hi riding along today the sportster started to misfire so i took it home, got the plus out they where matt black so wire brushed em up put em back in, it wouoldnt start just turn over i turned it for approx 10 secs then gave up, as i let go of the starter there was a loud pop and a 'mist' out of the air intake area? i was concerned so checked for oil leaks incase i blew something but nothing, so i took the plugs out again, i dont know what the spark should look like but this was a pathetic spark, so ima tryu new plugs on monday, anyone got any advice solutions/???

ty
dan