Just getting back into C/L after a layoff. I was rummaging through my stuff and I have a brand new Fox 15BB and a plane just waiting for it to go on. I was wondering what type of break-in procedure these little engines require.

Thanks!

Hi Travis,

The Fox 15BB is an iron piston engine. You should use fuel that has around 22-23% oil.
A little extra oil won't hurt as the connecting rod isn't bushed. I would use 1/2 castor 1/2 synth oil fuel.

Randy Smith has great advice here: http://stunthanger.com/smf/index.php?topic=4037.0

Do short runs to heat the engine up, letting it cool completely (cool to touch) between runs.
You want to heat cycle that piston/cylinder until they stabilize. As per Randy's advice above,
start with 4-cycle rich wet runs. Follow Randy's advice about progressing from there.

Since it is a small engine you can use about 2oz or less per run.

Attached is a scan that I found on-line. It is not that much help, in my opinion.

-Chris

Hi Travis,

The Fox 15bb w/o muffler weighs about 5 3/4 ounces. The Akromaster, I believe was designed for the older Fox 15 steel fin engines, which weigh a little less than 4 ounces. So plan accordingly during the build - maybe shorter nose or longer tail. Otherwise will you need to compensate with tail weight.

That Fox 15bb muffler comes in at 1.2 ounces.

-Chris

The easiest way to fix CG on older kits is to move the wing forward. Mark wing centerline with a pencil, mark 3/4" point in front of the current cut out and cut out the shape as needed. Once the wing is glued in, used scrap balsa to fill in fuse opening near the trailing edge.

Although sometimes the use of older kits and designs attracts rules and conformity, and in this case a prop extension that moves the bulk of the engines mass backwards whilst keeping true to the original outline may be more appropriate.