ORIGINAL: tsyssa
Did you adjust the needle settings? When it was run here it was very humid and 50 degrees. What is your altitude?
Just ran the Mejzlik 18x6 on a new engine with 17 minutes running time....turned 9090 rpm for peoples reference on props. Its about 65 out today...180 Ft ASL.
Again for reference: a few years ago I had an OS 1.60 in a plane, and a flying buddy had a Saito 1.80. He bought a Mejz 18x6. His Saito turned it (from memory, so don't quote me) ~8600 and my OS turned it ~8800 - 8850 on a Bisson muffler, and either Cool power or S&W 15% fuel. In New Hampshire, maybe 200 ft elevation, mid-80's and HUMID.
Basically this new engine has the potential to be MORE powerful than my OS 1.60, weighs ~8-10 oz LESS (my OS was as I recall 49 oz with muffler/pump/mount, the Syssa engine is 38 oz rtf), and requires HALF the fuel load! Sounds like a great replacement for the OS.