Topic: Dry Sump - Now I Know a Little More

[Scootch]

Ever since I changed the oil on the CB the other day I had wondered about the various places that oil needed to be drained from the system. Specifically I wondered why I had to drain the oil from the tank. I still don't know exactly why as I thought that draining the oil from the pan would drain it from the tank as well. It didn't work that way. It does work that way on Harley. Harley has an oil tank but no separate drain for the tank. In doing some research I came across the dry sump term. I had often heard that terminology but never looked into it. As opposed to wet sump. Pretty interesting. I still don't exactly know what is different in the mechanics of the Harley system vs the Honda system. But I assume that it has something to do with the mechanics or configuration of the oil pump and/or plumbing. Here's hoping that you all will enlighten me...   

[ekpent]

There is a stop valve in the oil pump that when working correctly keeps the oil in the tank and not flowing down to the crankcase when parked.As these bikes have gotten older the stop valve doesn't always work as well anymore and oil can drain down. No harm per say but that is why its always advisable to check your oil level after the bike has been started and ran awhile. More then one new owner has thought they were low on a cold engine, added oil only to find out later its overfilled.

[Scootch]

Thank you EK!  Very good information to know 👍

[BomberMann650]

There is a slight difference in power between the two engine types.
It comes down to the rotating parts striking a pool of fluid
That being said, not every dry sump motor is more powerful than a wet sump because of the oil system.
There are wet sump engines that can draw excess lubricant away from rotating assembies very efficiently as well

[Kevnz]

Another feature of dry sump is there is (or should) always be a consistent level of oil at the oil pump. Under accelearation, deceleration and cornering G forces, oil can be forced away from the oil pickup in a wet sump engine, leading to temporary loss of oil pressure. That's why racing engines generally use dry sump when permissible.