Topic: Another CB550F mpg question?

[Pinhead]

Do you mean the cylinder walls having the oil washed off them under an extremely rich condition?

Yeah, stuff such as low compression due to bad rings/washed walls, semi-seized bearings, low oil level, drive chain worn out and/or too tight, preignition/detonation due to carbon build-up, etc, etc, etc.

[crazypj]

26~43mpg on mine when it was stock, depending how I rode it, (usually closer to lower number  )
 With 591 kit, cam, exhaust and K&N filters, consistent 41mpg, 54mpg if I took it easy
being in too high a gear at lowish rpm when accelerating wastes a bunch of fuel

Didn't you change the carb jetting, sprocket gearing, too?

 Only changed rear sprocket 1 tooth smaller and jetting was quite a bit richer. Spent a lot of time getting mid range right though

[brianzenk]

I'm riding a Honda cb550 1976
It is getting 39 MPG 
Its stock with lots TLC