Topic: Highway RPMs

[longshanks]

Hello gents,

I wanted to get a feel for what my fellow cb750 owners are taching out at cruising speed on the highway. I know it can vary from bike to bike depending on gearing, wheels, and sprocket set-up but with my K6 at 75mph I tach out at 5k rpm. What about everyone else?

[dhall57]

I have a 750K6 also and run the factory set up 18/48 sprockets and at 70mph I'm taching 5 grand. Here's a pic at a little slower speed.

[Bob Wessner]

On my KO, with stock gearing, it runs 15 mph per 1,000 rpm. At 60 mph it is dead-on 4K.

[longshanks]

On my KO, with stock gearing, it runs 15 mph per 1,000 rpm. At 60 mph it is dead-on 4K.

Then yours is the same as mine. Is it okay to cruise at 5k for a long time? I assume yes because these bikes seem pretty rev happy.

[mrbreeze]

These bikes love hi R's. You could run all day at 5-6 K so long as you have good oil and a tuned engine. Mine runs 4K at 70mph (I dropped to a 42 tooth rear).

[Gordon]

On my KO, with stock gearing, it runs 15 mph per 1,000 rpm. At 60 mph it is dead-on 4K.

Then yours is the same as mine. Is it okay to cruise at 5k for a long time? I assume yes because these bikes seem pretty rev happy.

I just did over 600 miles at 6Krpm on my K1, and it ran like a top.  The red-line is way up there because these engines are meant to run fast. 

[Pinhead]

My '79 CB650 with a 17t front sprocket is 4k @ ~55 and 5k @ 70 (it's hard to say exactly because the speedo bounces around).

I'm considering installing a smaller rear sprocket to drop the revs by about 1k or so, as my rebuilt engine (11:1 652cc) has a ton more torque than stock.

[Bob Wessner]

On my KO, with stock gearing, it runs 15 mph per 1,000 rpm. At 60 mph it is dead-on 4K.

Then yours is the same as mine. Is it okay to cruise at 5k for a long time? I assume yes because these bikes seem pretty rev happy.

Should be no problem. I don't care for interstate riding much anymore, but back ... way back when I did, I rode it from Mich. to the tip of Long Island and then another trip to the Smokey Mtns. Much on interstates to get there. If you didn't do 70-75 mph on those, you would get run over. 

[jtb]

I ran 6K all day long with GZ.  My speedo bounces too, but that is 85-90.  Crappy mileage at that rate.

[Grabcon]

I have been using this sight to verify my speed and RPM as well. It is very interesting and allows the user to change up things to really see what happens.

http://www.gearingcommander.com/

[JosepyK]

5K seems to be right around 70 for me with stock sprocket size on my F. But I'll add to the question, what kind of mileage are you getting?

[grumpy]

All stock 18/48, 5K at 70mph, 50mpg on flat interstate.

[mrbreeze]

My '79 CB650 with a 17t front sprocket is 4k @ ~55 and 5k @ 70 (it's hard to say exactly because the speedo bounces around).

I'm considering installing a smaller rear sprocket to drop the revs by about 1k or so, as my rebuilt engine (11:1 652cc) has a ton more torque than stock.

It all depends where you ride. If you do more flat freeway all day long...............do what I did.....(we are talkin' 750...right?).........drop some teeth on the rear sprocket. If you are good with town ridin' and moderate speed twisties....Keep the stock gearing. I sacrifice a little in town but when I do the slab all day....I'd rather be at 4K doing 70 than 5K.