1995 Johnson J150SLEOM;
Location: Colorado (4800 ft altitude);
Cold compression (psi):
1 - 108; 2- 110; 3 - 109; 4 - 108; 5 - 100; 6 - 98.
Hello;
History:
Removed, cleaned, and rebuilt all 6 carbs.
Removed. and cleaned, both throttle bodies.
Since I was this far, I decided to remove both intake manifolds to inspect the reed valves.
Engine was not spitting, but as I have never removed the intakes (owned since new), I figured what the heck.
Upon removal, I immediately noticed the 3 port side crankcase intake openings (where the reed valve assemblies sit) were considerably dirtier than the starboard intake openings.
The starboard side looks almost as clean as new (shiny cast aluminum), but the port side has substantial dark carbon on all cast aluminum surfaces.
Note: the port side has a history of fouling plugs much more often than starboard side.
General question:
What could cause the starboard half of motor to be very clean (internally) and port half to be heavily carbonized?
I have considered the starboard bank of cylinders may be running hotter (more cleaning?) than
the port bank of cylinders, but the engine runs fine at 150F at idle speed. No overheating.
Also, all 6 carb have the same #30 mid-range jets, and 57D high-speed jets.
Any ideas on what could, or could have, caused this?
Note: I am going to decarbonize engine, with a gallon of gas/seafoam mix, at next outing.
Thank you very much in advance for any ideas.
Location: Colorado (4800 ft altitude);
Cold compression (psi):
1 - 108; 2- 110; 3 - 109; 4 - 108; 5 - 100; 6 - 98.
Hello;
History:
Removed, cleaned, and rebuilt all 6 carbs.
Removed. and cleaned, both throttle bodies.
Since I was this far, I decided to remove both intake manifolds to inspect the reed valves.
Engine was not spitting, but as I have never removed the intakes (owned since new), I figured what the heck.
Upon removal, I immediately noticed the 3 port side crankcase intake openings (where the reed valve assemblies sit) were considerably dirtier than the starboard intake openings.
The starboard side looks almost as clean as new (shiny cast aluminum), but the port side has substantial dark carbon on all cast aluminum surfaces.
Note: the port side has a history of fouling plugs much more often than starboard side.
General question:
What could cause the starboard half of motor to be very clean (internally) and port half to be heavily carbonized?
I have considered the starboard bank of cylinders may be running hotter (more cleaning?) than
the port bank of cylinders, but the engine runs fine at 150F at idle speed. No overheating.
Also, all 6 carb have the same #30 mid-range jets, and 57D high-speed jets.
Any ideas on what could, or could have, caused this?
Note: I am going to decarbonize engine, with a gallon of gas/seafoam mix, at next outing.
Thank you very much in advance for any ideas.
