Motorcycle Repair: 1981 Yamaha Virago VX750 Backfire & Sputtering, transistor ignition, float bowls

Question
I just got my bike out of storage and it is now backfiring and sputtering between 1800 and 3000 RPM.  This happens after the bike has been warmed up with the choke in any position.  Late last year (October) I had the carburetor tuned, spark plugs replaced, and an over all tune up.  I am at my whits end because this is my first bike and I have only been able to ride it 5 times.  Any help would be much appreciated.

Thanks

Answer
Matt,

try filling the carb float bowls with some
good yamaha carb cleaner and let
them soak overnight.

It only takes a few weeks for
fuel to go bad and plug up carb jets
while sitting. You have to use
a fuel stablizer when parking a bike
for any length of time.

Another cause of these older Yamaha
running poorly is the TCI or
transistor ignition module.
The solder seems to loosen up
from vibration over time.
Check here for the symptoms
and other info:

http://members.aol.com/ddenowh/TCI/index.html

Try cooling the module with an ice pack
and see if it helps.
It is mounted under the fuel tank.

Check the side stand switch for bad
connection. Check that battery cables
are tight and check
all ignition connectors and frame ground wires.

You might want to check the spark plug
caps resistance also. (5000 ohms)
Ignition coil: primary 2.7 ohms / secondary 8500 ohms
Pickup coils: Double: 125-185 ohms / Single:180-222 ohms.