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I bought a 1986 Vulcan 750 (14,000 miles) from a repair shop that sells used bikes about six months ago and it has been great for the most part. The bike has been ridden less than 1,000 miles since I bought it since I mainly use it for short commute trips. I'm having an issue now and want to try and diagnose and repair it myself since that's the best way to learn.

The bike starts fine with strong ignition after a couple turnovers. It also idles fine with or without the choke open and the rpms increase with increased throttle. But when I pull in the clutch and put it in first I can already hear the engine is not firing as strong. If I try to ride somewhere the engine just putters out in ~1min. It will restart quickly with no problems, but it will quickly putter out.

I've checked a few things...
-It has gas
-The spark plugs look in pretty good shape

I'm thinking I need to check the amperage going to the spark plugs to make sure the spark is strong enough. Any other ideas or recommendations out there?

Thanks!
 

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Being that the bike is 24yrs. old and such low milage, you can almost bet the farm that the fuel system needs a good cleaning, including tank, petcock, fuel lines, and carbs.
It sounds like it is starving for fuel, so that is a good place to start.
Leave the ignition system alone for now.
 

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sfair is probably right about the whole fuel system needing a thorough cleaning. But as the engine ran well for a thousand miles in the past six months you have been riding it, I have a suggestion.

Before pulling the tank and carbs off, try pouring about half a can of Seafoam fuel conditioner/cleaner into a full tank of fresh gas. Start the bike and let it run for 5-10 minutes so the carb bowls can fill with the treated fuel. It may dissolve any gum or varnish without having to remove anything. Let the bike sit for a day or two then start it up and see if it runs any better.

Always try the quick, easy and cheaper way first. :) The stuff can always come off for cleaning later if needed.

Just for giggles check the battery voltage.
It is at least 12.5 volts with the engine off isn`t it?
And 14 V plus or minus at 4-5K rpm.
 

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Seafoam can work in some instances, but it is also myopic. It cannot see diaphragm rubbers that are torn or holed, O rings that have gone hard, viton needle tips that are grooved. After 24 years, it probably is time to give those carbs an inspection and freshening. At least, that is what I would do, whether the Seafoam works, or not.
 

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Seafoam can work in some instances, but it is also myopic. It cannot see diaphragm rubbers that are torn or holed, O rings that have gone hard, viton needle tips that are grooved. After 24 years, it probably is time to give those carbs an inspection and freshening. At least, that is what I would do, whether the Seafoam works, or not.
I agree with all you say. I`m just saying maybe he can get it running well enough to finish the season. Then the tank, petcock and carbs can come off for a good cleaning and rebuild when it is too cold to ride.
 

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Maybe?

Guess you need to find out first if it is fuel or an electrical problem. By what you say, I think it might be either. Search me for a post I just replied to for electrical info on mine cutting out etc..
BTW, with that low miles on yours, you should not need a rebuild unless it has run low of oil or some such abuse. I suspect a fuel or electrical myself.
'Tis easy to take the petcocks off and blow them out and dump the gas in the tank out in something clean and see if you have any gunk or rust etc.. Will only take a half hour or so, then you can relax if that is all it is. I also put aftermarket filters in my fuel lines going to the carbs. Also bypassed and removed the Vapor rig for CA emissions I was having trouble with in case you have that also? Like mentioned before, I would try this fuel thing first.
Good luck and let us know what you find.
Good Luck :D
TC
Vulcan 750cc 1989
 
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