Most skis are about 20', and we usually don't do the vent check-valve line. http://www.seadoowarehouse.com/parts.php?type=year
You can follow to prompts to you year/model & part, Open in own window. Bills86e
6mm = 1/4"
8mm = 5/16"
I use goodyear products Red Stripe USCG black fuel-line on my personal ski's. Napa line & fuelline.biz is good clear or colored raceing line..
yes and no, yes because, all the fittings that the require the 5/16in fuel line, will be a PITA, for the 1/4in to go on,...no because, you get the 1/4in fuel line on, your good.