Be sure and check good up inside the piston. Any sand or debris there will find it's way down the rod and into the lube oil holes and thrash that new big end bearing. That is probably the reason the bearing it came with needs replacement after only the factory test run? Another good place to check is to press out the cylinder liner. I got a ton of sand out of the cylinder casting on my 6/1. The liner press out quite easilly on a drill press using a couple of wood blocks. Some have issues with excessive liner protrusion(greater than .010") out of the top of the cylinder causing head gasket leaks. Sand or crud under the lip of the liner near the top can cause it not to seat on it's shelf in the cylinder casting properly.
Another key thing to check is the backlash between cam gear and idler gear, and idler gear to crank gear. I do this with a magnetic base dial indicator and a rod or dowel thru the crankcase door. It is real easy to do with the cylinder and piston out of the way and no real loads on the camshaft. Unfortunatly the machine tollerances in india are not so hot, and sometimes the idler gear pinion bolt is off. Excessive gear backlash will pound the idler gear pretty hard, sometimes breaking it. The bronze idlers are more tollerant of this. An offset idler bolt can be used to dial in this backlash to acceptable limits(below .008"-.010"). Mine was around .025 on one of the measurements. An offset idler bolt got this down under .007" and got rid of a considerable ammount of gear train noise.
Did yours have any half paper gaskets under the cylinder base? That is one way they make up for machine errors in the block. When you do your lead squish measurements, put a piece of lead out near each edge of the piston directly above the piston wrist pin. The difference in lead squish across the piston will show you any crank/rod/cylinder misalignments and wether you have the propper ammount of half gasket installed.
It would be nice if the assembly plants where these things are made would discover the pressure washer...
I sure like mine, it is a lot of fun to run, and keeps the lights on for not a lot of fuel, when the grid can't.
Good Luck with yours.
