Guys I'm having trouble getting this engine to run good,, it runs fine on the ground,, but in flight it runs eratic at mid throttle.
I put a baffle in front of the fuel diaphram plate, it was running worse before I did that,,, I'm turning a 26x10 NX prop
can only get 6050 out of it.... I tried leaning and richening both the low and high ends many times and I just cant seem to find the right combination.... any suggestions,,, short of I should of got a D/A. PS anyone know what the average operating Temp of the cyls should be? Thanks Ron

If the baffle helped then maybe you still have some turbulent air near the carburetor, I suggest a soldered tube on the carb vent hole instead of the baffle and run a line from the soldered tube to the canopy area, this will assure undisturbed air for the vent and may help with the midrange running.
''
Bill

I had the same problem with mine. I even went the solder tube route with no real change in the mid range - idle and full run just fine, transition is perfect, but the mid was all over the place. After about 2.5-3 gallons of fuel it started running better, but still rough in the mid. Changed from Stihl oil, to the Lawnboy that is recomended, things improved a little. The single biggest thing that fixed it was putting air baffles in the cowl to direct the inflow of air over the tops of the cylinders - there are some great examples of how on the BME website. The engine runs so cool now I can touch it immediately after a flight! Sorry I dont know what the normal temperature is. The NX prop getting 6050 is about right (assuming you are still on break in, after about 3-5 gallons it will turn that prop at 6300-6400), you'll be close to 6800 with a Mejzlik 26x10, I recommend switching to it, the engine likes running in the upper 6's better, although I did like the spool up and downline breaking better on the NX, it just didnt give the vertical performance that the higher reving Mejzlik did. Kris will tell you he's turning a 28x10 at 6500, but he's on cans or drugs (suspect the latter), I've never seen one go that high - I keep inviting him down here to Texas to show me how, but no luck so far..

Now, DesertRat, be nice. . . I am running canisters and you always pick up about 250-300 rpm over non-tuned engines. It's a Mejzlik 28-12 at 6350 rpm, btw, and a 28-10 AM at about 6450 or so, and a menz 27-10 at about the same as the AM. . . The NX props are sllightly different from their Menz counterparts. I suspect that airspeed 917 is perhaps a bit lean in his mixture, and is expecting a bit more power when the engien is not fully broken in yet.

My best advice is to give the engine about 10 gallons of break-in mix before switching to 100:1 Amsoil synthetic. . THEN try tweaking for maximum power. Good numbers with certain props will be about 6500-6600 with a Menz-s 26-10, 6600+ with a Mejzlik 26-10 and about 6100-6150 with a 27-10. Best advice with the non-piped BME' s is to prop them for about 6500+ on the ground, because this is where the cylinders porting seems to work best, which means a 26-10 prop in most cases.

If the motor does not "wake up" after the first 10 gallons of gas-oil mix, call keith at BME for further advice. As for coming down to Texas. . why don't you come up to NC for a week or so, DeserRat???