When I was younger me and a mate used to build rat bikes,( really bad survival bikes) we would look about for bikes that where either free or came with much cheapness, one day we picked up an xs250 that needed pretty much everything but could be made to look whole with an exhaust/handlebars and a tank. We got a tank from the scrappies and but a set of old bars from the parts bin but we did,nt have an exhaust, the exhaust that was on the bike was shredded and really only the core was intact, whilst having a lengthy 30 second think about it I came apon the idea that a Heinz baked bean can was really just the same as a silencer, and that with my fabulous fabricating skills I could make a new silencer out of the can, this was done and fitted to the bike in under 1 hour,(we had to have beans on toast to get rid of the evidence) one of the things we had not realised though was that the exhaust was VERY loud, another brain storming session and it was agreed that some form of packing was needed, as packing is really just steel wool
I instructed my mate to just whip it off and put some in, some hours later sitting having a relaxing evening with the GF the door go's and low and behold its the mate looking quite upset and smelling like a chemical fire, it seems that he had but Brilo pads in the exhaust,(these are those steel wool pads that are impregnated with soap and used for cleaning dirty pots n pans), he had taken the bike out for a test ride when a guy on a beemer passed him pointing at his head and making the universal nutcase sign then pointing at the rear of the bike, when the mate looked behind him he said there was a 10 foot flame coming from the exhaust, he stopped and tried to put the flames out with his quality bike gloves,(cheap and nasty ski gloves) these having a burning napalm like substance went up as well, now that was 25 years ago and he still has the gloves as a reminder that there is no substitute for good quality bike gloves.
P.S. his hands where fine and we got the bike quicky style into a van and down to his parents garage, so if your where riding a K series up laurestan place in Edinburgh all those years ago....it wisnae me.