2 Strokes ?

[DonHof]

Setting outside drinking my morning coffee, got to thinking. I know a 4 stroke oils like a car. How dose the 2 stroke oil the bearings if it's mixed with the gas??

Don

 

[444]

Two strokes use roller bearings not oil pressure bearings. When the piston moves up it draws oil/fuel into the crank case below the piston, the oily vapor clings to everything and lightly oils. Many two strokes also have grooves and troughs inside the crank case so that when oil/fuel collects and puddles it gets funneled towards the crank bearings. It's really amazing they last as long as they do and I think a real testament to the bearings that while they get constant lubrication when running, it is only very light lubrication.

 

[jimmbo]

The gasoline vapourizes, the oil, as a very fine mist is carried along. It falls out of suspension and deposits itself on the internal parts. Not all two stoke engines use anti-friction bearings, friction bearings(bushings) were used for years. Engines of this design require a fuel mix with more oil. Something to keep in mind when using oils that claim they can be used @ 100:1

 

[flyingscott]

Excluding the DFI motors which uses different oiling systems 2 strk outboards are VERY well oiled. Take one apart once they are just coated with oil inside.

 

[tpenfield]

As stated . . . roller and needle bearings on a 2-cycle, plus the fact that the fuel/oil mix passes through the crankcase rather than the cylinder head. So, the small amount of oil in the gasoline is enough to provide lubrication to those bearings.

If a 2-stroke engine used the same types of bearings as a 4 stroke . . . it would last a couple of minutes . . . maybe. The pressurized oil in the 4 strokes really matters for those types of bearings.

 

[60sboater]

Sustained WOT is ok for them,too(compared to inboards)...think pulling skiers and the loads exerted.

 

[jimmbo]

Some people seem to think that 2 stroke engines only use anti friction(roller, ball, needle) bearings. Not so, there were many outboards that used friction(bushing)bearings, just like the ones on a 4 stroke auto engine. They were still oiled like any non-DI 2 stroke

 

[Scott Danforth]

Some people seem to think that 2 stroke engines only use anti friction(roller, ball, needle) bearings. Not so, there were many outboards that used friction(bushing)bearings, just like the ones on a 4 stroke auto engine. They were still oiled like any non-DI 2 stroke

however the oil/fuel ratio is higher. these motors are 16:1 and 24:1 vs 50:1 of newer 2-strokes

 

[jimmbo]

however the oil/fuel ratio is higher. these motors are 16:1 and 24:1 vs 50:1 of newer 2-strokes

I did mention that in post # 3
But there are people who will claim that brand X oil says you can run them @ 100:1. I guess you can, but for how long is another story

 

[Scott Danforth]

Jim, probably same people that use marvel mystery oil

 

[jimmbo]

Or, Dr. Quacks Miracle Elixir, "Good for what ails you, or your engine!"