The engines are made of aluminum as you know. In some small lawn mower, almost all week wacker, chain saw, etc…engines do not have steel sleeves. It’s an aluminum piston, soft ring to aluminum bore (cylinder). There is excessive piston to wall (cylinder) clearances and oil slingers to keep the two well lubricated. But they never last as long as sleeved engines of the same variety.

With an R/C engine, there isn’t any oil in the crank case to be “slung” for lubrication. 99% of your 2 stroke R/C engines are not ringed therefore they have to have very close or “tight” clearances in order have compression. All the while letting the lube in the fuel to seep past the piston and lubricate all the moving parts in the engine.

If it were not for the steel sleeve design, every R/C engine manufacture would go bankrupted because everything they sold would soon seize up. These engines can’t be over bored to the “next larger size” such as with an automobile engine.

It just so happens that many a year ago, the sleeves where not replaceable but some really intelligent person said that it should be and it was so. And I’m so happy that he did.

The sleeve, piston as well as all the parts of your R/C engine is replaceable. It’s a luxury you and I share.

Relish in it.