i just brought my brothers bike yesterday and i noticed that whenever i rev it it back fires 4 or 5 times is this normal or is there something wrong with the bike????
hey mate i have had the same problem with my bike it was backfiring heaps and i looked at the inlet manifold (the pipe that goes from the carb to the engine) and the gasket had blowen. Its no problem though go to super cheap or autobarn etc.. and buy some gasket paper (my dad got gasket paper from his work but u should be able to get some from supercheap or autobarn) and just make ur own gasket also use gasket glue to make it stick as well. also upgrage the bolts to allen key bolts because u can get them much tighter and use locktight.
as jazle said check the inlet seals maybe the bolts are a little loose if not check the exhaust where it connects to the the engine cause i know that if there loose an the exhaust isnt tight on the engine it can back fire when you declerating