You forgot to mention Bob Brassell of Jett Engineering... http://www.rcuniverse.com/forum/m_1890371/tm.htm

I would explain it this way. The person the specified the material(s) necessary to manufacture the engine “KNOWS” what its made of and what the Physical and Mechanical properties of the material are. “Brass is NOT Brass” It can reach a Rockwell Hardness of 95 on the “B” scale. That’s some pretty hard BRASS.

“I believe” that the brass cylinders in THESE engines start out as tubing, NOT solid bar stock that some other engine manufactures may use. Brass tubing has the mechanical and physical properties that allow it to be drawn on mandrel. I also believe that the taper is formed using a burnishing tool that forms the taper and creates the surface finish at the same time. Roller burnishing moves the material on its surface and creates a “Rind” like a watermelon. The surface on the “inside” in the case of a cylinder is much harder as it has been “Work Hardened” . You can experience this process buy bending a paper clip. The first bend, bends easy, keep bending it and it will work harden and break.

ALL the Engineers that I know take great pride in their work. I have a real hard time believing that an Engineer would allow the PR department to write the instruction manual for the engine that they just designed “INCORRECTLY”……

When Bob Brassell wrote:

There is some good and bad information out there about break in procedures for ABC type engines...... some info is a mixture of both. In general, a procedure outline by an engine manufacturer should be followed as written.

Other engine manufacturers have their noted procedures. The procedures depend a lot on materials. Jett uses special alloy aluminum for all pistons, and all sleeves are TRUE chrome plated. For a Jett, that first minute of being rich does no damage to the piston or sleeve. It is no different than starting a Jett or any other ABC engine when cold and at idle. The procedure outlined in the instructions and on the web site is very tried and true. Always follow it with a Jett engine, and the engine will run flawlessly.

Something of note. 'Taper bore' engines and AAC/ABC engines can be different. Some have a 'fixed' taper that does not change or changes unevenly. A well-designed AAC/ABC engine has a taper and piston/sleeve fit that DOES change. Both the piston and sleeve change with temperature. When the engine is cold (at start) there is an interference that you can feel and hear turning over the engine... with a Jett, the audible 'squeak' is a good thing to hear! As soon as the engine starts (for sport engines, at idle) the engine begins to warm up, creating the appropriate fit between piston and sleeve. As you take the engine to full power and it reaches operating temperature, the fit becomes optimal, and you will hear the engine rpm increase to its full potential. If anything, you want it on the 'tight' side.

Perhaps if Mr. Le fou had followed the instructions in his manual he would not have had to buy a replacement piston and cylinder for his new engine…

You can do what you want…I’m just saying. “Everything is not as it appears”.