Piston Problems 
When stripping down the engine I broke a couple of rings on the first piston. I got a set of rings (Sparex) to fit on the number one piston with the idea of measuring all the gaps etc and comparing against my other three pistons to decide whether they need replacing or not.
Unfortunately I've come up against a number of issues...

First question: How should the number four oil ring be fitted?
The originals are all a sandwich of two thin rings and one wiggly one.
The Sparex one has three thin rings!

Second question: Why is there a lug in the fifth ring groove? It stops the ring fitting - it's not possible to compress it enough to fit into the liner.

Third issue: one of my pistons is not the same as the other three!
Number one piston has the lower oil ring groove, the other three are the original type.

Final problem: The top groove appears to be wider than the ring, with a thinner and deeper groove at its centre. When in this inner groove the ring compresses right down so should fit into the liner, however when loosening the compressing tool to slide the piston down it jumps up out of the inner groove and sits on the lip. The ring then is sat on this larger diameter part and can't be compressed enough to push down into the liner.

I've sliced one finger tip open already so am calling it a night now!

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