My 2003 1100 v star sat for 3 months without starting. I started it and only ran on one cylinder. I removed carbs and cleaned. Now it idles fine but doesn`t want to accellerate. We cleand all jets and passages and checked diaphrams. I need advise on how to synchronize the carbs.

Hello, everyone.
The engine is generally healthy and what bugs me the most, has JUST been overhauled by a good mechanic, which included cleaning the carb, after which it started on 1-3 pulls and ran like magic.
Today I went fishing for the first time after not using the boat for about 3 weeks. The engine started fine (with 2/3 choke), I let it warm up a bit, with little-to-none choke. Idle was a tiny bit rough, but nothing major. When I set it on idle for the first time, it ran for about 3 minutes and died. Since then I could only start it with either choke or some throttle and it'd always die quite soon on idle or close to idle. When I try to start it warm with no choke, it'd sound as if it catches and dies off immediately.
The plugs are 1 month old and adjusted, oil's in order, no detectable problems with the prop or anything else.

I have a suspicion it might be either condensate or some grit in the fuel tank, which was stored in a rather damp place for 3 weeks, half full (although tightly closed). What should I check and is there a way to condition the fuel somehow to remove condensate and clean out eventual b/s from the carb without major mechanical work (I really don't want to pull the boat ashore before autumn)?

Thank you!

Did you line up the stator plate line with the notch on the cases? Sounds like your ignition timing is set a bit retarded. I would pull the side cover off and check the timing marks.

Try some carb. cleaner/ starter fluid on that spark plug right before you try to crank it. If that does it
replace your spark plug.

If the bike ran fine prior to putting it in storage and all you did was drain the fuel and disconnect the battery, its likely moisture ( condensation) developed in the carbs while it sat. this type of thing happens when fuel is drained. Your best bet is to remove the carbs and clean the jets. Its my opinion and experience to put fresh fuel in a bike along with (stable) fuel treatment prior to storing them. With the stable added to the fuel, the fuel will hold good for about 1 year.. Replacing the battery and starting them and letting them warm up to operating temp monthly while in storage is always a good idea..
I hope this helps..

Sounds like it may be drawing air around the intake somewhere. Let it idle and spray around carefully with wd-40 until it speeds up. This will reveal the leak.

You have a gummed up mainjet. Always store a gas engine with Staybul gas additive to avoid this problem in the future. Now, on to the current problem. Since the bike will at least idle your in luck. Just go down to an auto parts store and get a can of Sea Foam. I usually find it at NAPA it's a white can that looks like it came from a gas station in the 1940's Because it did. Mechanics have been useing it for years. Anyway, dump about half the can in the tank with a couple gallons of gas and fire it up. Let it idle a long time. Then start trying to ride it. You may have to let it set over night if it's really gummed up but it will clean it out. Easy fix, and you can leave it in with no problems. Happy motoring.

What is the compression on the cylinder compared to the other cylinders? It should be within 10%. Some causes can be - as you suggested - the valve stem seals. Also, the sleeve could be rusted, as the valves could have been open on that cylinder. Generally speaking, on a 4-cylinder motor 1 cylinder has both its valves closed, 1 has both open, 1 has an inlet valve open and one has an exhaust valve open at any given time. Another possibility is that the valve could be sticky - try Wynn's Valve Ease or a similar product.

Change fuel filter.
fuel pump sounds fine.
Check for kinked or blocked lines.
If it has a fuel recovery cannister service it.