86 Virago 1100 Sputtering

[Racing1278]

I was on a ride the bike was running fine and then out of no where it would spit and sputter could go full throttle and would not go any faster and was still sputtering and if I am not mistaken would backfire a few times. Shortly after it started it ran fine and then a few miles later the same thing. I changed the plugs and remember it had a fuel filter which I had not changed since I bought on 2000. I did a run the following weekend and it was fine no spit or sputter. Then went on a run and about 80 miles or so it came back, but this time I was able to maintain speed and then it dissappeared again and came back twice during the 105 mile run. The air filter was dirty but not to the point it would totally block out air flow. Any ideas as to what is the cause? Plugs are gapped to approx 28 or so and the are thr BPES7 NGK plugs, I almost always run lucas gas treatment in the gas.Can't tell which cylinder is acting up or if it's both but I am thinking possible rear, It has run fine with no problems since 2000. Any suggestion of help would be appericated. Have another run on Sat and want to fix it before then or I will have to ride and keep my fingers crossed.
Thanks,
Rob
1986 Virago XV1100 w/fuel pump

[Streetmedik]

Have you checked for a vacuum leak? HAve you chedked the condition of the battery? These bikes can act really wierd if the battery is not good. THey are picky about theie electrons.

[mark75]

the TCI is a power glutton, and is not happy unless it's getting all it wants.
check battery with VOM; at least 12.5v - standing, 14v or > @ 3-4K rpm.
if your battery is 2 years or more - replace it (it's prolly near dead)
you can get a cheap small hygrometer @ auto supply (~$5) and check each cell. spec grav 1.28 or correct color balls floating (depends on which h-meter you get)

clean/tighten your battery connections, specially the ground at battery and frame.
clean/tighten connections to TCI (black box attached to rear lower fender).

unscrew your spark plug caps and clip ~ 1/4" off, then screw them back on (making certain the center wire touches the 'screw' in the center of cap)

if you have the caps that come apart (OEM)-
look in the end where the plug goes in, you will see the brass thing has slots for flat screwdriver,
unscrew that - pay attention to the order stuff comes out;
spring, washer, resistor (I think that's right)
replace the resistor with an equal size piece of 10 penny nail or brass rod.

try some Bosch Plats #4037 (WR9LP+) @ 0.028"

let us know what happens.