I've been using 5/32 tygon line for my vent lines for a few years now. That stuff fits the vent lines perfect. No need for clamps, zip ties or anything. It's a little pricy but stays soft and pliable for way longer than other fuel tubing I've used. It's kinda hard to find in a brick and mortar store, a good hardware store or hobby shops that have large scale gas models will have it for sale usually in dubro packaging. The stock yamaha stuff is metric ... I believe 5mm
