So then really your just fine grinding the pistons for a blue printed fit and finish?, with a polished final surface finish?
You previous description of lapping the pistons were of a honing method/motion, which is why I assumed you were after some sort of cross hatched fine finish on the pistons.

My mistake then I guess, I just assumed you were doing something more than just basic engine blueprinting, I'm sure the language barrier is not helping in that matter.

I wouldn't call it your mistake, it s my english issue and i am realy sorry for my english, I just learn it whatever I know in 10 years , without school.
On sleeve yes it is neccessary polishing surface, but piston never polish it, the surface from grinding is realy good. Lapping is for only repair tight fit ( when it comes from factories overtight).
I did many of factory made engines lapped and it is realy proven over the last 10 month, that life of P/S set 30-40 % longer, brak in period just one tank ( 30% open throtel reach), no conrod change after brak in etc. So we can call lapping as correctin action, but not primary. If manufacturers will make fit right initialy, it will be totaly different pictures in power, life etc.

I suppose a fair few "budget" engines could benefit from it then, with the process making up for a lower overall build quality in general.
I have noticed that lower end RC engines do tend to recommend a longer break in cycle than higher spec models, meaning they probably do have to make up for worse original factory fitted spec parts.

I think I may be pulling apart the next RC Nitro engine I buy, just to see just how close the factory tolerance is.
I think I may even pass on the specs of that lapping tool of yours to an engineering friend of mine, could be handy to have something like that around to experiment with.

You don't need engineering friend, just bring pics to any machine shop and they will make it for you. I realy don't know how much they will charge for it, but it is worse it.
I sugest to use lapping compaund 1500 grid, never use diamond base compaund, use silicon carbide oil based.

Actually, my engineering friend owns and runs a machine shop, which is kind of what I meant when I said I'd take the specs/pics to him.

I wish I have this kind of friend here in LA

You do have a friend with a machine shop Ed. If you can give me the specs of the laping tools that would be great. I want to make me one.

hey Steeve. How is going?
I will send you set of drawings for lapping tools.
What machines do you have in your shop?

We have a full machine shop. CNCs, surface grinders, EDM, lathe.... The usual stuff.

@nitrodude & topgun: put me on the backorder list for these lapping tools also...