During a recent tranny maintenance I noticed that the fuel line had chaffed through about half its thickness where it emerges from under the airbox. Further inspection showed more chaffing under the airbox itself, with the marks corresponding to the ribs cast into the top of the tranny. The line was from Bing Agency, some of their black alcohol proof stuff, installed after the MOA National in Oregon several years ago. I elected to replace it with a fresh line, also from Bing, but this time in clear (well, it's more of a transparent, uncooked egg white color) but I wanted to be able to see fuel flow so it's good enough. The old line was still flexible, hadn't split, and was not leaking at any of the fittings, and since the new line is made from the same alcohol proof plastic, I figured I'd get the durability of the old line and be able to see through it as well. To prevent, or at least slow down, the chaffing, I covered the portion of the fuel line under the airbox with two layers of electrical shrink tube. This not only provides some protection for the line, but also makes it a much tighter fit under the airbox, which may reduce vibration and hence the chaffing. It's too soon to tell if this strategy will work in the long run, but with a thousand miles on the new set up there are no problems. I also used a burr in a Dremel tool to radius the edges of the airbox and transmission housing where the fuel line emerges from the bike. Now here we are years and tens of thousands of miles down the road, and I can no longer endorse the Bing Agency fuel line. I've found that it gets brittle and the electrical shrink wrap only marginally mitigated the chafing. I've switched to the old school braided cloth covered line as supplied by Ted Porter's Beemer Shop. It's a perfect fit for the fuel tank and carb fittings, when cut with a razor blade the cloth doesn't fray, and it lasts three or four years before the ends loosen up on the fittings. It also looks like it belongs on an airhead.