3 lean or one rich?

[JETmachine]

The C 0-200 has 68 HSOH. At the 100hr inspection Leak-down check:
#1. 90/100
#2 90/100
#3 90/100
#4 90/100
These are the bottom plugs.
#1-normal
#2-rich
#3&#4-typical bottom plug oil trace w/normal coloration
What makes #2 rich?

jt

 

[reileyr]