Rotax 185 engine re-assembly, piston, rings, magneto.

Use ring expander to re-install piston rings, some say that you must use new piston rings every time , I don't think its necessary myself especially if I am de-carbonning every 50 hrs , Id probably replace them after 200-300 hrs

Special Notes
Cylinder head placement is important, you will notice that the top of the combustion chamber has a defined shape, make sure that the shallow lobe that assists the removal of exhaust gasses is placed over the exhaust port side.
 
Also regarding the cylinder head gasket, myself and others I know re-use it several times, as long as you replace it in the original position, I have never had a failure and I put lots of hours on my engines. This is especially handy for just routine combustion chamber cleaning and inspection.

If you did not put a reference scribe mark on mag and case you will have to reset timing using a dial gauge inserted into the spark plug hole. Its a good Idea to fill all electrical connections with silicone to exclude any moisture.

This is also a good opportunity to check or replace the points.