RE: OS engines users Club
No Sandy I didn't have that kind of problem at all. Mine haved always been mounted inverted and performed just fine. I did notice though that when I did a point roll or knife edge that when the plane when from the point to upright the engine would sort of 'burp' for an instant and then keep going. This would happen going to upright from both right and left knife edges or point rolls. It never happened when the plane went from point to inverted, only upright. The engine never quit when this happened. It also didn't happen in a rgular roll.
I don't know how much run time your engine has but several of us here discovered some things about these engines over 4 or 5 years of competing with them: They all need about 5 gallons of fuel run through them before they really run like they should. Until then they will sputter and snort, occasionally quit at a bad time, that sort of thing. They also didn't develop max power until then. Sort of a long break-in period. Once it breaks in completely it will make good power and be trouble free all at the same time.
We ran these engines with some combination of four stroke pipe from Macs or Hatori or whatever just because of noise rules at contests. You can also run a .20 (yes, a .20, NOT a 1.20) size Macs or other brand 2 stroke pipe and it will run fine. No tuned pipe effect of course on a four stroke but it is an economical and effective way to get the job done. I've also run them quite a bit on the factory muffler which has always been troublesome. We keep losing the mufflers and they aren't cheap. Finally went to a flexible header and called it good.
I run these engines basically as follows: Cool Power pattern fuel, 20-30% nitro but never less than 15% as it just doesn't run very well with less. If you got it new it should have 2 needles with it. Use the finer point one. You should end up at about 3/4 of one turn open give or take a click by the time the engine is broken in. You won't need to make much adjustment after that time ever. Idle mixture should be as lean as you can get it and that won't need adjustment again either. It will still idle a little rich. OS Type F plug. APC 14x10 or 15x10 prop. You should be able to tach it between 9400 and 9800 on the ground which will run it over 10K in the air. Don't worry, it is made to run like that. Remember that the blower has to spin fast to make boost unlike the way YS engines make their boost and run around 8200-ish. This engine uses less prop and spins it faster. There are many other plugs and props and fuels that run well in this motor of course but once I got it where I wanted it I didn't feel like experimenting further.
If you like to tinker try this: Pull the head and with a small grinder like a dremel, grind out the ridge inside the head and make it dome shaped. Be careful not to take out too much but when you are done you'll have a hemi engine. It runs even better. Dick Hanson gave me that one and he should know. Voids the warranty though. I don't know why they didn't just make it that way.
Anyway, it's a great motor and you should get many hundreds of max performance flights on it without any real problem. Make sure you run the fuel out at the end of the day. With the pump, regulator and all of that plumbing it will idle 30 or more seconds after you pull the fuel line. If you need to make needle adjustments of more than a couple of clicks, there is a problem elsewhere. If you are making 1/4 turn adjustments there is a problem other than mixture. Whatever you do, don't take the blower apart unless you can do some precision work when it putting it back together. Tolerances are tight and it's easy to get wrong. Wait until you wear it out and then take it apart. I don't think you are having a problem with fuel puddling in the blower housing because there isn't enough room for it. If you run into anything else let me know but this is everything I could think of off hand. Probably more than you really wanted to know.
Rick H.