Last year I bought a Ringmaster with a Brodak .25 on it. I needed a spare OTS model, and after hearing about the  Brodak .25,. I thought this would be a good combination. I have another Ringmaster with an LA.25 on it and it's a great combo. I have a Brodak .40 on a rather heavy Twister/Shark and it performs well, so I expected similar, but proportional, performance. The engine starts, and handles very well. Has excellent fits and finish and one would figure it would just be THE Bomb on a light Ringmaster. But this engine is gutless! I can only compare it to a McCoy RedHead .19 or a Fox .19 for power, and I would give those two engines a slight edge. I have tried every prop in existance, nitro all over the spectrum, and most common sense oil percentages. The engine always ran well, didn't appear to be over heating, running away or other ill symptoms. It just doesn't have any power! I even checked for a potato in the exhaust pipe! A question for all you other guys using this engine is, what size is the venturi supposed to be? I haven't checked it for size, but being a relatively new, all factory original, I don't have any reason to expect that it is anything other than stock. I have a SIG Primary Force that weighs in the 42 ounce range, and have used LA.25's and FP.25's in it with confidence, but would not even consider putting this Brodak .25 in it. Again, to reiterate, it starts easy, runs nice and steady, needles well, has great compression, but will barely fly a 25 to 30 ounce Ringmaster. My inclination is to open up the venturi 10 to 15 thousandths and see if more fuel will help the situation, but for right now, I have put an LA.25 in it for the upcoming contest at SIG, and it is just night and day more power than the Brodak.

    This may be a silly question, but are you sure the liner is in the right way? Someone could have taken it apart and put it back together incorrectly, or it could have been that way from the factory. A backwards liner will certainly cause weak running (and usually very hot running).

      A Ringmaster goes great with a 15FP. The big problem with 25s is that you need to kill the power somehow, sounds like that's not the problem here.
 
      Brett

Hmmm.  Some of the guys in our club have the 25s and they seem to have decent power.  Maybe not as strong as the FP 25s they replaced in some cases, but nonetheless decent power.  Maybe they will chime in with some of their setup details.  I'm pretty sure Willis has the 25 on his Primary Force, so thats an apples to apples comparison.
One thing I encountered with some of the Brodak and Double Star engines (that are cousins from the same factory) is that some of the spraybars were not flowing fuel very well.  While this usually manifested itself as run issues, I did notice that when replaced with a better spraybar the power increased as well.
More details will help no matter what is amiss, like exactly what fuel, plug and prop seemed to work the best.

   Hi Steve;
      I'm using SIG 15% Champion, Glowdevil R/C long, and the prop that has worked the best so far is a Rev-Up or BY&O 10-5 cut down to 9" and spinning up to about 10,000 RPM. The venturi measures about .247" and that seems to be the norm, and the spray bar measures .147" OD and that doesn't seem like much opening to me. That's what it runs like to me, like it is choked down too far. It runs about 6 minutes on 2 ounces of fuel. Hole in the spray bar seems to be .020" or so, haven't put a number drill in it yet to check. This thing looks nice on the inside. Another response over on Stuka suggested maybe a worn rod, even new from the factory, but I can't detect any play, and I'm used to looking for that kind of clearance. Has tons of compression, needles easily, and even though it isn't making the power I think it should, it runs super steady and holds the needle wherever I put it. I'm tempted to open the venturi about .010" or .012" after I email someone at Brodak about it. I bought the engine second hand, but it is in near new condition, and I would think that if it were not broken in fully, I would be getting run problems, or see black junk in the exhaust. I usually don't have problems trouble shooting engine issues, but this has me stumped. My feeling is that it is just choked down too much and needs opening up, but as far as I can tell, everything is stock and original.
    Brett:  I had not thought about the liner, and just went and checked, and the exhaust side appears to be nice and square in the case opening. The port on the opposite side is much smaller, so I think it's in correctly. It really is a nice looking engine and very well machined. No discoloration or baked on castor anywhere on it to indicate it has ever over heated. I have another one that is bought second hand, but is new in box and may compare that one to this one, and put it on the model after the SIG contest. Maybe mount it on my Flight Streak ARF for testing.
   Thanks for the feedback guys!
  Type at you later,
  Dan McEntee

I have a brodak 25 that was not very fast on  my Super Slow Rat so I decided to put it on my ringmaster and fly it in old time stunt.  I had, i think about a 2.5 oz tank on my ringmaster that was just enough to fly the old time pattern.   At the El Dorado contest it started running much longer on the same amount of fuel.  Must have finely broken in fully.  It really still did not seem happy.    I had some of 30 percent nitro , 23% low viscosity oil Helicopter fuel.    The little brodak came alive on that fuel!  Ran much steadier and with more power than with the Powermaster GMA 10% that I was running.

Has anybody tried opening the venturi up a bit? This is the key to making the Brodak 25 the dominant engine in SSR, and might be helpful for the stunt flyers as well.

B25 now comes with the B40 venturi, it is also the venturi in the parts list.

I have 3 B40's and 2 B25's.  The 40's have a larger venturi bore than the 25's.  All 5 parts lists call out for the same number venturi.

I didn't check the bore sizes because I was in a rush do do something else, so the visual inspection and checking the parts lists was all I could do right now.

All but one B40 are NIB.  The remaining B40 has been on a plane for a couple of years and it pulls like a gorilla.

I just checked Brodak's website.  They list the venturi for the 25 as a BE 1310 and the venturi for the 40 as a BE 1354, so there is a difference.  However, the parts lists that came with my 3 40's and 2 25's all call for the BE 1354.  My 25's are fairly new, so if Brodak has made a change in venturi size, it must be recent.