I used the small clear line for the impulse. I know I've seen where others suggested the Echo black line.
And there's a bigger hole with a plug in it straight behind the the impulse tube on the carb if I ever need to go back with a larger o.d. line. But the small line let me run it through the bottom hole, and hook it to the carb before bolting down and route it around inside the airbox. Also, that's what I had on hand.
I'm hoping I have all those vent line pieces on the 3800 parts saw, that I'm stealing the top end off of for the 3400.
Will have to take a look tomorrow.
Need to round up some 1/8" i.d. fuel line that's thicker on the outside to fit the hole in the tank.