How often should I replace EC300 piston rings? Every 15 hours? 50 hrs? '11 EC300 with S3 High-compression head insert. Rebuilt top-end 10.2 tach hours ago. Inspection: the piston and cylinder showed no noticeable wear. Conrod big end/crankshaft, no vertical play. User Manual (pg 17) states: Change/Replace every 3 fill-ups (* only if it is necessary). 3 tank fill-ups is about 15 tach-hours. Pre-Mix Ratio: I've found a 32:1 rather than the Factory 50:1 ratio seems to make more power, and possibly less wear, Clutch issues: Catastrophic clutch basket failure. Replaced with Barnett Clutch Basket. See photo.for broken pieces and wear on clutch basket base (not ears). GoFasters commented that this was common with the OEM clutch basket. Note: OEM Clutch Basket Cushions are not compatible with Barnett or Rekluse Clutch Baskets. Barnett clutch basket cushions are only available from Barnett. Kickstart Ratchet Pinion Spring: Replaced. The spring looses tension over time, resulting in the ratchet pinion not engaging consistently. Also replaced kickstart spring and bushing. GoFasters comment that the Kickstart Ratchet Pinion on older models (Pre '07) were made from a softer material resulting in premature wear; and confirmed that the Kickstart Ratchet Pinion Spring looses tension over time.