1981 535 Virago Help

[jcox310]

I need some help on my 1981 Yamaha Virago 535. I had the carbs rebuilt about 2 mths ago and the bike rode like a dream on the way home. I have not been able to ride it since then due to weather, but made sure to start it once a week and let it run for a little while to keep the carbs good and battery charged. I took it out this weekend and it is running rough, backfiring and turns off when idling but does start back up easily. There is also a sputtering sound and times that sounds like a pop or burst of air in the tank. Any ideas on what to do about this situation is greatly appreciated.

 

[Tidd]

well, if it has been sitting a while and you have been just pulling it out and starting it and nothing else, to me it sounds like it could be bad gas maybe????

[jcox310]

I drained the old gas out and put fresh in, still had the same problem. Is 2 mths long enough for the carbs to get messed up again? I am going to check the plugs today and change in necessary.

[yamaguzzi]

drain the carbs, put a couple of shots of seafoam in the tank,,keep us posted yg

[jcox310]

can you tell me how to drain the carbs, I have the YICS system on my bike if that is relevant. I have the clymer manual but can't really find how to do that with it.

[Tidd]

wow....I would hope not.....not after two months......If you swapped out the gas then....check your filters.....do a tune up and see what happens

[yamaguzzi]

http://www.thevirago.co.uk/viragomicrofiche/tvmicrofichemain.asp?catalog=tvMicroficheXV500k1983SQL&Model=XV500K%201983

j: your carbs are sideways,,with the float bowl on the side....i believe the drain plug is #34 at the bottom on the side of the carb..this micro fiche should give you an idea of what you are looking for...good luck ,,let me know if i can help any further,,yg

[535rider]

This sounds silly but check to be sure your battery is FULLY charged. You have been starting it over for short times, each time draining the battery a bit. My 535 did the same thing and it was because the battery wasn't any good and robbing the system of power. I has to get a boost then I could barely make it home. I put a new battery in and instantly the problem went away. Check that first.

If it is backfiring then it is not getting gas, or not igniting the gas fully so:
If it won't idle smoothly - idle jets are dirty.
If it idles but won't accelerate - check the diaphram in the carb to be sure it is still all in one peice. I have photos of what it should look like here.
viragotips.googlepages.com

--or it is not getting fuel to begin with from the pump

[jmlloar]

The first thing I would do is sell this thing to a museum, Because Yamaha didnt start making these untill 1987.   Be sure of what you have or the info on how to fix it could be way off

[james0007]

I have a 1987 535 virago 17000 miles with almost the same problem back fireing sometimes and when I give it gas and hold the throttle in one place it barely goes then all of a sudden it takes off like a bat out of hell.this happens off an on not constant.I had a shop tune it up cleaned the jets new plugs new battery new voltage regulator,replaced 1 new slider for the carb which is also the diaphragm,ever time they add these parts it works good for 2 days then back to the back fireing and spuddering again off and on.the shop I ve taken it too thinks it electrical but up to this point they still don t know what it is.starting to cost me alot of money.on that year of bike shouldn t be that hard to find the problem, it not like it s one of these new bikes that are all computerized.since they tuned it up and done everything they ve done it runs really good when it aint back fireing and spuddering this really sucks because it s the wheels I have to get around