ms391 ring size?

[KZ1000]

I don't have any info covering the ms391, but in looking , I see 47 and 49mm pistons. Did the saw get changed at some time or is one a big bore after market? Thanks!

 

[DND 9000]

The 47 mm piston is used on the MS 311 and the 49mm is used on the MS 391.

 

[KZ1000]

Thanks, get's confusing on the newer ones, don't have the specs for them.