1 ROUGH IGNITION - RUN UP

11/07/21 – 

• I checked all the spark plug caps and they were secure. I then removed NGK plugs, wiped down, re-gaped to 0.025, re-installed, and torqued all 8 to 20nm. (NOTE Plugs 1 & 2 (4 front plugs) appeared they have been running rich as they were pretty black. They weren’t wet.
• Upon run-up at +/- 4000 RPMs had same issues as below.
• Let set for about an hour, re-started and performed run-up without an issue.
• Just flew in the pattern with no issue.

11/13/21 –

• Upon Run Up at +/4000 RPM
  
  • This time the “R” position ran smooth but the “L” ran rough. On both, it sounded good.
  • I tried several Run ups, still with rough running on the “L” and noticed the RPM drops ranged each time between about 80 to 130 RPMs. All in range by the book but normally my drops are usually around 120 RPMs each
  • I taxied to the other end of Runway and performed another Run Up. This time “R”, “L”, & Both all ran smooth.
  • I did not fly.

NOTE: The plugs were replaced new approximately 25 hours ago. I currently have about 199 hours TT on Engine and Plane.

I’m now concerned about the safety of flying even though it cleares eventually.

Any advice would be greatly appreciated.