How many RPMs with stock rear diff?

[Jdk203]

I wanna try and switch out the gears in my bike to lower my RPM's on the highway but I'm nott 100% sure mine is stock. I was wondering if someone could tell me what kind of RPM's your running in 5th gear say at 50mph, 65, 70 somewhere in there.

 

[one2dmax]

Don't remember but I will note that tire size will have an effect on it too so anyone replying needs to let him know that.

You could try and watch the u-joint/driveshaft turning through the rubber boot area and turn the rear wheel over.

VMAX is 3.66 ratio vs Venture 3.33

Sean

 

[Jayhawk]

50 mph (indicated), 5th gear, is pretty close to 3,000 rpm, IIRC.

 

[Nicki66]

I just took note of my rpm's today, as I will be changing my final drive in the future.

60= 3900 rpm
70= 4600 rpm
80= 5200 rpm
90= 5900 rpm

These are in 5th gear with stock final drive.

 

[gamorg02]

what size front tire?

 

[one2dmax]

Both tires effect the outcome he is asking for. he wants the speed (front tire effects this) and RPM (rear tire/wheel size, final drive gear, and final trans gear) all effect this (not counting clutch slippage).

Sean

 

[gamorg02]

excellent point.

 

[satariel666]

I just took note of my rpm's today, as I will be changing my final drive in the future.

60= 3900 rpm
70= 4600 rpm
80= 5200 rpm
90= 5900 rpm

These are in 5th gear with stock final drive.

According to my calculations it should be like this:
60=3695
70=4311
80=4927
90=5543

Propably you have non stock front tyre size and speedo is not perfect.

EU versions have changed final drive so i guees its not possible that you may have diffrent ratio.

 

[satariel666]

Both tires effect the outcome he is asking for. he wants the speed (front tire effects this) and RPM (rear tire/wheel size, final drive gear, and final trans gear) all effect this (not counting clutch slippage).

Sean

And thats why im running with electronic speedo.
I can set exactly the tire circut with 1mm tolerance.
Very cool mod.

 

[Nicki66]

I'm running stock tire sizes.

Front 110/90-18
Rear 150/90-15

As far as speedo error, that is beyond my control. It is what Yami made it.

 

[satariel666]

I'm running stock tire sizes.

Front 110/90-18
Rear 150/90-15

As far as speedo error, that is beyond my control. It is what Yami made it.

Mechanical speedos are what they are.

Personaly i like a stock speedo a lot and wont change it but its a little dificult to match him with completly diffrent forks and wheel :confused2:

 

[Jdk203]

I just took note of my rpm's today, as I will be changing my final drive in the future.

60= 3900 rpm
70= 4600 rpm
80= 5200 rpm
90= 5900 rpm

These are in 5th gear with stock final drive.

I'm running stock tire sizes.

Front 110/90-18
Rear 150/90-15

As far as speedo error, that is beyond my control. It is what Yami made it.

Cool exactly what I was after. Ill check the tire sizes tomorrow but this gives me the ballpark I was looking for. I think my bikes running slightly higher rpms than yours but Id attribute that to tire size. I just really feel like shes screaming at 70Mph wanted to make sure everything seemed stock. Thank you

 

[gamorg02]

oh yea def screams at stock. esp with vboost wide fucking open!

 

[naughtyG]

I run a 110/90 - 18 Shinko at the front, and I think my speedo's generally a little optimistic.

With the Venture pumpkin, in fifth gear I get:

3000 rpm = 55 mph
4500 rpm = 65 mph
4000 rpm = 75 mph
4500 rpm = 85 mph
5000 rpm = 95 mph
5500 rpm = 105mph
6000 rpm = 115 mph

and so on - each 500 rpm gives another 10 mph.

 

[Nicki66]

Wow that's a huge difference between your 6k and mine. At 5900 rpm's I was doing 90, and your doing 115

 

[Nicki66]

I just took note of my rpm's today, as I will be changing my final drive in the future.

60= 3900 rpm
70= 4600 rpm
80= 5200 rpm
90= 5900 rpm

These are in 5th gear with stock final drive.

Okay I finally swapped out my final drive with a Venture drive unit.
stock tire sizes 110/90-18, 150/90-15

60 mph= 3500 rpm
70 mph= 4200 rpm
80 mph= 4700 rpm
90 mph= 5400 rpm

I is nice riding around at 60 and having the lower R's

 

[davesax36]

Sean (or anyone), could you post a chart (or point towards one) for your OD 5th with stock tire sizes and stock final drive? That is the comparison that's going to help me make this decision. Thanks

 

[one2dmax]

With the overdrive fifth Approx:

60mph = 3000
70mph = 3500
80mph = 4000
90mph = 4500

Maybe one of my customers on here can verify what they are getting and the tire sizes being run.

Rear Diff Ratios:
Venture is a 10% reduction (3.66 vmax rear ratio vs 3.33 venture rear ratio)

Overdrive/Stock Fifth gear ratios
Vmax 26/28 = .928
RS Overdrive 21/28 = .750

Not sure if the excell sheet attaced correctly and it's been a long time since I verified that the calculations put in there are correct.

Sean

 

[El Canadiense]

I do not understand how the rear wheel tire size or rim size affects the speedometer if the front tire size is the same as stock. (I know there is always some error in motorcycle speedometers). When I was in grade school, we had to measure the school yard with a wheel that was one yard in circumference and had a clicker on it. You only had to count the clicks to know the distance covered. It would not matter how fast you walked or ran, the distance would be the same. Why is that principal changing on a motorcycle if the speedometer cable is connected to a stock size front tire? Thanks.

 

[El Canadiense]

I am running a 170/80-15 on the rear and a 110/90-18 on the front. My tach is showing almost 5,000 at 110kph or 70mph.