ROTAX recommends this service at 50-hour intervals. Why should you consider this service? Pictured below is a 55-hour piston from a Rotax 582 engine. Over time, the natural by-product of combustion will deposit a layer of carbon on the piston crown, the piston rings and the piston ring grooves.
During the power down-stroke, the top, semi-trapezoid ring catches the expanding gasses and forms a very tight seal with the cylinder wall. It is unusual, but possible, that carbon buildups can cause this ring to stick and rob your engine of power.
The lower piston ring is more likely to jam because it is held against the cylinder walls by its elastic properties only. Carbon buildups commonly finds its way into this ring groove.
Also worth mentioning is that excess carbon buildup on the piston dome (.040" or more) can result in contact with cylinder head!
Before:
After:
UltraFlight Aviation's Rotax Decarbon Service includes carbon removal from tops of pistons, cylinder heads, and rings. This service will require the following parts: new gaskets for head, base, exhaust, and intake. The pistons and rings are checked for proper gaps and clearances and reported back to the customer. A before and after photo CD is included.
