1981 Honda CB750 C...oil

[KenCobra03]

Can anyone tell me what the proper amount of oil used is, when
changing the oil and filter on my 81 Honda CB750?
I just bought another 750 Honda after selling my last one 24
years ago. The Honda manual is confusing me. Ken

[Sev]

Use the site glass or the dipstick... but I would guess you're going to need at least 4 liters.

[mgdavis]

I pretty sure my '79 CB750 is about 3.75 quarts. I know I only buy 4 quarts of oil at a time for it. That's with a filter change.

[KenCobra03]

On my 81 Honda CB750 C, the manual says that the full oil capacity
at assembly is 4.7 quarts. It says when doing an oil change to warm up
the engine, shut it off, drain all the oil out and remove the filter and
then replace all the bolts and then put in 3.7 quarts of oil and then
warm it up and then shut it off and wait a few minutes before checking
the oil level on the dipstick. It says to add the oil up to the full mark on
the dipstick after the 3.7 quarts are in. I put in 3.7 quarts and then it
needed another 1/2 quart more to get it up to the full level on the dipstick.
Ok, so full oil at assembly is 4.7 quarts, I did my oil change with the
specified 3.7 quarts and then I had to get it to the full mark, which was
another 1/2 quart, for a total oil change of 4.2 quarts
4.7 qts, 3.7 qts or 4.2 quarts ... which one is correct? Ken

[mgdavis]

4.2, as long as you're measuring correctly. I think. Sev?

[Sev]

"messed" if I know... you americans measure "poo poo" funny LoL

If it reads full it reads full, you're good. Those are general measurements in the book and don't account for the oil left in the engine when you drain it.

Shrug.

[BuzZz]

Go with the dipstick reading on your specific machine. There are valleys, oil galleries, lines and hoses, pockets and such things formed inside the cases by various components and structures. They will hold a bit of oil even after everything else is drained, so the first fill of a freshly built engine will be a slightly larger amount than all subsequent fills.Variances in casting and machining the cases and parts inside can account for more volume fluctuations.

Whatever the reason, going with the reading your engine is giving you is really all you can do.

[KenCobra03]

It looks like the 4.2 was too much oil and I took out 1/2 a quart
to make it about 3.7 quarts. It read correctly this time.

[mgdavis]

Glad you got things sorted out.

[KenCobra03]

Glad you got things sorted out.

I guess we are in agreement