creightoncarr
05-14-2007, 09:04 AM
I have an OS 61 SX-H which I am about to replace with a 91. Before I do, however, I've been having some problems with the 61 that I'd like to figure out. The engine is only a couple of weeks old and has never run quite right. I'm using Powermaster 30% and I flew the first couple of tanks making adjustments to the needles. I obtained a good idle and smooth throttle response through the midrange and up through the high range. I then opened up the high needle a couple of clicks to let it run slightly rich.
I then started to fly it a little harder (well, relatively speaking, that is - it is only a 60 sized engine after all) and about two minutes through the first tank the engine cut out. It did not sputter and die, does cut out, almost like it seized, but I was still able to turn it by hand very easily and smoothly. I tried to restart but it would not catch at my previous idle throttle position of about 10% I couldn't get it to catch until I open the throttle about 40%, at which point it caught and started to spin up quickly. I decided to call it a day.
Next day I went out to test it again. The engine started fine. I checked the needles and the idle and throttle response seemed good. Again, however, after flying with the throttle wide open for about a minute, the engine cut out. And again, I could not get it retarted without opening the throttle about 40%. Adjustments to the idle mixture made no difference. I've tried different plugs, different fuel and running without the pipe and the results have been the same. Further, even though I've got the mixture set rich, when it does run, the engine runs HOT. The head temperature was close to 250*F.
Is there something I'm missing? I haven't had any problems like this with my OS 50's. Once I've set the needles on those they've always run very reliably. Does it sound like the carb is not functioning properly? I've disassembled the engine and there does not appear to be any internal damage. I don't have a compression gauge, bu the compression seems good when I turn it by hand. Any advice would be greatly appreciated.
I then started to fly it a little harder (well, relatively speaking, that is - it is only a 60 sized engine after all) and about two minutes through the first tank the engine cut out. It did not sputter and die, does cut out, almost like it seized, but I was still able to turn it by hand very easily and smoothly. I tried to restart but it would not catch at my previous idle throttle position of about 10% I couldn't get it to catch until I open the throttle about 40%, at which point it caught and started to spin up quickly. I decided to call it a day.
Next day I went out to test it again. The engine started fine. I checked the needles and the idle and throttle response seemed good. Again, however, after flying with the throttle wide open for about a minute, the engine cut out. And again, I could not get it retarted without opening the throttle about 40%. Adjustments to the idle mixture made no difference. I've tried different plugs, different fuel and running without the pipe and the results have been the same. Further, even though I've got the mixture set rich, when it does run, the engine runs HOT. The head temperature was close to 250*F.
Is there something I'm missing? I haven't had any problems like this with my OS 50's. Once I've set the needles on those they've always run very reliably. Does it sound like the carb is not functioning properly? I've disassembled the engine and there does not appear to be any internal damage. I don't have a compression gauge, bu the compression seems good when I turn it by hand. Any advice would be greatly appreciated.