Ed Cregger
Posts: 7744
Joined: 1/31/2002
From: Ringgold,
GA, USA
Status: offline
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Nowhere does it say that the .55AX is designed to lug large propellers. Not like a .61 SF or RF is designed to lug large pattern props.
When talking to the crew at Jett Engineering, I was told not to exceed an 11x6 when using their primo power boosting muffler. I suspect that they know a bit more about engines than the marketing folks that wrote the US OS operator's manual. Lots of importers write their own manual for various engine brands.
One reason they (US importers of OS) might not favor smaller props is because they know that, unlike previous OS two-strokes, the OS.55AX connecting rod's upper end is not bushed. Had I known this fact before purchasing, I would not have bought them. This is flat out cheap construction. Perhaps they will wise up and eventually offer a connecting rod that is properly bushed on both ends.
I would try an 11x7, or even an 11x6 when not using a high performance muffler, such as the Ultrathrust or Jett muffler (never can remember its name). Using one of the high performance mufflers or a pipe, I would use an 11x6 or lesser prop (10x7 or 10x8). Remember, the .55AX is just a glorified .46AX, not a shrunken .61FX.
Without the bushing in the connecting rod's wrist pin end, you MUST use a fuel with at least a smidgeon of castor oil, or the upper end is going to go oblong on you.
Ed Cregger
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Artisan
"Flying models since the Fifties - I'll get the hang of this yet!!!"
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> RE: O.S. 55AX thread 
RE: O.S. 55AX thread - 
RE: O.S. 55AX thread - 
(and I bet we will be here for a much longer time 
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