Greetings,
I recall reading that on the 2200A, the left side cylinders 2 & 4, tend to run hotter that 3 & 4 as that side runs leaner. That was confirmed by routine spark plug checks with very light tan deposits as removed from 2 & 4. The spark plugs on #3 & #4 have a normal brownish color. After completing a leak down test of all cylinders, #2 failed with a PSI ratio of 80/50 with a noticeable air sound emanating from the exhaust pipe. The head was removed for inspection and it was found that #2 intake and exhaust valves are leaking at the seats. As I thought the condition of #2 would most likely be the same on #4 cylinder, I removed the head off of #4 and found it full of deposits similar to #2, some carbon and the rest of this tan material. I attached an image of the piston and cylinder. I'm guessing that the tan material is lead but not sure. The engine is a Gen 1, serial 22A981 with 201.5 TT. Were there any modifications to the intake side of the carburetor to address the imbalanced mixture? I've seen what are called "Cobra" pieces attached to the carburetor but I believe that is only to address installations with cramped conditions in the engine compartment. And I did rotate the bottom of the carburetor toward 2 &4 but that doesn't seem to help. CHT on 2 & 4 are between 300 - 350 F and EGT between 1300 - 1350F with #4 reaching 1400 on climb out and lowering when leveled out. Thanks in advance!
Alex R.
1400F on climb out is more than is ideal. The maximum we recommend, at full power, for your engine is 1290F. On many installations a 'criss-cross' in the intake helps even the mixture out between cylinders. A 'criss-cross' is basically some vanes inside the intake tube before the carburettor that divide it into quarters.
Also depending on what you coldest egt is on climb out it you can go to a larger main jet to richen the full power.
Thanks for the quick reply! Is this criss cross commercially available? Is there any documentation by Jabiru covering this?
We stock one that has 45 degree curve up. Unfortunately, this is not covered in our documentation. Which seems to be an oversight.
