ORIGINAL: opjose
No it can't.
I've heard a bunch of people make exactly the same arguement with exactly the same ''engine dying in flight'' problem...
But I've found plumbing problems in about 60% of those situations... things which the pilot was SURE is correct, but it turns out there is a leak or some other problem.
Don't rule out ANYTHING until the engine is running correctly.
I already have a bubble-less clunk in the tank and the tank is well padded.
This time I tested the fuel lines both in the tank and going to the carb muffler and filler. Basically, I held them underwater and blew as hard as I could into the tubing with one side closed with a fuel dot. The tank does not have any leak.
ORIGINAL: opjose
When warm you should feel some resistance at TDC if not, check your cap screws on the cylinder head.
I'll bet what is happening is that as the engine is getting ( overly ) hot ( because it is too lean ), the head expansion is letting air blow past the cylinder head, resulting in the low compression.
Get the engine to the point it does this then tighten down the cap screws.
It's normal to have to do this after the first few flights. The cap screws get VERY loose at first.
Its not warm, its hot, sufficiently hot to burn your fingers when you try to choke. At that time there is no resisteance. I did tighten the head screws when I got the black oil. But I did that when it was cold. Any tighter will either strip the threads or slip the head bolt. This is not a new engine, must have already a couple of gallons through it.
The factory set for the HSN is 1.5 turns out or so. We rere running at 2-2.25 turns out. I was watching out to prevent it from running too lean. It goes out with a nice smoke trail
ORIGINAL: opjose
Which may mean you are burning too much oil, though some black oil in the exhaust is not unusual dependant upon the fuel you use.
What are you using? Synthetic or Castor?
For a couple of weeks I was using plain castor because synthetic wasnt available. When flying last year, I was using Klotz 200 plain synthetic. This last weeks I was using klotz 100 which contains 20% castor blend. I have mainly used klotz based synthetic fuel all the time, used plain castor only one week
ORIGINAL: opjose
A 13x6 on a .55 AX seems a bit big to me. I run 13x6's on higher power .75 2C engines. My .61's use 12x6 props.
Step the prop size down to what is recommended until you've resolved ALL problems.
The manual recommends 12x8 or 13x6. I broke-in with a 12x8 but I cant hover with it. Then I moved to a 13x4 and was using it for the longest time. This past week, someone suggested that the 13x4 may be causing over-revving so I put in a 13x6 purely as an experiment. They are all MAS
ORIGINAL: opjose
While it is very likely running too lean, or leaning out in flight, it does not sound like the cylinder is seizing because of the heat.
Again check your cap screws when the engine is hot, all of them, but particularly the head screws.
Also did you rebuild the head at some point?
Is it possible you put things back together incorrectly?
Havent touched anything other than tightening it
ORIGINAL: opjose
Famous words often spoken right before a crash... you MAY have but never assume so until the problems are gone.
Another famous line is ''Watch this!''.... crash...
Safe flying here. I wont test out any fancy moves unless having tested on the sim first and then will do them at good height
ORIGINAL: opjose
Until you've discovered the problem, introducing a new one ( e.g. a new engine ) may just make things worst.
The AX is a good engine and should not give you these problems unless something is amiss.
BTW: Look for nipples that have broken. Remove the nipples clean them and put a bit of thread lock on before re-installing.
Be VERY careful not to overtighten. They go on snug, but they strip very easily.
Also check the muffler nipple. Often it can become clogged with sludge, killing tank pressure and causing what you are seeing.
I had removed the carb a couple of weeks back and cleaned by blowing through the nipples. I used a tubing to blow through the nipple under plain alcohol. Then I removed the HSN and pushed the tubing into the hole and blew through that as well
ORIGINAL: opjose
Put a smaller prop on the .55 AX. This will reduce the load and the heat build up. You may simply be running it too hot.
I use a laser temperature guage to make sure I'm not overloading my engines.
If the temp climbs above 310 degrees around the plug after WOT for 5 minutes, I KNOW I'm either running the engine rich or with too much load.
I will try out the screw tightening bit, will just heat the head with a hair drier and then tighten. I will give it another last chance this sunday as one of the more experienced members on the field has offered to help me out to try and resolve the problem. I am sufficiently frustrated anyeay [:@][:@] If not, I will replace the engine
Ameyam