09/18/2026
Poetry Kevin I stole a ton of technology from my Ducati race bikes that helped my vintage bikes win tons of championships. To began with piston coatings in the early 90’s and progressed from there. Thank you 🙏 sharing
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This shot of a 2004 Honda CRF250R four-stroke 250cc motocross piston shows important details of the underside. We see that the two skirts and the two wristpin bosses are joined into a single box by the curved struts between them.
We can see that the wristpin bosses flow upward into the piston crown via smoothly radiused curved surfaces.
You can also see that the piston crown is thinner than the height of the piston ring belt.
You can also see that the designer no longer fears that piston crown heat, flowing into the wristpin bosses, will cook the lubricant out from between pin and bosses, and between pin and connecting-rod small-end bushing (if any).
One of the problems possible in these areas is wristpin scuffing – the local micro-welding and pick-up of metal from the pin bosses. In the case of Pankl rods in the race version of Ducati’s 916, a Packard-like drilling was run up the rod to carry lubricant to the small-end bearing and nearby pin bosses. Piston cooling oil jets have made this kind of complexity unnecessary.
You will notice that this piston has smooth, flowing organic shape. This is the kind of shape that best survives the intense fatigue environment of a piston, starting and stopping twice per revolution at literally thousands of Gs. No wonder race engines have a parts-change list, enumerating the high-stress parts and indicating the hours-of-service at which each must be changed.
The grace of natural forms, such as the way a tree trunk flares out to become the many roots, or the manner in which branches join the trunk, is the product of millions of years of testing. The forms that survive are beautiful.
Photo: Honda