Ralphw
12-12-2004, 12:02 AM
OK, trouble in paradise today.
My brand new (8 tanks) 50 SXH scored the piston and sleeve at the exhaust port. Not running lean at all, the backplate was cool to the touch after repeatedly landing and checking, plus plenty of smoke.
This was the first flight where I began to open it up a little bit and start flying around some. Everything was running great, loads of power and no bogging. Plenty of smoke at all throttle settings and no lose of smoke with rapid throttle changes. Headspeed appeared to be a little high but not excessively so (can't be certain of the headspeed as the motor died before we got the tach on it).
Setup was an MP2Q for the JR gearing, 60B carb, and CP 30% in a Venture 50 conversion. Anybody have any ideas as to the cause?? I've had one person advise against 30% with the 60B carb, but rich is rich regardless of the carb and this was RICH. Prior to this flight the engine was operating very very well, easy start, smooth idle and good power, even though the mixture was on the fat side of rich (from what I could tell since I hadn't really pushed it at all).
After pulling the motor, then the piston and liner, there is obvious scoring of the piston and liner at the exhaust port, but ONLY at the exhaust port. The ring is cooked at the same location, but there is no evidence of anything going up or down into the rest of the engine. Upper and lower sections of the sleeve are very clean and do not look overheated. No evidence of debris in the head dome area or in the case.
The only thing we could come up with was possible debris from the manufacturing of the muffler getting pulled into the exhaust port and causing the scoring but that seems a bit of a reach.
Any ideas anyone?? I'd love to know where I went wrong, IF I went wrong or was this just a freak thing.
My brand new (8 tanks) 50 SXH scored the piston and sleeve at the exhaust port. Not running lean at all, the backplate was cool to the touch after repeatedly landing and checking, plus plenty of smoke.
This was the first flight where I began to open it up a little bit and start flying around some. Everything was running great, loads of power and no bogging. Plenty of smoke at all throttle settings and no lose of smoke with rapid throttle changes. Headspeed appeared to be a little high but not excessively so (can't be certain of the headspeed as the motor died before we got the tach on it).
Setup was an MP2Q for the JR gearing, 60B carb, and CP 30% in a Venture 50 conversion. Anybody have any ideas as to the cause?? I've had one person advise against 30% with the 60B carb, but rich is rich regardless of the carb and this was RICH. Prior to this flight the engine was operating very very well, easy start, smooth idle and good power, even though the mixture was on the fat side of rich (from what I could tell since I hadn't really pushed it at all).
After pulling the motor, then the piston and liner, there is obvious scoring of the piston and liner at the exhaust port, but ONLY at the exhaust port. The ring is cooked at the same location, but there is no evidence of anything going up or down into the rest of the engine. Upper and lower sections of the sleeve are very clean and do not look overheated. No evidence of debris in the head dome area or in the case.
The only thing we could come up with was possible debris from the manufacturing of the muffler getting pulled into the exhaust port and causing the scoring but that seems a bit of a reach.
Any ideas anyone?? I'd love to know where I went wrong, IF I went wrong or was this just a freak thing.