Question for you guys?

[Lincoln Highway Bullitt]

Ok guys I just finished my build and have not ridden for about 10 years. I was riding today and thought the motor was turning pretty high RPM's at 55 MPH. I may be wrong but it just seems that way or maybe my speedometer is off. It was a 1980 CB750F that I made a Bobber out of it. It seem to be turning 4500 RPM at 55 MPH. Does that seem right?

[Re-run]

Seems about right for an F model. The F models were geared a bit low and turn higher rpm at the same speed as a K. At 70, my 78K turns about 6000 rpm or something about there. I would say you are about right on.

[shinyribs]

I had the same concerns being new to both bikes and Cb750's. Mine is a 76 F. From what i can gather the stock gearing should be a 18 front sprocket with a 48 rear. Mine is 18/45 and I turn 5,000 at 70 mph and 4500 at 60 mph.

[Half-Caf]

I also noticed that it seemed a bit high. So... is it better for the engines to change the gearing?
Maybe its not that big of a deal?

[rrgunslinger]

My 73 turns 4000 at 50mph.  I think that is to high so I will eventually change it.

On Mon, Mar 12, 2012 at 4:16 AM, Half-Caf [via Honda CB750'S] <[hidden email]> wrote:

I also noticed that it seemed a bit high. So... is it better for the engines to change the gearing?
Maybe its not that big of a deal?

Chicago, IL
1980 cb750f SS

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[Piute]

   Lil about the S.S. models ,They were made as more a sport bike as one would be for that year
 so lower gears quicker acceleration.
   Now the K I believe were for cruising even touring,"fairings, bags, and such were common on them,
 So now some turn the "K" to cafes with those gears
   , as my "F" I need taller gears for my touring and hwy. use ?

[Re-run]

Everyone needs to remember that these bikes are inline 4s, they are made to rev up. The sweet music doesnt begin till close to 5000 rpm. You can't think vtwin with these bikes. The rpm is something to get used to.
To change gearing, smaller front sprocket or larger rear = greater accel but higher rpm. Larger front or smaller rear = lower accel and lower rpm.
Also 1 tooth on the front is = to 3 on the rear approximately.

[LukeM]

Agreed.  Many's the time my son nailed the throttle on his CB550F, watching it go to the redline and a little bit more.  It just keeps coming back for more. I think the Honda engineers got it right with these bikes: they seem happiest in the higher RPM ranges, with occasional excursions into the higher end (7000-8500).  They do sing nicely up there, don't they?

My other son's Miata with the 1.6L engine also makes nice music in the upper RPM ranges. Same deal: smaller motor, tuned nicely, ready to rev.

Luke M
(getting almost warm enough to ride....almost)

[shinyribs]

Yep,these lil dudes are awesome motors. Luke you mention an occasional trip to 7-8k...mine is nearly dailyI cant get enough of that sound! Rerun is right too,these bikes just rev.It's what they do

Lincoln highway,I see your avatar and the race car in your shop. If you try to think about them as you would a V8( like I did) they seem crazy. Now that I compare my Honda engine to my V8's....they seem to pale in comparison. These little 4 bangers are far more advanced,and better put together ,than anything Detroit ever pumped out. Just let it sing,its built for it.

[Lincoln Highway Bullitt]

Thanks guys. I was just concerned because it is my first bike in a good many years and I didn't want the summer fun to end because of an over site that could of been prevented. I took it to the high end of the tach today. You guys are right! They have a sweet sound. I can't believe how hard those motors pull when they hit 7000. That's when mine really came to life.    
       Shinyribs that race car of mine is fun and has a thumper cam but your right about those 4 bangers. Go baby Go!

[shinyribs]

Aah,I love the Thumper cams. What a wonderful invention. Are you happy with yours? Some guys complain of loss of low speed torque,others dont. I ve never owned one personally.

Oh,if you think 7000 is good...wait til they hit 8500! Like a whipped dog