Although I rarely post here I have some intimate knowledge about this particular motor I’d like to share. The saga actually begins some years ago during the 4 Strokes are the best thing ever era. Bob Brooks built a Gordan Delaney Tony and fitted it with a 4 Stroke motor (don’t remember which one or the size but it was the same as what Gordy was using at the time). Although when everything was going well the motor ran nicely. Bob however got frustrated with several internal issues that the motor had that caused the motor to quit unexpectedly. These issues were repaired both times by the factory (same issue both times). When the same thing happened a third time he was done. Again, I don’t remember the details of the motor or what exactly went wrong but I think it had to do with the rocker arms or something. Anyway, when Bob said he was done with the 4 stroke, he contacted Gordy who said he had moved to the Stalker 81. With that, Bob bought a brand new one from a distributor who I think was in Canada (anyway, it was not Tom Dixon). Bob got the motor broke it in and set it up as per instructions from Gordy (same prop, fuel etc.). As I recall there wasn’t a lot of written info that came with the motor itself. After the break in, Bob put it in the Tony and right off the bat had the same going rich in outside maneuvers issue that Charles is experiencing now. Gordy suggested that he move the uniflow tube to solve this issue. That tube was moved numerous times (in both directions – up from where it started and down from where it started) with no changes in the run. I don’t recall all of the things we tried but nothing really worked. Unfortunately, due to pilot error that plane was lost.
Bob then built a P40 that was based on the Delaney Tony numbers. As an aside, it really is amazing how close in scale those two planes are. Anyway, during the building process Bob did 2 things. First, he redesigned the tank compartment of the P40 to accept a more standard shaped tank. Second, he built the nose so it could accept either the Stalker 81 or my RO-Jett 76 without having to change the spinner etc. When Bob finished the P40 he asked me to do the test flights and get the plane trimmed to fly. We started with the Stalker and again right from the git go we had the same problem and virtually nothing we did fixed it. Ultimately, this is what fixed the problem… he pulled the Stalker put it back in the box replaced it with the RO-Jett and all run issues went away. The plane trimmed out very easily and its now basically flip & fly.
Charles in the recent past asked Bob if he could have that motor and although I have no clue about the details of that transaction, I do know that Bob repeated his concern over putting that motor in a plane and the seemingly unsolvable issue that he had. Charles wanted to give the motor a try in his Strega. Although he’s more tenacious about trying to fix this issue than either Bob or I could ever be, and he has tried things that did not occur to either of us, the result is that the motor only runs slightly better than what we achieved. It’s just not right (the motor I mean)
Interestingly, in the past year and a half or so Bob spent an extended period of time in Tel Aviv Israel. By extended, I mean longer than 6 months. During that time he found a CL club and went to a contest just to watch. He met a guy from Europe that was running the Stalker 81 and having excellent runs with it. Bob told the guy of his problems and this gentlemen said that he had exactly the same problems with his motor and was very frustrated. Here's how he solved it …He went to a contest in the Ukraine (I think) and there was a local guy there running a Stalker 81 and was having great success. He asked the Ukrainian gentleman if he could buy the motor. A deal was made and the motor put in the plane that Bob saw flying in Tel Aviv.
My theory is this – Something is just wrong with Charles’ motor. I don’t believe that its anything Bob or Charles has done. I just think it’s a lemon. I know it’s only anecdotal but two people on opposite sides of the earth having the same issue with the same motor and its fixed it by replacing the problem motor.
Regards,
Dave Sabon