Topic: 1975 CB750F rear sprocket

[rocks]

What size sprockets/gearing (rear) you are using on 1975 CB750F?
I couldn't find any details in the manual...
My problem is the rpm is really high. When I am at 50mph on fifth gear the rpm is at 4000.
So image going higher on the speed, the engine feels like it's asking for a sixth gear.
Does it sound normal to you?

What is the sprocket size  do you suggest?

Also, I am thinking to change my tires. I am thinking 120/90/19 Front   130/90/18 Rear.
What do you recommend?
Thanks

[Jerry Rxman Griffin aka MuthaF'er]

Stock gearing is 17/48. That'll get you 70mph at 5000rpm with normal size tire