The 60T and 90TS engines are the smoothest running engines I have.

This comes at a sacrifice. These engines have 7 ball bearings in them with 4 of the bearings in blind pockets.

To take one apart and put it back together is almost like taking a half a real light airplane engine apart and reassembling it.

The rods have caps. The cylinders have to be pulled and the crankshaft put in an exact postion to get each rod cap off.

Reassembly requires a lot of thought as to just how to get the rod cap back on in the correct orientation.

But the engines start so easy and run so nice.