Backfiring
 

Hi All,
I bought myself a Carson Stormracer for Xmas and its been working fine. Recently I bought a new glow plug (Mtronics quickfire), when I fitted it the engine started ok, but when I reved up it backfired and blew the seal between the engine and exhaust I replaced the seal and now it barely starts at all and when I rev it backfires. I'm afraid to start it now in case I break it.
Help (new and confused)