I agree pops, the STS is the only engine ive had thats different so far
Quotes from STS guy in STS thread:
So I have to notify all STS users that;
1)Be patience to break in your engine. Don't lean it before 2L fuel through it.
2)After 2 liter fuel(about 27 tanks/75cc),replace with a new conrod.
Full message (re: crankshaft breakages)
5. After about 1~2 liter fuel through it, take out the glow plug and turn the flywheel by hand, let the piston pass the top dead center in the sleeve. When you don't have any significant friction or just a little snug, you can start leaning the main needle incrementally in small steps, and keep it around 100~120 oC (212~248 F).
[b]PS.Yes,you need about 1~2 liter fuel through for sure that you can start to lean it. STS's piston is harder than Novas. If you have more patience to break in our engine,you will find our engine more lasting. Mine D3 borrowed to my racer for racing last weekend,he still win the A-champion. In fact I got that engine about half year ago.(practice plus 4 times races) I guessed about 4 gallons through it already. But still have unbelievable compression. [b]
Full message (running in):