not sure about the "ART" stamping on the piston... I do know Yamaha stamps the piston size in the crown head, but am unsure if Honda does the same. I usually size pistons using a digital micrometer readings below the rings and at the skirt. Hope this helps, danWI
my Tech Data sheet states Bore & Stroke 64 x 50.6mm and Displacement 325cc (a whopping 19.8cu.in!!). when you mic the piston, you should get such results as 64.25mm (1st os), 64.50mm (2nd os), 64.75mm (3rd os)... not sure if Honda offers a 350 1mm over piston!
A forum community dedicated to Honda Twin cylinder motorcycle owners and enthusiasts. Come join the discussion about performance, engine builds, classifieds, modifications, troubleshooting, maintenance, and more!