Bud:

I wouldn't want to take them apart any further than pulling the backplate off to get free access for inspection and oiling.

Don't ever pull a lapped piston out of its sleeve unless absolutely necessary. As they break in microscopic grooves are worn in the surface of the piston and sleeve, when reassembled unless the sleeve is in exactly the same angular relation to the piston it will have to reseat, and the compression will suffer from the added wear of reseating.

And be sure to use a fuel with high lube content, and a large part of the lube should be castor oil. Omega "Heli" fuel is a good choice. Try 10% nitro, 5% nitro should also be fine, if not better. But the 5% will be harder to find. If the lowest nitro you can find is 15% try it, but it might be too much. If yu can't find the Heli blend, go to a larger food store and get "Baker's AA" castor oil, add two ounces per gallon, or a little more I you had to get 15% nitro. None at the food store? Then go to the drug store and get "USP" castor oil.

Hope this helps, and welcome back to the mad world of powered modeling.

Bill.