Hugh,

Usability is a crucial issue here.

I believe the number of members in RCU would be 1/10 of what it is now, if every engine that you purchased required you to disassemble it and to repeatedly 'bake' its parts in the oven and then allow them to cool.

Same goes for lapping compounds (tooth paste was mentioned) and drills...

The easiest thing to live with in a tapered-bore engine, is the 15 minute rich, two-cycle break-in.

Some (most) of the new modelers are not as technically inclined and are likely to damage an engine, if they have to take it apart.

Despite what Super Tigre wrote about their first ABC engines, I don't know of any heat treatment process that these engine undergo during break-in. The piston for sure, and the sleeve, being made of brass which is basically a copper and zinc alloy, is unlikely to undergo anything, at oven temperatures (less than 300 degrees C). So what gives?

Despite the wanting OS manual (I think even the AX still has the same one), the [link=http://www.osengines.com/faq/product-faq.html#q2]Q&A page in their web site[/link] specifies a two-cycle rich break-in for their ABN engines.