Well I finally got the Echo 3100 apart. It does have ball bearings=32mm in Dia. The piston is just shy of 36 mm Dia. The Piston, rings and crank assembly weigh 300.7 Grams or about 10.6 OZ. I wonder if a good bearing dealer would have same size and maybe beter quality for less than the cost at a Echo dealer? Any help in that department...would be appreciated. Here is the engine apart. New crank seals for sure also. Thanks Capt,n