A new way to stop piston Slap

[Milan]

Quote from FB user:

Have you considered knurling the pistons, it leaves tiny cross hatch groves that is good for oil retention and slightly increases the diameter

M

[m in sc]

absolutely not. hack repair. 

[Hawaii-Mike]

Somebody on one of the triples forums said this works: https://swaintech.com/race-coatings/race-coating-descriptions/piston-skirts/

[Milan]

Ya.
Posted as a Joke, to get people riled up

M

[rodneya]

Used to be pretty common back in the day as a way to reuse worn pistons. I have even seen shims sold to be used in worn ring grooves. Although why you would not just re bore and replace with new I dont know.
Not really the best idea on a two stroke.

[1976RD400C]

Back in the 70's I worked at a machine shop and we knurled pistons and cut worn ring grooves wider on pistons and installed steel spacer shims. I can only remember doing a few and they were antique engines and maybe some lawn mover type engines. There was a special machine to do the piston skirt knurling and it made a perfect cross hatch, not like that piston picture. The old timer that ran the place said it did help with oil retention. Never was there any talk about doing it to a 2 stroke. I remember we honed a lot of rods and pistons to fit +.003" piston pins when they had wear and machined heads to fit new valve guides and seats.

[sav0r]

The piston in the picture isn't a knurl. My best guess is that it is a device for holding oil or reducing surface area. The space is negative on a regular piston surface, and that isn't how you knurl something. A neat looking setup though, and with the flexure it is curious indeed.