Usually it's done by hand with a striping brush.I'm bad at it.Some use striping tape but it's kind of cheezy looking for this job.Works fine for a 2 tone that the end of the tape is up under the tank or to the bottom edge of the rear fender.You can also tape out the stripe and spray it or drag a brush over it.Anothet thing you can do is lay down the stripe color first and tape it out,spray the ground coat(black in this case) then flame it.It's a pain this way because there's one more coat of paint and the edge gets thick.It's also best to pull the tape after the ground coat.Then retape it before the flames but instead of taping right back on the edge stay back just a BCH so the flame color will color the black edge-by BCH I mean just a fine sliver of the stripe color showing.The only problem with this technique is filling the stripe with clear to lose the edge and level it.I figure every 1.5 coats of base needs 1 coat of high solids clear to lose the edge,plus the normal 2 you'd use to clear it (3 base to 2 clear).The last thing you want to do is break through the edge or have it so thin it buffs through or a reclear wrinkles the thin spot.That's a guestimate though,and if I'm getting nervous I stop shy of level and reclear it with 2 more.Then block it again and buff.