Popping back through the carb

[excess11]

I have a 78' XS1100 standard. The bike has started popping back through the second card on the left. It will pop about every 5 seconds with no regular pattern. I was syncronizing the carbs when it started to pop. It would send a blue flame about 10" up the tube of the synchronizer every time it would pop. It has not stopped popping since it started. I need some help with this one. I have no ideas! Thanks!

[ratbyk]

Back Fire

Back firing out through the carb usually indicates a lean mixture. If it started all of a sudden the first thing I would check would be the rubber manifold for cracks, loose clamp retaining carb to manifold, manifold to head gasket/sealant.
Spray the area with engine running with WD 40. Listen for a change in idle speed as the oil momentarily plugs the vacuum leak. Watch to see where the oil is being drawn into the intake system.
Some people use starter fluid (ether) but it can be dangerous, if it back fires while doing the test. (eats eye brows and lashes)
Ken/Sooke.

[skids]

Re: Popping back through the carb

Synching the carbs should be done at about idle speed. If you did this and there are no leaks through the boots or around them, and your pipes and exhaust gaskets are in good shape, and the engine was well warmed-up, you might try turning out the pilot screw about a quarter turn to richen it a bit...

Originally posted by excess11
I have a 78' XS1100 standard. The bike has started popping back through the second card on the left. It will pop about every 5 seconds with no regular pattern. I was syncronizing the carbs when it started to pop. It would send a blue flame about 10" up the tube of the synchronizer every time it would pop. It has not stopped popping since it started. I need some help with this one. I have no ideas! Thanks!

[excess11]

Found the problem

I found what the problem is, my plug wires are so bad that they are jumping fire. I seperated all of the wires so that they are not touching each other and the popping stopped. Need new wires now.