by Dr Z » Fri May 19, 2023 8:42 am
I bought my 2018 300 with almost 60 hours on it and just got it back together last weekend. 179 hours on stock piston and it needed it, even though it ran fine. It runs like new now. Measure the cylinder and check the stamping inside the cover. Mine was an A cylinder and I put a B piston in based on the measurements. I used Pro-X just because Rocky Mountain had it in stock at a decent price. The directions said it should have .05 to .08mm clearance. The manual says .1mm is the upper limit. Get the squish tool also as you will need to set the base gasket thickness.
2018 300RR, SC2 Smart carb, Recluse Radius CX and left hand rear brake, IMS oversize tank, Seat Concepts low seat, rear Tubliss, oil injection deleted.