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Ok just stripped my ceramic lined Mugello fitted with a patern Suzuki piston and rings by Mitaka, quite surprised to see the ring end gap had gone from 0.38 on both to 0.80 and 0.85 in about 4500 miles. Is this normal? And would I benefit from using a genuine nos piston and rings as are freely available on eBay?

In other words am I going to see less wear by using genuine Suzuki parts ?

Every Mitaka piston I have bought, Yamaha ones though, has come with Japanese Riken rings. I believe they are well regarded. I wouldn’t be surprised if they make the piston rings for Suzuki anyway.

Personally, I’d change the rings at that sort of mileage if the top end was off.

The first set of rings in a ceramic cylinder have a hard time. I usually advise changing them after 500 miles, then the second set can expect to last for the life of the piston. At 4.5k miles I would change the piston regardless. Mitaka pistons are very good, but like owt else, it doesn't pay to tempt providence in these matters.
0.38mm was a big gap to start with. I would have expected a measure of around 0.25 - 0.3mm from new.
What's your piston / bore clearance?

Fast n Furious wrote:What's your piston / bore clearance?

It was .003 of an inch when first done (apparently) I will let you know what it has worn to with the Mitaka piston once I get the cylinder back as I've had to take it to a local machine shop to get the deck height corrected, you see this engine was built by a local "tuner" and I never saw inside until I stripped it down last week and found the squish was 2.2mm! Along with a few other issues I'm not going into here ( for now anyway).

Ideally 2 thou would be best.
I doubt though that you can get a graded Mitaka suzuki piston. It's pot luck if you get the correct clearance with these. You can have more success here using forged equivalents from other manufacturers. You pay a price for these though.
2.2mm........... Oh dear.