Topic: CB750A std vs overbore

[jukku]

Whath is a good estimation of the difference in torque and power between 1. and 2.
1. CB750A with 392 cylinders, 300 std 736 ccm pistons, 392 head, 393 cam, A carbs standard bore!
2. CB750A with 300 cylinders, 300 std 832 ccm pistons, K7? head, F 2 cam, K/carbs? Overbored!
 
Is there some differences between the above mentioned 1. combo and
3. CB750A with std unmarked cylinders, 393 std pistons, std 393 unmarked head, 393 cam, A carbs?

My CB750A with Wiseco 836 ccm 10.25 kit, F2 cam and K7 carbs feels really hot on my sidecar.

Three months to next driving season.

I´ll be greatful for all info!

[Don R]

  #1 and #3 will have the HP of an A. #2 will have the HP of a strong K depending on the bore.
    I think the A has a similar cylinder pistons and head to the 392 if not the same. The one A that I took apart seemed to anyway.

[bear]

My CB750A with Wiseco 836 ccm 10.25 kit, F2 cam and K7 carbs feels really hot on my sidecar.


An "A" will definitely generate excessive heat running a sidecar. A wet sump, torque converter, larger bore and the sidecar adding extra weight and fontal area all contribute.
I intend to have my 750A sidecar on the road shortly and I expect that there will be heat issues to deal with.
If that's the case I will start with a bloody big oil cooler, advance the cam timing a little and run the jetting a little richer.
I'll see what happens after that.

[jukku]

There was heat problems with one of my first A/sidecar one summer with air temperatures well over 30 degrees celcius. The problem was solved with oil cooler mounted on the sidecar frame. Same cooler is commonly used on CB750.
My A/Terraplane sidecar had a cooler from the beginning with the Wiseco 836 10,25:1 big bore. No temperature problems ever.