if it's not burnin long enough your not rolling it tight enough, and theirs air pockets in your spliff, you gotta really pack the weed down so it's nice and tight, and if that doesn't work add tobacco, cause your weed might be very dry and crunchy, and if that doesnt work, coat your spliffs and blunts with a little billybee honey, and it'll burn for 15-20 min with you just taking little tokes, same high, but more enjoyable than burning a 5 min spliff, you can really kick back and relax and toke.......