I pulled apart an engine looking for bits for Link and found these.
The grooves on the pistons are the first I've seen. I don't know who or I don't know why. Probably to hold oil and reduce seizures. I've seen pin holes in various places on the skirt for this reason, I'm not certain or convinced of their need or success. I would rather better porting and reasonable tuning (rather than last poofteenth 'on the limit' optimistic tuning).
Anyone know of them or heard of the practice? I would be very suss about weakening of the piston!!!
"A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." - George Fitch Atlanta Constitution, 1916
Agreed it's probably for oil retention. But a good bore will have crosshatch for that anyway.
Looks to me like there is evidence of minor seizure even with their fancy grooves.
Nothing is going to stop a seizure if it's too lean or runs out of oil anyway.
