Pixleyad

I do have the before and after correct. I checked back and forth several times! I heat distribution looks good and not concerned, just an odd pattern to be found in both rear cylinders when not present in front cylinders... 100 hours between inspections - 1050 SMOH vs. 1150 SMOH Only other thought I have is that I've been running long cross countries (4 hours plus) at relatively higher altitudes 10K+ and need to keep mix a bit more rich than normal to prevent roughness at the higher altitudes.

1989 M20J IO-360-A3B6 Noticed an odd pattern after boroscoping cylinders during routine maintenance. Only changes to engine management is setting taxi lean after start and going full rich before takeoff vs. leaving full rich on the ground. Interested in everyone's thoughts.

Does anyone know what this cushion is for? Found it in the baggage compartment of newly purchased J model. Not able to figure out where it goes...

Thank you, all. We ended up rebuilding the left gear. I.e. taking the discs apart and putting it back together. The suspension was then tight and there was no play. I agree it’s getting to be time for the discs (dated 2009). We lowered the jacks and let the gear bear the weight for the night. Next day these was still no play. Looks like I will get another year!

Both left and right main discs measure the same length. The right side has almost no play.

Here's the video! https://www.youtube.com/watch?v=fFGqatA7GQg&feature=youtu.be

It is up/down.

We have confirmed it is one of the interesting hybrid systems. Thank you all for your help!

Recently did a gear swing on 1989 M20J and noticed the Left main has about .5" of play in it. Both sides shock discs are secure and measure the same length. Any ideas on troubleshooting/adjusting the Left main to reduce play?

Thank you. There is a meter there. I believe that is a hobbs meter and not tach.

I'm finalizing the deal on a 1989 M20J and noticed during pre-buy inspection there is no tach meter. Any recommendations to determine engine time without a tach meter?