'92 VR - RPMs on Highway

Just curious how fast the motor should be running @85mph in 5th gear.

Just got my bike on the highway for the first time and it turns 4000rpm @ 85 in 5th.

That seems a little high to me, but then again, this is the first time I've ridden a Venture at highway speeds.

Just curious how fast the motor should be running @85mph in 5th gear.

 

Just got my bike on the highway for the first time and it turns 4000rpm @ 85 in 5th.

 

That seems a little high to me, but then again, this is the first time I've ridden a Venture at highway speeds.

Unless my brain has taken a vacation today (entirely possible), memory says at 4,000rpm I'm at about 72mph. 4500rpm is around 80. I know my speedo is about +2mph off.

I can't answer the 85mph v. rpm question, but I CAN say that 3100rpm is what my First Gens run at a GPS confirmed 55mph.

so if 3100 rpm is 55, then 85/55 X 3100 rpm is 4790 rpm @ 85 mph actual.

56RPM per 1MPH

Thanks to all of you who answered. Based on the replies, I assuming my 4000+- is about right then. I'll take it out again in a day or so and check other speeds mentioned.

The 56/1mph yields 4760, so I'm in the ballpark.

Thanks again,

You might compare your speedometer to a GPS unit too, to verify its reading right.

Also while at cruising speed in 5th, crack the throttle wide open to see if the clutch is slipping. If the rpm goes up faster than the speed then your clutch spring needs replacing to stop the slipping.

Effective tire diameter has a substantial effect on engine rpm vs. road speed. Effective tire diameter also has a substantial effect upon speedometer indicated road speed.

For instance, the published tire diameter for the MU90B16 Dunlop Elite III is 25.72". The 140/90-16 Dunlop D404 rear tire diameter is 24.73". The D404 is an inch smaller in diameter. This smaller diameter tire effectively lowers the overall gear ratio and increases the engine rpm for a comparable road speed.

The Elite III front tire is larger than the comparable D404 front tire. This difference in tire diameter will effect the speedometer reading as well; the larger Elite III will roll further down the road for each complete tire rotation than the smaller D404, thus the speedometer (which reads front tire/wheel rpm) will be indicating a slower speed than when the smaller D404 is installed.

Then there is the issue of effective tire diameter vs. unloaded tire diameter. The Elite III MU90B16 has a specified unloaded diameter of 25.72" but the loaded effective diameter is probably at least ¾" shorter (as measured from the center of the axle to the pavement). At very high speed, the tire may grow, but the Elite III is a belted tire and belted tires do not grow nearly as much as conventional bias ply tires such as the D404 due to the centrifugal force created at high speed.

Together, differing effective tire diameters will manifest in substantial engine rpm vs. indicated road speed differences.

Here is a screen shot of a table with the First Gen Venture parameters utilized. This calculator can be found here.

But we are talking about 20% lower rpm vs indicated speed.

I can see tires making 5% difference...

But we are talking about 20% lower rpm vs indicated speed.

 

I can see tires making 5% difference...

Yes, 4000 rpm at 85 mph is way too low. Perhaps the OP was mistaken.

I just returned from a 2000 mile trip and spent alot of time looking at my tach and speedo,4000 rpm`s is right around 70,my 92 vr is turning about 4700 at 80 mph.

FYI, a second gen with VMAX final drive, 4000 RPM is 80 MPH.

Which is why I ride around 65-70 now.

I'll be taking the bike out again this weekend and I'll double check my numbers. BTW: I am running Elite IIIs front and rear. I really appreciate the link to the calculator.

Finally took an 80 mph run on my 83 and with the V-Max final drive and the 2nd gen trans, I am running about 4,200 RPM's in 5th gear. At 60 mph, I am running about 3,300 RPM's.

This makes interstate speeds a lot more comfortable now.

RandyA