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Discussion Starter #1
I apologize if this is the wrong forum for this question. I've been having trouble getting the carburetor dialed in on my Vulcan 800. At this point, I'm not sure if my thoughts were correct, or if something else is causing the problem. It's a '99 VN800A with Cobra exhaust.

I did the Russian Wolf EPA mod, and also drilled out the plug covering the air idle mixture screw. I set the mixture to the recommended 2 1/2 turns out. Initially the bike ran great - better than before the mods. Several weeks later, I started it (without the choke), and it idled for a few minutes then died (when I opened the throttle). It wouldn't start up again unless the throttle was held wide open. Even after idling for several minutes, if the throttle was opened too quickly, it would stutter and die. As it idled with the choke, a small amount of black smoke came from the exhaust, and the exhaust had a "musty/gassy" smell. I was also getting a fair amount of gas in the air filter. I figured it was running way too rich, so I attempted to adjust the mixture to lean it out a little. Now it will only start when the choke is all the way out (which it revs extremely high), and as soon as I turn the throttle (even just a little) or push the choke in, it dies.

I'm pretty sure I was turning the screw in the right direction, but there's always the chance that I'm mistaken.
 

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I apologize if this is the wrong forum for this question. I've been having trouble getting the carburetor dialed in on my Vulcan 800. At this point, I'm not sure if my thoughts were correct, or if something else is causing the problem. It's a '99 VN800A with Cobra exhaust.

I did the Russian Wolf EPA mod, and also drilled out the plug covering the air idle mixture screw. I set the mixture to the recommended 2 1/2 turns out. Initially the bike ran great - better than before the mods. Several weeks later, I started it (without the choke), and it idled for a few minutes then died (when I opened the throttle). It wouldn't start up again unless the throttle was held wide open. Even after idling for several minutes, if the throttle was opened too quickly, it would stutter and die. As it idled with the choke, a small amount of black smoke came from the exhaust, and the exhaust had a "musty/gassy" smell. I was also getting a fair amount of gas in the air filter. I figured it was running way too rich, so I attempted to adjust the mixture to lean it out a little. Now it will only start when the choke is all the way out (which it revs extremely high), and as soon as I turn the throttle (even just a little) or push the choke in, it dies.

I'm pretty sure I was turning the screw in the right direction, but there's always the chance that I'm mistaken.
Yes, this is the wrong place....your membership is canceled, jk. The fact that it ran great for several weeks kinda rules out anything that you might have done. I would start from scratch on this one. You might double check your idle mixture and see if it is still 2 1/2 turns out. Maybe the plug was the only thing holding it in there. The black smoke and gassy smell is definitely rich..........more than likely from the choke. After you check the idle mixture, I would make sure that you don't have a vacuum leak. Any troubleshooting will be meaningless if you have one.
 

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Discussion Starter #3
It is still 2 1/2 turns. In fact, I double checked it today. I partially took the carb off today (because that's the only was I can access the screw), screwed it all the way back in, then backed it out 2 1/2 turns. I thought for sure that it would make an improvement, but it seemed to have no effect. I didn't notice any black smoke or gas smells, but it did sputter quite a bit. I don't think there are any vacuum leaks, I think everything is connected as it was before.
 

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Custom '07 1500 Classic
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Check the float needle, sounds like it may have some trash in the bowl causing the needle to stick open resulting in too much fuel. Also you should check your pilot jet and make sure it's not clogged up. One more thing to check, the vent line on left hand side of the carb that runs under the tank needs to vent, it may be plugged or possibly pinched by the seat.
Keep us informed on how it goes...
 

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Check the float needle, sounds like it may have some trash in the bowl causing the needle to stick open resulting in too much fuel. Also you should check your pilot jet and make sure it's not clogged up. One more thing to check, the vent line on left hand side of the carb that runs under the tank needs to vent, it may be plugged or possibly pinched by the seat.
Keep us informed on how it goes...
I agree........especially about the bowl vent. I would check that first (easiest). Keep us posted.
 

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Discussion Starter #6
Thanks. The vent line is not pinched or otherwise obstructed. I'll check into the float needle and the pilot jet, once I figure out which ones those are. Does the carb need to be removed to do any of that?
 

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Rebel Rider
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Make sure the petcock is in the run position and not the prime position. Have you done any mods to the air box?
 

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I had all kindsa problems with my 800a when I did the Scooterizing upgrade. I tried set the A/F screw in all kinds of settings with no real changes. Until I read about putting two #4 washers as shims under the needle to raise it up a bit. That made it run so much better. Is your needle stock or aftermarket??
 

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Need Time To Ride
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Sounds like you need to pull and clean the carbs. Add add an inline fuel filter while you have everything apart. Seems like the float needle isn't sealing or fuel is pulled through the main jet when it should pull through the pilot circuit.
 

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Discussion Starter #14
I had all kindsa problems with my 800a when I did the Scooterizing upgrade. I tried set the A/F screw in all kinds of settings with no real changes. Until I read about putting two #4 washers as shims under the needle to raise it up a bit. That made it run so much better. Is your needle stock or aftermarket??
I haven't Scooterized, just removed the EPA check valve thing. As far as I know, the needle is stock.
 

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Discussion Starter #15
Sounds like you need to pull and clean the carbs. Add add an inline fuel filter while you have everything apart. Seems like the float needle isn't sealing or fuel is pulled through the main jet when it should pull through the pilot circuit.
I don't understand why it would do this all of a sudden if it just needed cleaning. Removing and disassembling the carb is a bit out of my knowledge area/comfort zone, so I'd like to exhaust as many possibilities as possible before removing the carb.
 

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Discussion Starter #16
A picture of the carburetor

The engine was cold and not running. I'm wondering if the slide is supposed to be open the way it is? If not, what could be causing it to stick open and could this be contributing to the problems stated earlier? I had planned on taking the same picture with the engine running for comparison, but the bike decided to not start.

*Caution - it's a large, 10mp file.
 

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Nobody Home
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That looks about right. Really sounds like you got some crud in the float bowl and plugged the pilot jet. It's got a really small hole in it and plugs pretty easy.
 

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Machinist For Sale/Rent
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looks high in the slide to me for not running. Take your finger and push it up to the top of the travel, pull your finger out quickly. Did it return to that exact same point with a "thunk"? If not there is something holding it up. Could easily be a piece of scale or crud from the gas stuck in the main pilot. That is where the needle looking thing goes, down into the pilot.
 

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Can be a few different things, dirt or water in the carb, try draining the carb bowl, I 'd drain the tank too, could be bad gas. Refill with fresh gas and and some seafoam. Also tank petcock could be bad, put on "prime" postion and plug vacuum line to petcock (small hose). When petcock goes bad, gas can get though to vacuum side. Otherwise I'd say there's dirt in carb passages and carb will need to be removed to be cleaned and float valve tip checked, they are known to go bad.
 

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Custom 800
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long time no see bob and cos. glad to see you guys still visit. lol
Hey Cos, What about those RAVENS. Kicked some butt.
Sorry did not mean to hijack just wanting to say hi
 
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