How long is too long for an engine to sit without oil?

[Nickles]

I bought my CB350K4 about 2 weeks ago at this point. The tank and petcock are a mess and I'm focusing on getting those cleaned and sorted. I drained the engine oil because I was unsure of age and quality. I also wanted to confirm that I didn't have any metal flakes in there (there were none). Is it bad for the engine to sit without oil for an extended period of time? How long is too long? I can perform an oil change, I just didn't plan to do that for a month or so.

 

[ancientdad]

Moved to 350 Engine and Transmission section

Since most of the oil sits in the bottom end after the engine has been shut off for more than overnight, and in our twins the oil sits below the crankshaft bearings anyway (and all but the SOHC 400/450 models are ball and roller bearing mains and rods as well), I don't think letting the engine sit without oil in it is much different than just letting the engine sit, period. As long as dampness can't easily get into the engine (carbs and exhaust on the engine to cover those ports, spark plugs in the head) it shouldn't allow any more rust or corrosion to happen than if it just sat with oil in it.

 

[LongDistanceRider]

It can sit for years that way without a problem, just keep it dry and if it's going to be a prolonged time(years) then plug the intake and exhaust after spraying the inside of the ports with a penetrating oil like WD40, PB Blaster, etc.
Make a tag to attach to the engine that says NO OIL so no one makes a mistake.