I own several OS engines and all of them have run great right out of the box except for the BGX. Initially when it was on my test stand I was real impressed with how well it started and ran. After breaking it in I then put in my GP sukhoi and then ran into all sorts of problems with transition, idle, and power. All of the tuning experience I had used on my other OS engines did nothing to solve the engines problems. Mostly that it was running sloppy rich. Yet when I tried to lean the low end out and pointed the nose up at idle it would starve. One time I would adjust the needles and take off and my transition would be fine. I would refuel and go back up and when I went from full power to idle the engine was so rich in the low end that it would take several seconds to burn enough fuel off to come back down to idle (too rich) yet, again, when I tried to lean out the low end I could not get it to stay running at idle when the nose was pointed up. Up to this point I was running the engine with a Bisson muffler swinging a Pro-Zinger 20X8 at 7,500 rpms using Wildcat 10% nitro with 18% oil

Since then I have learned a thing or two and now the engine runs great and I am satisfied with it.

Here is what I did:

I read that the OS rep on RCU's forums tell everyone to replace the medium tubing with large, drill out the clunk and replace the brass tubing to a larger size. (I did that yesterday and the engine performance stayed the same and basically nothing changed. In fact when I flew it last night it had almost no verticle whats so ever- and this is with a 13-14 LB plane! ( I was not pleased) so a friend of mine borrowed me a Zoar 19X8. We ended up leaning out the low speed. We pointed the nose skyward and there was no change at all in the idle speed and transition from full power and back was instant. I put it back into the air and the plane now handled with authority and verticle was nearly unlimited. It may still be a touch rich- but the engine only has a few gallons through it. With the 19X8 it is still running at 7,500 rpm

I am guessing the reason why it didn't idle when the nose was pointed up was because it lack the fuel flow which gave the hint is was lean. changing the fuel lines made it possible to lean the engine out more and the engine was better able to swing the smaller prop.

Considering the plane I am flying it in is a 1.60 class and I am using a 35cc engine I expected to get better performance. But also considering the engine is still breaking in- we'll have to see. For now I am happy with it. I just don't know why the OS rep is recomemding changes that SHOULD be, but is not, in the engine manual!!!!

Hopefully my experience will help others...