Ran into an interesting case, 2005 J115PLSOR, 60 degree V-4 2-stroke looper, aftermarket cylinder head gauge showing temps separately for port and starboard.
At WOT, port bank runs about 30F cooler (120 vs. 150F). Has anyone seen this?
What I know so far:
1. Probably real - heat cam confirms, gauge calibrates correctly.
2. Probably not one cylinder dead - starts and fires with any three cylinders disconnected, heat cam shows uniformly cooler head.
3. Probably not ignition - new coils and powerpack: replaced as a result of an earlier incident, spark looks good.
4. Probably not thermostats - swapped between banks, same picture.
5. Power loss - maybe. Fails to get to full RPM, but that may be an unresolved trim issue.
Less than 10 hours after break-in on a new powerhead, compression good across the board, carbs redone at that time, new Boyesen reeds.
Another observation: if I throttle up to 2000 rpm and just let it sit there, both banks warm up to 140F, and then port temperature drops.
What am I missing here, and do I panic yet?
Thanks!
At WOT, port bank runs about 30F cooler (120 vs. 150F). Has anyone seen this?
What I know so far:
1. Probably real - heat cam confirms, gauge calibrates correctly.
2. Probably not one cylinder dead - starts and fires with any three cylinders disconnected, heat cam shows uniformly cooler head.
3. Probably not ignition - new coils and powerpack: replaced as a result of an earlier incident, spark looks good.
4. Probably not thermostats - swapped between banks, same picture.
5. Power loss - maybe. Fails to get to full RPM, but that may be an unresolved trim issue.
Less than 10 hours after break-in on a new powerhead, compression good across the board, carbs redone at that time, new Boyesen reeds.
Another observation: if I throttle up to 2000 rpm and just let it sit there, both banks warm up to 140F, and then port temperature drops.
What am I missing here, and do I panic yet?
Thanks!
