Author Topic: 71 cb750, seems gearing is to low  (Read 1107 times)

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Offline motorclocks

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71 cb750, seems gearing is to low
« on: March 21, 2020, 08:20:48 PM »
I'm used to riding old Harley's, pretty new to these higher RPM machines, not really sure if its a no power and high rpm's or just low geared. Little history, I got the bike with head off and already rebuilt, I pulled cylinders off because it had been sitting quite a while, so I had to bore cylinders because for whatever reason couldn't find rings that size to re ring it, bought a big bore kit put it together, just don't know why it doesn't seem to have the power I think it should have, I'm racing it in fourth gear on a residential street, don't have right adapter for compression gage. Timing, valve and ignition seem right on, I have the old bottle top kein carbs I've went thru. Doesn't seem to be starving for fuel, it starts right up really easy, when I twist the throttle, it revs up strong. Don't know if jets or needle position would have any effect from my experience I would think no. Any ideas are appreciated

Offline Kevin D

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Re: 71 cb750, seems gearing is to low
« Reply #1 on: March 21, 2020, 09:25:24 PM »
Standard sprockets are 18/48, or maybe 17/48.
These engines love to rev. Don't lug it at 2000rpm, shift above 5000rpm to get down the road.
71 CB750 K1
106,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline motorclocks

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Re: 71 cb750, seems gearing is to low
« Reply #2 on: March 22, 2020, 10:06:57 AM »
Thanks Kevin

Offline Kevin D

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Re: 71 cb750, seems gearing is to low
« Reply #3 on: March 22, 2020, 03:02:46 PM »
Search around for a dyno run, I think the torque peak is about 6500 rpm.
71 CB750 K1
106,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration