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Let me begin by apologizing for the long post.

I have been having issues with my '96 Vulcan 800 and I am starting to run out of ideas.

About a two months ago running on the highway at speeds between70-75 mph the bike would start to buck and jerk and actually cut off. I thought it may be trash in the carburetor so I tried running seafoam after several fill ups. The bike did run better but it did not fix my problem. After doing some research I attributed this problem to the hypercharger that was on my bike when I bought it.

I replaced the hypercharger with the stock air cleaner and went out of town for a week.

When I returned the garage smelled like gas and there was dripping from the rear cylinder exhaust. After some more investigation I discovered my fuel petcock had failed and was dripping fuel constantly.

I removed the petcock cleaned it and stopped the leak and changed the oil and filter. I have not had any problem since so I believe the carburetor floats were not the source of the fuel leak.

Rode the bike Saturday and it did perfect at 70 mph.

Sunday the bike ran fine until speeds b/t 75-80 and it started to buck and hesitate, this time however it did not try to cut off and I was able to let off the throttle and keep going.

I am not sure if this sounds like trash in the carburetor since I do not have any problems any other times only when I am running at highway speeds and it seems to be better with the stock air filter. I am also not sure if this could be a clutch issue that was partially resolved with fresh oil.

If you have any ideas I am open to suggestions.

I would like to resolve this problem since it is not a good feeling when you loose power and the bike cuts off on the interstate with an 18-wheeler behind you.
 

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Labia Grappler
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Let me begin by apologizing for the long post.

I have been having issues with my '96 Vulcan 800 and I am starting to run out of ideas.

About a two months ago running on the highway at speeds between70-75 mph the bike would start to buck and jerk and actually cut off. I thought it may be trash in the carburetor so I tried running seafoam after several fill ups. The bike did run better but it did not fix my problem. After doing some research I attributed this problem to the hypercharger that was on my bike when I bought it.

I replaced the hypercharger with the stock air cleaner and went out of town for a week.

When I returned the garage smelled like gas and there was dripping from the rear cylinder exhaust. After some more investigation I discovered my fuel petcock had failed and was dripping fuel constantly.

I removed the petcock cleaned it and stopped the leak and changed the oil and filter. I have not had any problem since so I believe the carburetor floats were not the source of the fuel leak.

Rode the bike Saturday and it did perfect at 70 mph.

Sunday the bike ran fine until speeds b/t 75-80 and it started to buck and hesitate, this time however it did not try to cut off and I was able to let off the throttle and keep going.

I am not sure if this sounds like trash in the carburetor since I do not have any problems any other times only when I am running at highway speeds and it seems to be better with the stock air filter. I am also not sure if this could be a clutch issue that was partially resolved with fresh oil.

If you have any ideas I am open to suggestions.

I would like to resolve this problem since it is not a good feeling when you loose power and the bike cuts off on the interstate with an 18-wheeler behind you.
Sounds like it could potentially be the fuel pump going bad.
 

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Three components in firing an engine

There are three components in getting an engine to run properly, fuel/air mixture, compression, and ignition.

Check your fuel pump for volume and pressure like speedeemn says. If it is OK, you have most of the fuel/air problems sorted out, leaving compression and ignition as likely suspects. If the engine fires good cold, compression is probably OK. Check your plugs. A cracked or burnt out plug can cause high speed misfires and stalling as well. If it was running too lean due to the hypercharger, the tips of the plugs could be burnt off. People adding hyperchargers usually rejet the carb, but your bike's previous owner may have skipped a step.
Older bikes (carbs and fuelies) were set up to run rich mixtures to get better performance, up until about 2004
I pulled a couple of manuals for my bikes to see how much fuel needs to be delivered. My 2000 cc has a fuel pump that makes 45psi and delivers about 2 liters (roughly 2 quarts) of fuel per minute. My 900cc has a fuel pump that makes 45 psi and delivers about 1.5 liters or quarts per minute. Both are fuel injected engines. The manual for the 1500 (carbed) doesn't have flow and pressure specs. Sorry.
 

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Got lime? I do
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there are also the problems of safety switches.

it's prolly the fuel pump. but you asked for any ideas.

my RR did the bucking and shit at speed, mostly on the interstate.

mine was the damned side stand safety switch. drove me nutz!

your bike may/may not have this. idk
 

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I experienced the same problem with my 2005 Vulcan 800 Classic. It is equipped with a carb. Runs great up to 60 mph, then past this the engine would suddenly start to die like it was starving for fuel. Twist the throttle sharply a couple of times and it comes to life again. One mechanic suggests the Pet Cock valve, but even when I turn the valve to Prime, it still would cut out. I have done two things so far: stayed with premium gas and changed to NGK iridium spark plugs. I have only reached the 65-70 mph range one time and in cooler weather, but I have not had the engine cut out during this one time. Most of the riding has been done at 60 and under since I replaced the plugs. I'll dismantle the pet cock valve once the snow flies with the prospect of replacing it. Apparently you cannot replace the internal parts of the pet cock valve from what I have learned so far.
 

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Following up on the engine cut-out issue. I have not had one recurring engine-cut out since I replaced the plugs with the NGK Iridium spark plugs while continuing to use the Premium 91 Octane fuel. I have reached the speed several times in which the engine cut-out occurs since my last posting and nary a cough. Smooth sailing all the way. Don't think I'll be pulling the petcock valve off any time soon since it's already -7° C and having to remove snow with the snow blower. Can hardly wait for warmer, dryer weather already.
 

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Engine Cut out Issue.

I had this issue once and the problem was with the petcock switch. The gaskets were ate up, leaks and flooded my engine and crankcase with gas while parked. After an oil change and replacement of the petcock assembly, I removed the EPA component in the same circuit and reattached the hoses. My fuel mileage went up to 53 mpg depending on how much I mash the throttle. Running premium gas is just waste of your money. Your engine is designed to run on regular gas. The rear cyclinder always run hotter than the front so use a hotter sparkplug on it (use NGK CR6 instead of NGK CR7E).

Tygh
 

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The petcock is vacum controled and shouldn't pass any fuel unless the engine is turni

It's possible that you seldom use reserve, and the surface against the rubber seal has began to pit or corrode. The same thing happened to my 99 and fuel was actually pouring from my exhaust and from around my front sprocket.
The petcock is vacum controled and shouldn't pass any fuel unless the engine is turning. I had recently switched over to reserve (which I seldom ever do, always watching my odometer) and the rubber seal/plunger had stuck to the surface of the petcock allowing fuel to flow freely passed it and into the carb, eventually filling my entire block. This was noticed while trying to start it after sitting for a couple of cold rainy weeks. (lucky there was no boomboom)
Before this I had noticed some coughing, hesitation, and stalling while riding, and had assumed it was from bad gas.
I took my petcock apart, and sanded the surface meeting the seal/plunger with some fine sand paper and then cleaned it with some carb cleaner. I then drained the block of the gasoline oil mixture, replaced the oil and filter, and rode for a few days before changing it again to prevent any damage to my clutch and seals. Luckily I've had no more problems concerning the matter.
Hope this information is helpfull!!

Let me begin by apologizing for the long post.

I have been having issues with my '96 Vulcan 800 and I am starting to run out of ideas.

About a two months ago running on the highway at speeds between70-75 mph the bike would start to buck and jerk and actually cut off. I thought it may be trash in the carburetor so I tried running seafoam after several fill ups. The bike did run better but it did not fix my problem. After doing some research I attributed this problem to the hypercharger that was on my bike when I bought it.

I replaced the hypercharger with the stock air cleaner and went out of town for a week.

When I returned the garage smelled like gas and there was dripping from the rear cylinder exhaust. After some more investigation I discovered my fuel petcock had failed and was dripping fuel constantly.

I removed the petcock cleaned it and stopped the leak and changed the oil and filter. I have not had any problem since so I believe the carburetor floats were not the source of the fuel leak.

Rode the bike Saturday and it did perfect at 70 mph.

Sunday the bike ran fine until speeds b/t 75-80 and it started to buck and hesitate, this time however it did not try to cut off and I was able to let off the throttle and keep going.

I am not sure if this sounds like trash in the carburetor since I do not have any problems any other times only when I am running at highway speeds and it seems to be better with the stock air filter. I am also not sure if this could be a clutch issue that was partially resolved with fresh oil.

If you have any ideas I am open to suggestions.

I would like to resolve this problem since it is not a good feeling when you loose power and the bike cuts off on the interstate with an 18-wheeler behind you.
 

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Following up again after having driven over 20,000 kilometers with the Iradium CR7EIX spark plugs. The engine has performed flawlessly. I'm averaging 59 mpg (imperial gallons).
The only other adjustment I had to make early this spring was the height of the carb float. I had some serious flooding after riding on a couple of hot days and a lot of gasoline fumes filling my nostrils before I made the float adjustment. It runs like a top and no more gas fumes. It's a fun bike to ride.
 

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To address the gasoline octane requirements, the Owner's Manual VN800-B10 on page 133 states that the minimum octane to use on my machine is 91. I'm going to assume that there is a reason for this and therefore, I will continue to use the 91 octane fuel. As with other engines, makes and models, I'm sure that the manufacturers would specify the minimum octane the engines are designed for and 89 octane is all they would likely need.

I had serious issues that went away as soon as I replaced the plugs; the engine purrs with the new iridium plugs and the 91 octane fuel. I'm at 34,000+ Kilometers, smiling and counting. I put in 84 kilometers yesterday, 18 March 2011 in 10 degree Celsius weather (50 degree F).
 

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Maybe check before you post.

It would be helpful if people who don't know anything about a particular bike would refrain from answering questions about that bike. Several posters have suggested that paedward05's problem is the fuel pump on his 800 Vulcan. The 800 Vulcan has no fuel pump.
 

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Your problem could be many things, but, considering that you go for quite a while before symptoms arise I would venture a guess that one issue my be a sticky anti back flow valve in you gas cap. I have had issue with mine (vn1500 classic) right after filling the tank to the top or into neck. The sloshing will wet the silicone flap valves and make them sticky, especially if additives have been used in gas. To test for this, open the cap next time it happens and if it suddenly clears up, you will know.
I literally removed mine as they got to be too much of a problem, the only time they come in handy is if the bike is tipped over on side. They otherwise do nothing.
If that is not it, then you will have to progress further into system. It may be that it is not fuel related at all ! But, you mentioned gas in exhaust pipe ! If your petcock is leaking then it would be up to the float and needle to stop flow when carb is full. This would mean that you have a bad float or more likely a bad needle or seat, which would mean crap in carb, which would lead to crap further into the works of carb ! What gets me is that the overflow tube should be running gas well before it goes through the head, valves, Cly,and exhaust. If this happens then you could easily run into a hydraulic lock, and damage something seriously.
Keep looking and leave nothing unchecked. it could be more serious than a wast of gas !
 

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I've been having problems with my Vulcan 800 1997 when I try to start the bike its fine then shift into first and try to let off the clutch and no matter how much throttle it will die out but then shift it from neutral to first a few times and eventually it will go then its gotten worse to when I'm riding and try to take off at a good rate it will slip and have to let off the throttle now I had the same type of fuel leaking problems when the bike was off and I put in a turn shut off valve for the fuel I turn off every time the bike is off any suggestions please ? I don't want to buy a clutch or transmission for no reason
 

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Mine did the same thing backfire and stall under power, thought it was from winter fuel in tank. Drained and refilled fuel with sea foam added. Still the same. Found spark plugs were loose, not even torqued down at all. Replaced plugs, snugged them down tight=problem solved!!
 

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He mentioned he had an Hypercharger and retrofit the factory air filter (...) so if it has been re-jetted for the Hypercharger, now it's probably too rich for the factory filter settings (calibration)... Just an opinion.

I'm riding my '97 800B for 23 years, 'had it re-jetted after replacing factory exhaust by Cobra SlashCut, minor mods in carburator (cut float spring to shorten it by at least 25%), OEM air filter assembly with K&N filter inside. NEVER had any issue with it, this bike is so reliable. Twist the throttle and enjoy. I've raced a lot of other bikes and always jumped in front even bigger ones like 1100 Honda Shadow & Yam V-Star. Just bought a '08 Nomad as "upgrade" but keeping my ol' ladie as she always served me well
 
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