Author Topic: Highway RPM on a ‘74K vs a ‘76F  (Read 632 times)

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Offline tdskip

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Highway RPM on a ‘74K vs a ‘76F
« on: August 26, 2019, 08:46:12 PM »
 Getting a crash course here in the differences between a  K and F,  and it appears they had one notable difference is that the F  has shorter gearing at highway speed’s. At the C 65 or 70 how big of a difference in our p.m. with this be?  I know the tire size etc. will impact at all, but assuming that everything is pretty stock would it be in the 500 RPM range? I came across it while searching but not sure if that’s the correct additional revs that I would be living with on a F?

Is the F a bit snappier around town?


Offline Don R

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #1 on: August 26, 2019, 09:01:59 PM »
 I'm not sure, but when I took off the 17 and put an 18 tooth front sprocket on my 76F the rpm went from 5250 to 4800 if I recall correctly. A more relaxed rpm for my cruising speed. 70-75 area. Going from memory. Sold the F for sandcast money 10 years ago.
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Offline tdskip

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #2 on: August 26, 2019, 09:06:11 PM »
Thanks Don -  so a bit less than the 500 that I bought parked. I bet that still noticeable over a long ride however.

Do you remember if you missed the bike being a bit more eager to accelerate around town with the taller sprocket?

Thanks

Offline 1976cb750f836

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #3 on: August 27, 2019, 04:59:41 AM »
About 20 years ago, when my bike was still stock, except for header and pods, my employee had a 75k, mine a 76f. We rode a lot together. His had pipe and pods also. We weighed bout the same. From a standing start, from any roll on speed, I could pull him, but just barley . About 2 bikes in a 1/4 mile. At 65mph I believe mine bout 500rpm higher. Get the bike you like, not enough difference to matter. If you want more power, the 836 with stock cams is big improvement in tq. With cams it's a different bike. After my 836 and cams I blew him away. I could even outrun our other friends 82 gs750 16 valve.

Offline tdskip

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #4 on: August 27, 2019, 07:31:15 AM »
Thanks, think I'm going to pull the trigger on the F.

Offline Bankerdanny

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #5 on: August 27, 2019, 08:12:59 AM »
The F is definitely snappier around town and busier on the highway. For my long trip earlier this summer I switched to a 2 tooth smaller rear, but now that I am planning to stay local the rest of the season I am going to switch back to stock for a bit more stop light pull around the city.
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Offline Tracksnblades1

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #6 on: August 27, 2019, 08:19:41 AM »
About 20 years ago, when my bike was still stock, except for header and pods, my employee had a 75k, mine a 76f. We rode a lot together. His had pipe and pods also. We weighed bout the same. From a standing start, from any roll on speed, I could pull him, but just barley . About 2 bikes in a 1/4 mile. At 65mph I believe mine bout 500rpm higher. Get the bike you like, not enough difference to matter. If you want more power, the 836 with stock cams is big improvement in tq. With cams it's a different bike. After my 836 and cams I blew him away. I could even outrun our other friends 82 gs750 16 valve.
I'm not sure, but when I took off the 17 and put an 18 tooth front sprocket on my 76F the rpm went from 5250 to 4800 if I recall correctly. A more relaxed rpm for my cruising speed. 70-75 area. Going from memory. Sold the F for sandcast money 10 years ago.

Sounds familiar,

My time capsule, an old 76f, sits still wearing its 18 tooth front Honda sprocket and 45 tooth rear sprocket wrapped with an RK gold chain. This was a popular gearing back then for riding at freeway speeds in Missouri before the mandatory 55.

My life long buddy too, ran a 75k. His was complimented with an open RC sidewinder, breadbox, running 125mains. My 76f had Yoshimura, KN pods, 112.5 mains. He ran 16/48 530 gearing while I ran 17-18/45 530gearing on the F.

 He rode mainly after work in town. I rode to and from work 50 miles round trip. These bikes always ran close. The 75k would jump a bike length initially, then the F would real it in gear by gear by 3rd, the F had reversed the k's lead. I would change to the 17 front sprocket for weekend riding with the pack back then.

Age Quod Agis

Offline tdskip

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #7 on: August 27, 2019, 08:55:38 AM »
Thanks for the experiences, snappier around town with a touring trade-off sounds right for how I will realistically be riding. Easy to picture myself getting to the montains and desert but in truth most of the riding will be in the suburbs with only occasional highway.

Sound like swapping the gearing is straight forward if I feel the need to tweak it.

Thanks!

Offline 1976cb750f836

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #8 on: August 27, 2019, 10:27:45 AM »
With the 836 I now run 18 front. Before the bore 17 was my favorite.

Offline tdskip

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Re: Highway RPM on a ‘74K vs a ‘76F
« Reply #9 on: August 27, 2019, 10:45:14 AM »
With the 836 I now run 18 front. Before the bore 17 was my favorite.

Extra power  it’s on the big bore makes up for the gearing?