I've recently purchased a gs that sat for a while with the carbs off. i've put everyhting back together and attemptted starting with no luck, took the carbs off and cleaned them( not that dirty at all). After attempting starting again the carbs are getting blown off the engine and the engine is backfireing. could this be a compresion problem? or is it somethng else? the bike has about 15k miles and wasn't taken good care of. the gas is good but it the bike will not start. any advise?
It sounds like the cam timing is off. The intake valve is open when it trys to fire, so it blows out the intake port.
Take the cam cover off and check the cam chain tension. If that seems ok, Then use a 19mm wrench on the ignition rotor to rotate the motor. With the tdc mark on the rotor lined up with the ignition pickup on the upper right side.Check the cam timing marks. The slot on the end of each cam should be facing straight across at each other. Intake cam slot facing forward O-
exhaust facing back -O. If they seem ok it might be something keeping the intake valves from seating, Like rust or something.
Put your palm over the carb manifold and seal it. Then turn the motor over and see if you feel it blow past the valve.
Gino's bike was doing this... turned out to be defective spark plugs... brand new defective NGK's... Still have them, they seem to get better when you toast them in the exhaust or a candle ... so they have some soot on them, but once they get some heat and that cleans off, its back to running like shaZam!...
Cool.
Srinath.