I'm at my wit's end trying to get my Brodak 25 to run well.  It was on a fairly light Ringmaster (25 oz) and I could not get it to run consistantly plus it seemed down in power.

The original installation used a 3 oz Hayes clunk tank, a tongue muffler, and muffler pressure.  No matter how rich I set it on the ground, at some point in the flight it would go dead lean and stay there.  Prop was a 9X4 APC with 10% nitro fuel (22% oil, half castor). 

I switched to a metal uniflow tank without pressure and the engine then would hold a setting through the flight except that it was down on power.  On the 9X4 prop with the engine leaned out, there was no line tension.  With a 9X5 prop, the tension was better, but the engine sagged badly on the outside loops of the OTS vertical 8.  I changed plugs (Thunderbolt R/C) with no change and tried 9X4.5 Thunder Tiger and 9.5X4.5 APC props and all were worse than the 9X5.  I took out the needle valve and the hole was pointed down the middle of the venturi and there were no burrs.

Thinking there might be something wrong with the airplane, I switched back to a BBTU OS20FP using the original Hayes clunk tank and the airplane flys well with good line tension everywhere.

The Brodak 25 now has about 4 hours running time on it including the break-in.  I was planning to use it on the Feno I'm building, but not if I can't get it to run well enough to fly a Ringmaster.  I know a lot of people have had good luck with this engine, so I'm looking for suggestions.  I'm considering sending it back to Brodak as defective, but want to cover any simple fixes that we haven't thought of yet if there are any.
Steve

Hi Steve

At sea level here in Virginia we have had that problem with two of the Brodak 25. A head gasket has cured that problem and now only need 2 1/2 oz of fuel 10  50 50 Power Master fuel with a 9x5 prop.
Willis