Topic: CB750F oil pan compatibility

[carnivorous chicken]

Ran into a hiccup on the CB750F I'm working on, in terms of oil pan compatibility. Here goes:

Mine is a 1975 CB750F, build date 3/75, engine # CB750E-2514066. Went to the salvage yard today, and poked around. Found some 1977 and 1978 CB750Fs, but it was clear the oil pans weren't compatible, or at least it looked that way to me.

I know that the F oil pans are different than the Ks because of exhaust clearance. The oil pan that's on mine is flat but has fins running all the way from front to back (and the PO stripped the plug, JB Welded it in place, and drilled out another spot for a plug, which is now leaking -- hence I want to replace). The 77 and 78 oil pans have fins in the front and then a flat circle toward the back.

So I found an earlier 750F, build date on the neck plate is 2/75. But the oil pan looks more like the later ones, with a flat circle in it toward the back. It looks close if not the same fit, but I don't want to pull the pan and change the gasket if the pan isn't going to work. The parts fiche for 75 and 76 CB750Fs both look like they have the flat circle in the pan.

So what's the deal? Aftermarket finned oil pan? Anyone else run into this?

***Edit: looks like the gasket I have fits the pan I pulled, so I'm gonna cross my fingers but still interested to know if anyone has an idea about this.

[Jerry Rxman Griffin aka MuthaF'er]

Should fit.

[Terry in Australia]

They all fit.

[kmb69]

.....
So what's the deal? Aftermarket finned oil pan? Anyone else run into this?
.....

Pretty sure the K7-K8 and F1-F3 came with the finned, front to back, oil pans. It's a stock Honda part.

[seanbarney41]

I have used earlier k pan on my f3 no problems

[carnivorous chicken]

Thanks guys, gonna dig in tomorrow.

[carnivorous chicken]

Oil pan switch was a piece of cake. So was the filter, switch, although the PO had made some welds to the mounting bolt which made getting a wrench over it a little tough. Still -- lucky that this bike hasn't sit for years, it was last registered in 2016.

Photos of the two pans for comparison (in case anyone else is wondering). And I remember now that I was originally thinking compatibility with the 750A and the other 750s -- the A is the one with the deep pan.

[Terry in Australia]

Is the pan any deeper mate? Or just the finning? I'm pretty sure you could buy an after-market deeper pan for a CB750 "back in the day", but I think all the "non auto" CB750 pans are the same depth? Cheers, Terry.

[seanbarney41]

You got it Terry.  The F2 pan is no deeper, just deeper fins.

[carnivorous chicken]

You got it Terry.  The F2 pan is no deeper, just deeper fins.

That's right, same depth.

[Geeto67]

You got it Terry.  The F2 pan is no deeper, just deeper fins.

F3 engines run a little "hotter" than the earlier bikes. Honda put the extra fins in the pan and a finned collar between the oil filter cover and the block to help with cooling. If you can find those pieces it is a slight upgrade for bikes that get ridden in traffic during the summer months and don't run an oil cooler. Personally I would rather have an oil cooler because in addition to it working better it looks cooler and can actually be seen without having to climb under the bike.

[carnivorous chicken]

F3 engines run a little "hotter" than the earlier bikes. Honda put the extra fins in the pan and a finned collar between the oil filter cover and the block to help with cooling. If you can find those pieces it is a slight upgrade for bikes that get ridden in traffic during the summer months and don't run an oil cooler. Personally I would rather have an oil cooler because in addition to it working better it looks cooler and can actually be seen without having to climb under the bike.

Good to know. So is that pan I pulled (the oily one) a later one? The later model ones I saw at the yard all looked like the cleaner one. I might go back and look for another finned one if that's the case as well as the oil filter cover -- it's hot here in AZ.

[Terry in Australia]

The one with the extra fins is off an F2 or F3 mate, but someone's been messing with it. If it's hot where you are, buy an oil cooler, a few more fins on your sump pan isn't gonna do jack. Cheers, Terry.

[carnivorous chicken]

The one with the extra fins is off an F2 or F3 mate, but someone's been messing with it. If it's hot where you are, buy an oil cooler, a few more fins on your sump pan isn't gonna do jack. Cheers, Terry.

Cheers Terry, might just do...