You may be on to something. My friend noticed a little oil at one of the head bolts. It turns out it was a little loose. I snugged down all four bolts. I ran a full tank on the ground just trying to get it to die again and you know what it did but it was becuase it was out of gas lol. We sat an pondered for a while and it turns out it was out of gas.. I'll have to to check the head bolts again and see if it's still leaking if it is I'll order a new gasket but my hunch is that I may have the same issue as you did. The reality is that I did notice a few other things when I started taking things apart. Like both carb bolts were loose, I had a ton of junk in one of the small screens in the carb and the fuel line in the tank was floating as the clunker had fallen off. The gas was about 1 1/2 years old. The plug looked good and the battery seems to be fine and all of the fuel lines except for the one in the tank looked to be in good shape. So at this point I can't say with any certainty that the problem is fixed. I did replace the clunker with one that has a screen the other thing I noticed is the manual said use medium fuel line and mine had large fuel line other than that I'm mystified. So if she dies mid flight again I'll replace the head gasket.
ORIGINAL: frieshoo
$50,
I owned the same engine and same plane. I ran a Xoar laminated 23x8 on mine. 6700rpms... very strong motor...
As to your original question...
Make sure the gasket between the cylinder and case is not leaking (and sucking in air). My engine had this gasket replaced 3 times... it's a problem area for the engine..
My engine would start easy, and run fine, until about 10 minutes into the flight... and bam.. she would just shut down... I changed everything, fuel, plug, fuel line, tank, etc.... I even baffled the cowling.... that help some... but the engine would still just shut off...
I replaced the gasket and it fixed the problem... but the replacement gasket from Horizon would fail after a few flights... It's really a same, because the engine was smooth... and a big time power house...
Did Horizon tell you the torque to tighten the bolts down? I'm assuming the head and may be aluminium and the rest of the casing is steel? I would think that if the engine overheats it could loosen the bolts causing an issue.
Oh I have a BCM (Bisson Custom Muffler) pitt's style muffler I belive they are called. I thought they were supposed to perform better than the stock muffler and are a little lighter. Maybe I'll get a new gasket and get a CF prop see if I can reclaim my 1000RMP's