Motorcycle Repair: backfiring thru pipes, rich mixture, tailpipes

Question
i have a 1981 sportie that lost all power and was back firing out the tailpipes. we have checked the plugs and timing and battery what could it be?

Answer
Hi Sandy.
 Did you check the valve gap and timing?  Also make sure that the bike is not running rich due to a clogged air filter.

The battery will never be the reason for a backfire.  It is always due, primarily, to one or more of a few things.

1)  Ignition timing.

2)  Fuel buildup in the cylinder due to rich mixture. Many causes for that.

3)  Valve gap and timing.

Start with those and let me know what you find.
Good luck.
FALCON