rpm

[doc_dr1969]

at 55 mph in 5th gear im running about 3500 rpm seems rather high for me but been told that is normal for honda.new clutch plates just put in thought that could be the problem but was not any suggestions thanks

[detdrbuzzard]

hello and welcome to NHF doc_dr1969, what are you riding

[cjbear11]

Actually, I think that sounds about right for these bikes. My bike is shaft drive, but if I remember right, at 55 mph, I'm in about the 3500 rpm range. I'm assuming you have the stock sprockets on your bike?

[doc_dr1969]

thanks forthe help i sure do apprieciate it its a 750cb nighhawk all stock thanks again

[LOKi]

That's about right. The only speed I consistently hold is 78mph and that is 5K. Actually it's the RPM's I like to hold right at 5K. When you get above that the MPG goes way down.

Are you new to motorcycles or just new to standard motorcycles? When I first got the NH I thought there was something wrong too. RPM's way high. But turns out that's just how motorcycles are geared. At least Japanese bikes are.

oh yea  to the forum

[hppants]

I realize models differ, by my indicated rpm on my 700s is much higher.  Don't quote me, but at 60ish mph, I'm turning around 4500 in 6th.  Maybe my tach is off?  My front and rear tire are one size larger than stock, but that should make the rpm's lower, not higher.  I'll get a more accurate reading this weekend.

[Adam Roby]

It's funny now that you mention is I thought the same thing when I got my NH.  My old sabre was an 1100 with 6 speeds, would shift from 3rd to 4th at 8,000 RPM and 115 mph.   I don't go that fast on this bike, but it is running around 4k at 65 mph maybe?

[Moedad]

My tach is broke. It shows 3k rpm with the motor off. At 55mph in 5th gear it's just hitting redline and at 80 it's pegged all the past redline. Kinda bothersome at times.

[cjbear11]

My tach is broke. It shows 3k rpm with the motor off. At 55mph in 5th gear it's just hitting redline and at 80 it's pegged all the past redline. Kinda bothersome at times.

I don't know if it's possible to do, but it sounds like your tach needle just needs re-calibrated. You'd have to take the tach apart unless you can just take the glass out, but it sounds like you should be able to just reset your needle to zero when the engine is off. Just a thought...

I realize models differ, by my indicated rpm on my 700s is much higher.  Don't quote me, but at 60ish mph, I'm turning around 4500 in 6th.  Maybe my tach is off?  My front and rear tire are one size larger than stock, but that should make the rpm's lower, not higher.  I'll get a more accurate reading this weekend.

It's been a few months since I've had my 650 out, but I think at 60mph, my tach is reading about 4k. Not sure how much different the gearing in the 700 is from the 650, but 4500 or so doesn't sounds off to me.

[hppants]

I'm a little confused.    Supposed that's not too hard to do.   

My front tire is a 120/80, stock is 110/90 and I'm not sure which one is taller.
My back tire is a MT90, stock is 130/90 and I believe these are the same size.

When my speedo reads 60, my gps says 58.  Close enough.
When my speedo says 60 (6th gear), my tach says about 4800 rpm.  Way more than Pauls' page spec of 4373 rpm at 60 in top gear (for an '85 700s - were the final gear ratios changed?)
When my gps says 60, my tach says just a hair below 5000 rpm - call it 4900.
When I lower my engine speed to about 4400 rpm, my speedo is saying about 53 mph.

Wonder if my tach is off?    How would one check that?

[Brittles]

If my calculations are correct the stock front tire is just 3mm taller than the 120/80 your currently running. Not enough to make much difference.

I can't remember what my rpm's are at 60, but think it's more in line with your numbers. I'll check next time I ride.

[hppants]

Brittles - thanks.

Your calculation on the front tire seems correct to me.  Pauls' page had the speedo dead on at 60 mph.  So, my tire being just a hair small makes sense on the GPS v/s indicated.

I'll be interested in hearing your RPM numbers.

[Brittles]

Brittles - thanks.
I'll be interested in hearing your RPM numbers.

I think the rain is finally supposed to end tommorrow. Been raining for the last four days.

[cjbear11]

120/80 and 110/90 refers to the thickness in mm, and the side wall height in terms of a percent. The side walls height is 80% of the thickness on a 120/80 tire, which comes out to about 96mm. On a 110/90 the side wall height is 99 mm.

I'm a little confused.    Supposed that's not too hard to do.   

Yea, idk. Probably not possible. I just got lost in thought  LOL.

[hppants]

So, my current tire has a circumference of about 3% more than the stock tire.  60 mph registered on 58 actual is about 3% more.  Mystery solved on the speedo.

Now, let's see what others show on the tach.

[Brittles]

I checked mine today and at an indicated 60 mph my tach is showing a tad over 4600 rpm's. I don't have a gps to know my true speed. Running a stock size front tire and a 150/80 on the rear.

[fishmeister]

  Mine was pretty much redlined all day and I had a hard time reading the tire sizes spinning that fast.

[skramer360]

Speedo indicated 60 mph was 4800 rpm's for me.

[hppants]

Now this is interesting.

Brittles and I have '84's, Skrammer has a '85.  I don't think any of the gear ratios or final drive ratio changed between the 3 years on the 700s.  Does anyone disagree?

Brittles, if you believe Paul's page, then with the stock tire, your speedo is dead on accurate at 60 mph.  And considering that, at that speed, you are at least 200rpm below me.
 
Skrammer's numbers seem to match mine.

I suppose I'm not going to test the rev. limiter for the sake of this experiment.  I do have access to a mechanical tach (used in the elevator industry) that I have used on outboard flywheels to check boat tachs and calculate prop slip  (BTW - for small wheels, the Powertek T-series is the most efficient propeller I have ever seen!).  What I need is an old fashioned cage engine tester with a tach - I'll look around and see what I can learn.

[doc_dr1969]

 i was out riding today and i was at 65 mph at about 4300 rpm