Danny
First I recommend doing an oil analysis to determine what is in the oil.
I have just received a bad blowing Tinny & 2.7 litre engine in the shop.
I had a shot at it by scanner diagnosis and "exterior visuals", but held off on a tear down until the results arrived from Blackstone who I use a lot for my fleet customers to predict problem in the making.
www.blackstone-labs.com/
Results:- High silica in the oil--dust and dirt being injected which "crooked" the cylinders.
Evidence high %age of chrome, cast iron, alum (pistons?) copper and lead (engine bearings?)
Surprise for me it was low on carbon and suspended fuel which rules out bore washing!
So first I need to check the intake for rupture or leakage at the air filter clam shell cover. Then look to see if dirt is in the inlet tract etc before proceeding with the big stuff.
Also some notes on re-ringing etc. Do remember to de-glaze the bores for good bed down of the rings etc. I don't recommend it but the "dooberry ball" hone is often used by DIY er's and Pro mechanics a like.
Reason:- The factory cylinder finish is a plateau hone to about 35 to 42 CLA which gives the bores that cross hatch finish. This aids cylinder oil retention and reduces oil loss from pumping action reducing E figures.
CLA:- "Clear light average" Basically like placing a straight edge over the cylinder plateaus (plateaux??? ) Parlez vous Francais
And measuring the light passing through the valleys on the cylinder wall
What ever you do after first removing the under piston jets and honing is wash the cylinder bores with good old fashioned soap and water and agitate with a stiff nylon brush. This removes all microscopic traces of grit participates adhering to the cylinder hone valleys. After all you don't want these wearing your new rings on start up as they wash out with oil splash.
Once washed, I dry with compressed air and lube immediately with some fresh clean oil to avoid corrosion prior to assembly.
Cheers Dennis