Topic: Is this an aftermarket part?

[Blackhole]

I took this off of a 78 CB750F.  It goes between the case and oil filter cover.  It didn't look stock but I have never owned a 750 Super Sport before.

[Dream750]

That is the factory stock part for your 1978 F.

I installed one of those on my bone stock 750 K4 engine along with a full finned oil pan. When used together, my unscientific oil temp testing showed an average 8.0 degree drop while holding a steady speed and no change during stop and go traffic conditions. This was measured at the oil tank.

[Blackhole]

Thanks for the reply...that answers that. 

[lucky]

The 1978 CB750K had more cooling fins on the engine, and it had larger cooling fins on the oil filter.

So Honda was headed in the same direction as well.

[Terry in Australia]

It was Honda's attempt at putting the cheapest possible "Oil Cooler" on the F2/3. Just a "Heat Sink" really, and not much use.

Honda "Ponied Up the Dough" with the next generation of SOHC and DOHC fours and installed a "Proper" oil cooler with a remote radiator. Cheers, Terry.