Members who have donated towards server costs
Join Date: Nov 2007
Location: Chandler, Arizona
Ok, first, have you had the carbs off? If not, you may need to remove them, and give them a thorough cleaning. But I would try soaking them in Seafoam while still on the bike first. Use only Seafoam, NOT automotive carb cleaner.
What probably happened, is that in 2 months, all the gas evaporated from the float bowls through the vents, allowing the floats to drop all the way down. Since the vacuum operated petcock will not allow more gas to flow into the carbs without the engine running, they sat empty for some time, and the residue from the evaporated gas caused the floats to stick. It also probably partially plugged up the jets. I know for a fact that would happen in 2 months here in AZ. Had it happen to a number of dirt bikes.
Normally I would recommend removing the carbs, taking them apart, and giving everything a good cleaning, just so you know everything in there is ok. But the Vulcan 750 has the hardest carbs to remove of any bike I have ever owned, so trying something else may be worth trying first.
Put the bike on the centerstand, remove the fuel lines form the petcocks, loosen the carb float bowl drain screws and drain out all the gas. Now, using a very small funnel, fill the float bowls full of straight Seafoam through the fuel lines. Turn the engine over with the starter a few times. The engine should fire, though it may not actually run. Do that until smoke comes out the exhaust. Do it both with the throttle closed and completely open. The reason for doing that is to actually suck pure Seafoam up into the jets. Let it sit about 24 hours, drain out the Seafoam, and refill the carbs with gas, and start it up. If it is better, but still not quite right, ride the bike for awhile (if it is rideable) with Seafoam in the gas (you can pour a whole 16 oz can in a full tank of gas without problems) and see if it clears up. If not, it is worth going through the whole soaking procedure at least once more before pulling the carbs.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike