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Discussion Starter #1
Cold or warm, this engine has a very slow/hesitant throttle. My last bike was an '87 Jawa 350, so I am sort of behind of this modern technology... Is it normal for a Vulcan? Or for Vulcan 500? Or something is wrong with this particular bike? It has only 1k miles, so I assume it sat a lot... Many thanks for any ideas!
 

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My last bike was an '87 Jawa 350, so I am sort of behind of this modern technology...
'08 EN500 are still carbureted. Hard to know what you mean by hesitant. My bike does hesitate a little, but it is so slight that I don't notice it at all when riding. I really have to be feeling for the delay in order to notice it. This is my first carbureted vehicle ever (so I am sort of behind on this older technology :p), so I just just figured it was a carburetor thing! My car has a drive-by-wire... now that has a very noticeable delay, the thing feels like a death trap.

If it is really bothering you, then there might be an issue.
 

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Discussion Starter #4
'08 EN500 are still carbureted.
That is one of the reasons why I like this bike!

Hard to know what you mean by hesitant.
By hesitation I mean a situation when I accelerate, but nothing happens, RPMs simply do not increase, and 2-3 seconds later the engine suddenly picks up. I took the bike for another spin later today, and I think I figured out what's going on. I noticed that the sound from the muffler on the left is different, or better to say, there is no sound at all from the right. When the engine kicks in (what I earlier called 'hesitation'), it is in fact the other cylinder simply starts running. I am not surprised since this 2008 bike has only 1,200 miles on it. Anyway, I'll wait for a while, see how it goes, and if this problem stays, I'll clean and sync the carbs. That's the plan for now.
 

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That is one of the reasons why I like this bike!


By hesitation I mean a situation when I accelerate, but nothing happens, RPMs simply do not increase, and 2-3 seconds later the engine suddenly picks up. I took the bike for another spin later today, and I think I figured out what's going on. I noticed that the sound from the muffler on the left is different, or better to say, there is no sound at all from the right. When the engine kicks in (what I earlier called 'hesitation'), it is in fact the other cylinder simply starts running. I am not surprised since this 2008 bike has only 1,200 miles on it. Anyway, I'll wait for a while, see how it goes, and if this problem stays, I'll clean and sync the carbs. That's the plan for now.
Try some SEaFoam It may save pulling the carbs. :)
 

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Is the left cylinder running at idle? Maybe the idle screw is completely screwed in? A lot easier to check than pulling the carbs!
 

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That is one of the reasons why I like this bike!


By hesitation I mean a situation when I accelerate, but nothing happens, RPMs simply do not increase, and 2-3 seconds later the engine suddenly picks up. I took the bike for another spin later today, and I think I figured out what's going on. I noticed that the sound from the muffler on the left is different, or better to say, there is no sound at all from the right. When the engine kicks in (what I earlier called 'hesitation'), it is in fact the other cylinder simply starts running. I am not surprised since this 2008 bike has only 1,200 miles on it. Anyway, I'll wait for a while, see how it goes, and if this problem stays, I'll clean and sync the carbs. That's the plan for now.
I would pull the spark plugs and compare the two. The color on the plug is indicative of the most current conditions so if they look normal or same during idle, you may want to ride the bike on the road/highway (take a spark plug wrench) and while at speed pull the clutch in and hit the emergency shutoff switch while riding onto a safe shoulder. Brake to a stop and check the plugs then (take a pic while at it). The colors on the plugs will show the condition currently (whether the bike is running lean, rich, or normal).

I've never worked on a dual carb bike so can't say if it's a synchronization thing or a dirty carb.
 

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I second trying some Seafoam...it may very well help.
Just follow the instructions on bottle...no more than an ounce or two per gallon.
 

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Discussion Starter #9
Is the left cylinder running at idle? Maybe the idle screw is completely screwed in? A lot easier to check than pulling the carbs!
Yes, both cylinders run. The idle screw is somewhere in the middle. I reied to adjust it after a 15 minute ride and left in a position when the engine was idling at about 800 rpm (to my ear).
 

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Discussion Starter #10
Pulled out the plugs

Thanks everybody for ideas! I put about 5 oz of seafoam into a full tank and pulled out the plugs. They look identical, so I assume there is no problems with syncronization? Other than that they look crappy - wet and black on the insulator and around, some yellow-greenish residue on the very top (looking upside down). What could that be?
 

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From my understanding:

White soot = lean
Black *dry* soot = rich
Black *wet* residue = oil in chamber

I'll be honest... my EN500 is the fist carbureted engine I have ever own (excluding lawn equipment), so please do some of your own checking too.

Are these new plugs? If they are old plugs then you really have no reference as to when they were fouled. I might be temped to get a few new plugs and drive them and then read them. This will give you a better idea as to what is going on inside the cylinders now. From my understanding, plug reading really only works at WOT. But if your plugs are fouled, tuning might be a little difficult.
 

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Discussion Starter #12
From my understanding:

White soot = lean
Black *dry* soot = rich
Black *wet* residue = oil in chamber

I'll be honest... my EN500 is the fist carbureted engine I have ever own (excluding lawn equipment), so please do some of your own checking too.

Are these new plugs? If they are old plugs then you really have no reference as to when they were fouled. I might be temped to get a few new plugs and drive them and then read them. This will give you a better idea as to what is going on inside the cylinders now. From my understanding, plug reading really only works at WOT. But if your plugs are fouled, tuning might be a little difficult.
Thank you, I have ordered the plugs already. Sorry for the ignorance, what is WOT?
 

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The old school technique is to run the engine WOT, cut the ignition and pull the plugs right on the spot. This gives an accurate "reading" of how the engine was running under load.

Before you fiddle with the carb settings, make sure there are no leaks around the intake boots, airbox and the air filter foam seal is good. These engines run somewhat lean from the factory, so counterinuitively, they need a specific amount of intake restriction to run right. Any leak will take the mixture over the edge from "lean" to "too lean". Ashy white or yellow deposits on the plugs are a sign of lean burning. Clogged fuel delivery will also cause a lean condition and terrible performance. Finally, pay attention to the fuel vent tube on the carbs. It's T connector that appears to go nowhere. It must be facing back towards the rear of the bike.

The youngest Vulcan 500 is now 12 years old. Clogged carb passages are a prime culprit (the air filter foam seal is probably dust too). Seafoam is a "hail Mary" approach that can sometimes save you from having to clean and rebuild the carbs. Honestly though, I've found that Techron does a much better job. Seafoam is essentially light oil, a mild solvent and alcohol. Techron is a true detergent. Either way, use the correct amount/ratio for the Vulcan's tiny tank, run the engine to get the fresh fuel in the carbs and let it sit for a while.

You can siphon a strong Techron/gas mixture directly into the carbs and run the engine to get it into the passages, but do not ride the bike with an overly strong mix of Techron or any detergent additive in the tank. It can quite literally wipe away the protective oil layer from the cylinder wall.

http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm
 

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Setting the pilot mixture "in about the middle" is not good enough.
Set to factory specifications and then tell us how it runs.
 

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"One sign of heat used by some professionals is electrode color. Many--but not all--spark-plug electrodes have an alloy composition that will oxidize green when subjected to high temperatures (see Photo 2, again). This nickel oxide on the center wire and sidewire would show up first at the tip of the electrode--the hottest part--and progress from there, depending on temperature. Excessive green oxide may signal it's time to change to a colder plug. Several causes of high spark-plug temperature are described in the boxed information at left. The main thing to keep in mind here is that not all electrodes oxidize (turn green) at the same rate, if at all. Therefore, your best bet is to turn to a technician with experience reading plugs."

From http://grounds-mag.com/mag/grounds_maintenance_servicing_spark_plugs/

Hot condition is caused by running the wrong plugs or running the engine too lean.
 
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