I just did a quick test-- @ 60mph in 6th gear, I'm running ~4050rpms. Anyone else that happens to be stock know what RPMs they are turning @60mph in 6th?

 

[nee.dragger]

Simple math says, that if I could pull 14,500 rpms in 6th, I'd be going 70*3 or 210mph.

Can you pull 14,500 rpms in 6th gear? I think not. Only if you had enough horsepower, which I doubt you do. At 70mph, your tach reads 4,800 rpms. But are you really going 70mph. Speedometer error says you are but you might really be going 66mph or less. Difference of 3 - 4 mph * 3 will equal 12 - 16 mph less in actual speed. So, at 14,500 your speedometer reads 210, you might really be going 194 - 198 mph, if you could get to 14,500 rpms.

Is my SPEEDO WAAAAYYYY off, or did the previous owner change the sproket?

Your speedometer can be as much as 5% off. But, your tachometer is not always accurate as well. It can also be as much as 5% off. If your tach reads 4,800 rpms at 70 mph, the engine might really be revving 4,560 rpms. Then you also have tire circumference. Rear tire size 190/50/17 may not have the same circumference for tire manufacturer A as with tire manufacturer B. They may be close, but a difference of 5 - 10 mm changes the final drive ratio by a lot. And then, as someone else posted, as speed increases, the rear tire expands, which creates its own speedometer error. The combination of both errors could give you very high mph readings. You hear of some guys on 600cc sportbikes saying their speedometer showed 185 mph, when in fact their max speed is only 165 (or thereabouts). That's due to all of the factors above.

 

[amartin]

Hence why I'm asking if anyone else could do a 60mph (or 70) run and note the RPMs in 6th and post them here... (on a stock bike)

 

[Sabian]

amartin...run to 6000 rpm and tell me what you read for mph. I have stock gearing , and I know I read 86/87 mph...it bounces between the two.

 

[nee.dragger]

Also, a smaller size rear tire give a high reading on the speedometer. Hence, with 60 mph indicated, a 180/5/17 tire on a bike geared for a 190/50/17 might really be going 55 mph instead of 60mph.

 

[madmathew]

I thought that you pushed it out the back of a C-130 or something.

 

[Southern118]

you also have to account for the clutch slippage at that and you ahve to break the wind barrier at some point and the rear tire will be spinning

 

[DadMan]

I have a -1/+2 setup and read 85 @ 7000 in 6th. I have verified this is correct with my gps. I use my gps often to keep my speedohealer correct. Any tire wear, etc. makes it get out of whack a bit. I verify the speedo every two weeks, because I don't want to look down and wonder how fast I am really going.

/DadMan

 

[Sharksawyer]

I have a -1/+2 setup and read 85 @ 7000 in 6th. I have verified this is correct with my gps. I use my gps often to keep my speedohealer correct. Any tire wear, etc. makes it get out of whack a bit. I verify the speedo every two weeks, because I don't want to look down and wonder how fast I am really going.

/DadMan

You check it every two weeks? Dude, the circumference difference between a new tire and an old tire is less than one percent. So if you're right at 60 mph at xxxx rpms with a new tire, then you'll be at 60.6 mhp with the same tire near the end of it's life. I set my Yellow Box exactly once and have never thought about it again, until now. As long as I'm within one mph, who cares if it's totally accurate. Me thinks I would spend more time enjoying the scenery or watching out for runaway Hummers than calibrating my Spedohealer to .0000000000001%.


Peace,

Mark
99 R1

 

[LDHR1]

my 05 cuts the fuel at 13,750 rpms, if you are getting 14,400 you are on an r6.

 

[aintgotabike]

my 05 cuts the fuel at 13,750 rpms

mine too..its stock

 

[matt_f_001]

my 05 cuts the fuel at 13,750 rpms, if you are getting 14,400 you are on an r6.

My 05 is completely stock and it pulled to 14,000 rpms in 6th gear. I had always assumed it would cut out but it kept going :dunno

 

[aintgotabike]

did you really have the balls to look down while going that fast? :scared

 

[fiveoh]

Why does everyone seem to think that drag (aero, friction, etc.) changes speedo error? Assuming the clutch and tire are not slipping it is fixed. Oh and we are definitely not going to spin the tire trying to overcome aerodynamic drag. :lol