Should I replace Pistons rings

[tico70]

Hello

My Sidekick 92 (1.6L( JX was smoking a little bit, so I decided to check the cylinder head. Before I unmounted the head, I did a compression and a leakdown test.

these are the readings for the compression (5000 ft Altitude):

Dry:

Piston#1 : 155

Piston #2 : 155

Piston#3:155

Piston#4: 155


WET:

Piston #1 : 170

Piston #2: 170

Piston# 3: 175

Piston#4: 175

Leakdown

Piston#1 : 30% lost (hiss sound between Piston#1 and 2)
Piston#2: 10 %
Piston#3: 5%
Piston#4 10%


I removed the head ( I am going to rebuild the head), pistons shown carbon build up on top of pistons and valves.


The cylinders do not show any ridge at all. I did a quick measurement for the cylinder bore using telescopic gage

Piston#1 top: 74.95mm, Bottom: 74.97

Piston#2 Top: 74.97mm, Bottom: 74.93

Piston#3: top: 74.97mm, Bottom 74.99

Piston#4 Top: 74.96 mm, Bottom: 74.96 mm


Question: Can I replace the rings only.? If I replace the pistons rings, it will increase or improve the compression? Does it worth it?

According the bore readings, it seems that pistons are Standard (C2 marking on pistons and 2222 on block)


   

   

   

   



Thanks in advance.