Gas in the Vacuum Advance Unit

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woodrock

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Oct 15, 2010
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Location
Divide, CO
I was installing the pulse generator and vacuum advance unit onto the engine case of my '80 GL1100i, and gas dripped out of the hose attached to the vacuum advance. I removed the hose and shook the advance unit, and soaked an entire paper towel with gas. That can’t be right, can it?

The hose from the vacuum advance connects to the intake runner on the #3 carb, so that’s where the fuel is coming from, but for the advance canister to fill up?? Maybe the diaphragm is toast, but when I sucked on the hose (sans fuel), the advance pulled the breaker plate. What's going on?
 
Sounds like #3 carb is flooding or leaking past the float valve. This was noticed after a prolonged sit? Check your oil for the smell of gas. If there is gas in the oil I strongly suggest you change oil and then find/fix the leak. Are you turning the fuel valve off at shut down?
 
slabghost":1mht3lz5 said:
Sounds like #3 carb is flooding or leaking past the float valve. This was noticed after a prolonged sit? Check your oil for the smell of gas. If there is gas in the oil I strongly suggest you change oil and then find/fix the leak. Are you turning the fuel valve off at shut down?

The bike hasn't been sitting long this season, and I do turn the fuel valve off at shut down. I smelled the oil, and didn't detect any gas odor, but the oil only had about 1200 miles on it (pulled the motor for a stator replacement), so I don't know if you'd be able to tell with that few miles. It's probably neither here nor there, but the bike's been running great, and I might not have discovered the gas in the advance issue had it not been for the stator job.

Not sure if the PO turned off the fuel valve at shut down, or how long it sat, possibly with the fuel valve on, before I purchased it (bought it last summer, but didn't run the bike until this year). One thing that might point to the PO leaving the fuel valve on is that the gas in the advance had that old, stale gas smell. Didn't smell fresh. Could leaving the valve on with the motor off allow fuel to enter the advance?
 
I think it could have leached in from a prior job or fuel issue.If it's running right now I'd forget it.
 
Thanks for the input thus far guys, you're reinforcing my feelings about what must have happened. :salute: I was hoping/thinking that this was an old issue that had corrected itself (outside of emptying the vac adv of the old gas). I could envision a slightly stuck needle/seat freeing up after a decent volume of fuel had been run through it. I know I haven't put as much mileage on this season as a lot of members must have, but I managed to get in about 1100 miles so far, and hope to get in some more after this is resolved. The aspens are changing up here in the high country, making for some great riding.

If there was still an overflow from the #3 carb (stuck needle/seat, etc), how would that show up? I pulled the plugs recently, and they all looked a bit rich, but were more or less uniform in all cyls. If there was extra fuel in #3, it seems like it would look different.
 
If there is an overflow of fuel sufficient to fill the vacuum advance. I think you'd have a miss on start up and fuel would almost certainly foul the oil.
 
I've seen that sort of thing before on automotive vacuum advances. Sometimes, it is simply fuel vapors that get trapped in the line, then condensate back into a liquid.
Seems like, on these carbs, in order for raw fuel to get into that line, and all the way up to the advance canister, there would have to be fuel standing in the engine/cylinder, all the way up past the carb throttle plate....
That being said, I'll admit to knowing absolutely NOTHING about 'Wing carb systems! :read:
 
Well, I decided to chalk it all up to an old problem, not worry about it, and button things up from the stator job. Got the engine back in, hooked everything up, and...

In putting the pulse generator back together, I neglected to position the ignition rotor (reluctor) to point at the alignment mark under the centrifugal weights and tighten it down. :doh: Realized something was wrong after the motor kept cranking but not firing, except for catching now and then.

I thought that the engine was going to have to come out again, but it looks like the pulse generator assembly can be reached after the rear wheel and swingarm is removed. Still a bit of a job, but on the bright side, it gives me an opportunity to inspect and lube the swingarm bearings.
 
Oh man that's a bummer.
Something similar happened to me where i could hear the pin tapping.
I don't remember the details but do remember the pin got damaged and I had to use one from a parts bike.
 
yes it was nice to figure out it wasnt a big deal for me ...good luck ...i got quite the ribbing for not tightening the bolt there :shock: :smilie_happy: :mrgreen: fortunitly for me the back wheel and swingarm were already out so it didnt take to long to get back right ..... :builder:

be very careful the pin that gose in the shaft to lock the advancer in place could be out of the shaft now ....mine fell right into my hand ....its in there if its not in the shaft ...i hope you get it as easy as i did and not loose it :mrgreen:
 
Got the rear wheel, swingarm, and pulse generator pulled off the bike today. :Egyptian: I saw two pins as I looked at the pulse generator components. One was on the underside of what I would call the breaker plate (if it had points), and the other is on the shaft coming out of the engine.

Pretty sure the pin that Dan and Joe were referring to is the one on the shaft coming out of the engine. The stubby little bugger seems like it's okay. Would it be loose, or would it just be sheared off if there was something wrong?

DSCF3086.jpg


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shaft-pin.jpg


assembly-pin.jpg
 
dan filipi":3h5309ix said:
The pin on the shaft coming out of the engine is the one I was talking about.

That's what I thought. If there's an issue with that pin, is it that it'll be sheared, or can it be loose? From the pic, does it look about right (length wise, condition wise)?
 
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