912UL runs hot?

[turboturner]

Good point Greg - check each cyl individually. I'll do that later in June when I return. Ref your question: dry powdery soot on the tip & electrode of # 2 but wet threads on that plug (?), dry white plug on # 4.

[Danzer1]

On #2 can you tell if the wet thread is oil, fuel or coolant? May not be a carb problem - could be rings on #2. Or if the carb is set to rich, you could have excess fuel in #2 and #4 could be lean for a different issue - maybe valves. Is it dropping any fluid levels at all? Are you sure you have consistent, strong spark at all cylinders. How may hours since cylinder inspection? Could be due for a look see - spark, valves, cylinders, rings! If your cht's and egt's are vastly different between 2 & 4, you likely need to look inside.

Greg

[turboturner]

smart questions Greg. Fluid levels are steady & the latest compression checks (over a year old) were good (130 on # 2 & 132 on # 4). When I "leaned" out the left carb ( 1 1/4 turn open vs 1 1/2) the plugs on # 4 responded immediately - they were white after one hop, but the "wetness" on the plugs in # 2 was gone (still covered in black soot). So it seems that # 2 is getting more petrol than it needs but the "metering" screw at the carb is doing its job. As you suggested earlier I'll connect a CHT on each cyl, in turn, & get their readings. I suspect # 2 to run cooler than 4. It'll be interesting to see by what difference, and then decide the next course... Could this all be because of a weak coil? I'll be comparing the resistance of all four too.

Thnx again.
Carl

[Danzer1]

Doubtful it would be a coil (but possible), more likely could be plug wires though - I'd check the resistance on each while you're doing it. The temps will tell you a lot - so you know where to head. I'm also assuming all 4 plugs are identical and properly gapped?

Greg