can any one help my gpz 500s backires on start up,

i tried setting the timing as shown in the hanyes manual but it dont have anything in there about the back firing.

my bike had been standing for a bout 3 years before i got her and had a second engine i did get her started but since then all i get now is the back fire

maxine bolesworth, August 2009

Start and run engine for 1-2 mins. If it wont actually run yet, keep spinning engine over for 30 seconds.Switch off and check if air filter is wet or smells strongly of petrol.If it does, and considering the bike has been standing for three years, it's possible the carbs may be "gunked up" with old fuel,which means they will need removing,stripping, cleaning and reassembling. Refit then balance with vacuum gauge.

VL1500 TONY, August 2009

I'm not trying to be patronising here, but you haven't got the plug leads swapped over, have you?

John, August 2009