backfire problem

[cormz211]

hey guys have a 79 gs 550 that has sat for about 6 months now. finally tried starting it again the other day and although it took me a while to start it it eventually starting running. after about 30 seconds it stalled. when i tried starting it again there was gunshot noise from the back and my father said flames as well...i huge backfire. not sure what it can be and it has only happened from the right side, not from the left. any advice is greatly appreciated since its my first bike and dont have alot of experience trouble shooting problems like this. thanks again

[koolaid_kid]

That usually occurs when a mouse family decides to live in one of your exhaust pipes. A large flame is usually the daddy mouse, a small poof is usually a baby.

[koolaid_kid]

Or you need to do a bit of carb cleaning. Your choice.
Did you empty the fuel bowls before setting up? Put Stabil in the tank?

[cormz211]

yes i cleaned the carbs and am currently doing it a second time but did not put any stabil in the tank think that could make that much of a difference?

[koolaid_kid]

Well, your fuel is old, but it should still run. It is either the carbs or the ignition. For sitting that period of time it is usually the carbs.
You need a VM carb person to chime in, I only know CV carbs (80 and later).
You might also take a gander at the points to see if they are sparking.

[cormz211]

it was brand new gas had just filled up a can that morning and poured it into the bike...

[tom203]

it was brand new gas had just filled up a can that morning and poured it into the bike...

If one or more cylinders weren't firing correctly (electrical or carb issue), they would push raw gas down into exhaust- if this unburned (and real fresh) stuff met up with the hot exhaust gas of a functioning cylinder, it would ignite. Probably some maintanance to catch up on- unless you know/trust PO, best to assume it needs attention.