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Discussion Starter #1
I've been noticing lately that my Vulcan revs down very slowly once the engine is thoroughly warmed up. I was having a problem with the bike not idling well but that seemed to go away after I gave it a heavy dose of Seafoam. The only thing I did (or tried to do) was adjust the throttle cables. Did I adjust the throttle cables wrong or is something else going on?
 

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If it started after you adjusted them I would suspect that first also,The service manual gives a procedure for adjustment,but basically you need to leave a very slight bit of slack in the accelerator cable and the decelerator cable should have no slack.
your throttle should have a little free movement before it starts to move the throttle open,2 to 3mm according to the book.
 

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Discussion Starter #3
I tried to go by the book, but when I tried to twist the adjuster on the throttle, it wasn't rotating, but twisting the entire throttle cable. How do I avoid that? And yes, I did loosen the lock-nuts.

Would my poor adjustment explain the rough idling I experienced too?
 

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I tried to go by the book, but when I tried to twist the adjuster on the throttle, it wasn't rotating, but twisting the entire throttle cable. How do I avoid that? And yes, I did loosen the lock-nuts.

Would my poor adjustment explain the rough idling I experienced too?
only if your idle is set too low to begin with did you try to adjust it with the black knob on the left side of the bike .It should be idling around 1000 to 1100 rpm. There is more adjustment at the carb end of the cables besides what is at the throttle but it is a pain to get your mitts in there.If you can get your idle steady,then adjust the throttle cables,Are your fuel screw plugs still in or can you see the screws
?
 

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Discussion Starter #5
Yes I have been adjusting the idle to 1050 like the book suggests. And I'm not exactly sure what you mean by fuel screw plugs. I'll have to check that tomorrow.
 

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Yes I have been adjusting the idle to 1050 like the book suggests. And I'm not exactly sure what you mean by fuel screw plugs. I'll have to check that tomorrow.
That book of Psalms in your tool bag is good to see!
 

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While you are looking, test and make sure your throttle is snapping back to the return all the way. If it is, every time, then it sounds like a vacuum leak that opens up when the engine is warmed up. Have you had the carbs off?

It stands to reason that your cables are not adjusted right, but strange things happen sometimes where a non related item will show up and make you think you did something to cause it. I'm just throwing it out there! ;)
 

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Check the throttle, both cables, and the linkage on the carburetors. Sometimes things get dried out or corroded. When you open the throttle all the way with the engine off, it should instantly snap closed when you release it. If it doesn't, it is binding or sticking somewhere. The "fuel screw plugs" refers to the lead plugs over the idle air/fuel mixture screws. there is one on each carb. If they are still there, leave them alone for now. The factory setting isn't perfect, but will not cause the kind of problems you are describing. If they are missing, go ahead and remove both screws and springs, spray a little Gumout carb cleaner into where the screws were, then spray WD-40 on the screws, put them back in, turn them until they seat lightly, then back them out about 2 1/2 turns. That is a good starting point. It should run fine there. If both the throttle/cables/linkage and the A/F mixture screws are ok, then start looking for vacuum leaks between the carbs and the engine, or in the carbs themselves. Both carbs have a vacuum fitting on them. Make sure they are not leaking. Don't worry about looking for air leaks between the air filters and carbs right now. While leaks there can let dirt into the engine over time, they will not lean out the air/fuel mixture enough to cause problems. Check that after you get the engine running right. Jerry.
 

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If all else fails, check the diaphrams in the carbs. They may have gotten stretched out or even ripped.
 

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Discussion Starter #10
Ok now that this talk of vacuum problems has come up I suppose it is important to mention that my carbs have been leaking a little fuel. The leak was much more pronounced when I first pulled my bike out of winter storage earlier in the spring, but the leak seems to have gone away since the weather has warmed up. The leak appears to be coming from the gasket between the carburetor body and the cylinder head on the rear cylinder.

Went for a 100+ mile ride today and the bike performed very well, this ride included a hot run through some wonderful twisties in the beautiful Pennsylvania countryside. When I say hot run I mean hard accelerations and higher revs (Never exceeding 7,500 RPM mind you). Everything seemed normal and all the power seemed to be there when it should be. Another thing the bike will do very rarely is miss under acceleration. When it does miss, it will usually only missfire once or twice and then act like normal. I'm assuming that air is getting somewhere it shouldn't?

I frequently check my throttle as part of my pre-ride inspection and have always heard and audible snap coming from the carbs which I'm assuming means the throttle is hitting its stop.

Thank you for all of your help. Do you think a carb overhaul is in order?
 

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Yes, it could also be leaking diaphrams. (I hate CV carbs) The part between the carb and the engine is called the manifold. It is supposed to be air tight, and completely sealed on both ends. If gas is leaking out, air could also leak in. The gas leak could have been caused by sticking floats on needle valves not sealing well, which could have corrected themselves with use. There might still be a small problem, or it might just be leaking gas when the choke is on at startup. But in any event, you have an air leak between at least the rear carburetor and head, which can cause all sorts of running problems. You can tighten the clamps and see if that helps, if not, you will probably have to replace the manifold.


As for the carbs themselves, before pulling them off and taking them apart ( taking them apart is easy, removing and reinstalling them is very tedious), try draining the gas out of them, disconnecting the fuel lines at the petcock, filling the carbs up with Seafoam through the fuel lines, and letting them soak for 24 hours. This might get rid of any remaining gunk in there that could be interfering with the floats, needle valves, and jets. It's worth a shot before pulling the carbs. Jerry.
 

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Discussion Starter #12
Heres an update:

I was riding down the highway with the engine completely up to normal operating temperature, when all of the sudden I started losing power. The Tach started bouncing up and down and the bike was lurching. I immediately took the first exit I could and the problem seemed to go away, it was idling fine too. Later (about ten minutes) I was slowing down to at a stop light when the engine died while it was still at about 2000 RPMs. Also, it is still very slow to lose RPMs if I pull the clutch out as I come up to a stop. The entire ride home the bike was not running right and the tach needle and engine seemed to be all over the place.

I tried looking for the plugs that cover the screws but couldn't seem to find them. What side of the bike are they on exactly?

I hope this helps narrow down my problem. Could it be vapor lock? I did fill up on gas before the engine warmed up.
 

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The tin plugs are from the factory, sealing the air mix screws that are located next to the vacuum ports, one on the outside of each carb. In other words, there's one on the left side of the bike and one on the right, located on the visible side of each carb. If the plugs have been removed, then you'll see the small brass air mix screw ends with a slot in them for a screwdriver to adjust them.

If your tach was bouncing around while the issue showed up, I would check your front coil connections, or your ignition switch for something loose. I don't think the fast idle problem is necessarily related to the stumbling engine issues you experienced in your last post. Hard to say, but I feel like it is two different issues.
 

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Discussion Starter #15
Took my bike to a trusted mechanic. His first diagnosis is that my low idle jet is clogged, which makes perfect sense. When my bike would start acting up, a vacuum was created in the carbs where it shouldn't be which caused my bike to fire on one cylinder. This could explain why my bike would be so slow to drop to idle, why it was sporadic, and why it would lose power at random times.

My mechanic will be pulling the carbs, cleaning them, and checking for other mechanical issues (I'm keeping my fingers crossed lol).

If any of your BS detectors went off on any of this initial diagnosis, please come forward. My mechanic was a certified Car Mechanic but got out of the field because he likes working on bikes much more. He mainly only works on friend's bikes and I have heard outstanding reviews of his abilities. I'll be sure to keep you posted on progress and thank you for all of your help thus far.
 

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I recommend seafoam frequently as a preventative measure.
 

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Discussion Starter #17
Ok, my wrench pulled and cleaned the Carbs and found them to be spotless and in perfect working order. His next suggestion is that it may be by Cam chains. Could my tensioners have crapped out? I do not notice any knocking whatsoever when the bike is running. Could this be that? Or could it be Electrical? My bike has over 25,000 on it, is my stator finally going?
 

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Get a New Wrench that knows what he's doing..........This one is just shooting in the Dark and will have your Bike in More Problems & $$$$$$$$,
And still not have Your Bike Fixed.

Ok, my wrench pulled and cleaned the Carbs and found them to be spotless and in perfect working order. His next suggestion is that it may be by Cam chains. Could my tensioners have crapped out? I do not notice any knocking whatsoever when the bike is running. Could this be that? Or could it be Electrical? My bike has over 25,000 on it, is my stator finally going?
 

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You can do a search for stator test or check here on the forum and get the procedure. Believe it's also in the service manuals.
 

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Discussion Starter #20
Is it very common for the Cam Chain to fail or slip on our bikes?
 
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