Dragonfly piston rings

[rogerb]

Which way round does the stepped scraper ring go, step up to piston crown or step down to bottom of piston?

[Kalle]

Hi See general tips below



https://www.thn.nl/en/product-line/piston-rings/piston-ring-types

[EW-Ron]

Rings often have a dot near an end of the ring - to indicate the top or up side.
Nothing of that here ?

An oil scraper (ie lower/lowest) ring would generally have the stepped side facing downwards.
To gather and scrape the oil back downwards towards the sump.

But I personally don't know your ring set.
Nothing in the little instruction sheet that likely came with them ?
Knowing the recommended ring end gap is also vital info.
Too little can cause trouble, and equally so can too much....
Hopethishelps.

[eddie]

As I understand it, stepped rings come in two types - stepped compression and stepped scrapers. Normally, stepped compression rings are fitted as 'ridge dodgers' in worn bores (i.e., with the relief at he top). Stepped scrapers are usually fitted the other way up (relief at the bottom). In the case of the postwar Douglas, the stepped ring is fitted in the second groove, so can't be a 'ridge dodger' - so must be a stepped scraper (especially as it was listed from new - i.e. for an unworn bore).

Hope this helps,
                         Eddie.