Admittedly, this is not a GS500 question.  My wife's Vulcan started running poorly yesterday on the way home from a two-day ride (600km).

Today when she was getting ready for work it backfired and wouldn't idle without the choke on.  Even with the choke on it was running rough and slow.  She took the truck to work instead.

Tonight I pulled the air filter out and it was damp with gasoline.  How the heck does that happen?

Even with the air filter out it's not running right.  Low revs with the choke on and dies with the choke off.

Nothing's changed since Saturday.  The bike wasn't down on it's side or anything.  We did fill up with gas on the way home yesterday, but my GS has the same gas in it that hers does.  

Any thoughts would be appreciated.   :dunno:

Vulcan - 750 or 500 or 1500 ... anyway 750 ... very commonly the float gets stuck a sharp tap, or a ride over bumps may clear it out. 500 - presumably the same thing. Keihein crabs ... 1500 - no clue.
Cool.
Srinath.

It's a 2004 Vulcan 500 LTD.  Keihin CVK32 carbs.

So for a stuck float.... whack the side of the carb with a rubber mallet?

OK the best way may be to drain the gas from carb, refill with prime ... might clear up ... Rubber mallet sounds a shade extreme ... but screwdriver handle ... then rubber mallet ... Then sledge hammer ..  :lol:
Cool.
Srinath.

In case anyone was curious...

I removed the air filter, blew off some dust and let the gas dry out of it.  Then we load the bike in the truck and high-tail it down to the dealer.  The service manager takes it for a ride and it appears to run better for him... nice.

He offered the following

- starting the bike with choke and throttle may have caused a backfire, which explains the gas in the oil filter
- you should start a cold bike with choke and NO throttle
- you should start a warm bike with throttle and NO choke

He pulled the spark plugs today and noticed they were both fouled (on a new bike with 6000km on it :dunno: )

He's putting hotter plugs in.

He also suggested my wife might want to give the bike a good run now and then.    :mrgreen:

Hopefully we don't see too many pictures of my GS like this ....

Quote from: daneilah

Tonight I pulled the air filter out and it was damp with gasoline.  How the heck does that happen?

Though there can be other causes (cam timing off), the effect is pretty much the same, and you already know the most likely answer to that.

Quote from: daneilah

Even with the air filter out it's not running right.  Low revs with the choke on and dies with the choke off.

When you remove the air filter and try to start the engine, you have a SERIOUS lean condition, which is a very bad thing. The bike probably SHOULDN'T be able to start with the choke off (unless you've done some carb rejetting), because you have a LOT of air (no restriction from the air filter, which you've removed), and not nearly enough gas to support combustion.

When you put the choke ON, you're essentially DECREASING the amount of air available to the engine (which is WHY it is called a "choke" in the first place) :lol:; that means you have (relatively) MORE fuel to burn compared to the amount of air available, and the engine should at least be able to chug along to some degree. Truthfully, it isn't a nice thing to do to the engine, and you shouldn't do it any longer than absolutely necessary.

We won't go into too much detail about an "enrichening circuit" for now; just understand that it works differently than a choke, but with the same end result. A choke decreases the air flow, while an enrichening circuit increases the amount of gas available to the engine; though I can't explain why, chokes have always seemed simpler to me. Controlling the airflow seems less difficult than finding a way to add even more gasoline under the proper conditions.

Quote from: daneilahAny thoughts would be appreciated.   :dunno:

Gee, I hope you meant that, because I took you seriously... which (I hope) helps explain all the typing...

Quote from: daneilahIn case anyone was curious...

I removed the air filter, blew off some dust and let the gas dry out of it.  Then we load the bike in the truck and high-tail it down to the dealer.  The service manager takes it for a ride and it appears to run better for him... nice.

He offered the following

- starting the bike with choke and throttle may have caused a backfire, which explains the gas in the oil filter
- you should start a cold bike with choke and NO throttle
- you should start a warm bike with throttle and NO choke

He pulled the spark plugs today and noticed they were both fouled (on a new bike with 6000km on it :dunno: )

He's putting hotter plugs in.

He also suggested my wife might want to give the bike a good run now and then.    :mrgreen:

Hope you don't mind a few more comments...

1.  Logically, the service manager is correct; a backfire will spit the fuel back through the carb, into the air filter. His recommendations for starting a motorcycle are also correct; if you remember the olden days, when starting your NON-fuel injected car (unless the car had a problem), you didn't usually have to pump the hell out of the gas pedal while you were starting it, did you? When the engine was cold, you most likely just stepped on the gas pedal once, to set the choke, and then turned the key. When the engine was hot, you probably didn't even have to touch the gas pedal; you simply turned the key, and the car started. The same principle applies to your NON-fuel injected motorcycle; you want to use one device (choke) or the other (throttle), depending on conditions, not both at the same time. When you combine the use of the choke and the throttle, you're restricting the amount of air available (making the fuel/air mixture rich with the choke), and making it SUPER-rich by adding fuel with the throttle, a sure-fire way to foul spark plugs.

2.  Plugs can foul for many reasons; old gas, bad gas, oil in the gas, water in the gas, and dozens more. Don't laugh; there is ALWAYS some water in the bottom of your gas tank, from simple condensation. Think about it; the gas tank heats up during the day, just from the presence of sunlight, and when the tank cools down at night, condensation forms on the INSIDE of the tank, then trickles down into the fuel, and eventually settles to the bottom of the tank, because water is heavier than gas. Of course, that helps explain the reason for the notorious rusted-out crap pockets on the GS5 gas tanks.

One basic way to reduce the amount of condensation that occurs in your tank is to simply keep the tank full of gas. The less air space there is inside the tank, the less room there is for condensation to form.

The good news is, you can add a little Dri-Gas to the fuel tank on occasion. The alcohol in the Dri-Gas will mix with the water in the gas, and that will make the water at least semi-combustible. Every time you gas up, the new gas shooting into the tank mixes everything together, and until the water in the tank has time to settle to the bottom again, you're actually burning slightly diluted gasoline.

I've run motorcycles down to Reserve before, then drained the tank into a clear glass bottle. After a while, the crud and sediment from the tank begins to settle to the bottom of the bottle, and it is easy to see the gas floating on top of the water. As you can guess, that's another good reason to clean the screen on your fuel petcock occasionally; it gives you an opportunity to drain and flush the gas tank, so you can monitor the tank crud / rust / sludge / water situation.

Plugs also foul from a lot of stop-and-go riding, extended riding at low speed (AKA just putting around), and short rides. That is why the service manager suggested "a good run now and then"; he wants someone to just get out and make an extended blast down the freeway, which will get the plugs up to operating temperature, and burn off some of the accumulated crud. Of course, that won't really help if you have to lug then engine at ~40 MPH for twenty minutes once you leave the freeway; the plugs will just load up with crud again.

Let me know if this makes sense (or not); I've been up all night again, and I'm not sure my brain actually works now...

Sweet.... thanks for the thoughts.  

We got the bike back Saturday and it's seems to be running well now.  We'll have to see if it fouls up in another few thousand km's again.     Hopefully changes in her starting/riding habits (plus the hotter plugs) will keep the crud at bay.

Glad to know your wife is back on the road; please keep us posted on this. Good luck to both of you; ride safely.

I dont know if this really helps any.. but if your bike is running a tad rich (or the choke is on) its fairly common for some backflow to spit gas onto your airfilter.. actualy.. I have a buddie with a harley.. and it never stops spitting a pinch of gas from the carb to the air filter (its been piped and jetted a little too rich) and yes... no airfilter and or the choke on while you ride is not a good idea.. you probaobly fouled your plugs running with the choke on (I've left mine on by accident before) and with the plugs fouled you need more fuel to burn because your plugs are having trouble igniting the gas... sorry if I read the question wrong... or if I reposted someone else's answer.. but I just skimmed the posts.. got a new puppy last night and I'm trying to keep an eye on him  :lol: