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Discussion Starter #1
Hey folks, so I recently bought an '03 Vulcan that has probably been sitting for 6+ years. PO said he drove the bike from the place he bought it to his house, parked it, and it's been sitting since. Been having issues with it running properly. Once I got a fresh battery in, she started, but wouldnt idle properly and would bog down and die when trying to rev. So I cleaned the carbs, replaced spark plugs, oil, and air filter. This fixed some of the idling issues, but still wouldnt run when at half or no choke. Took her for a couple test rides to see if it would smooth out, had less than 10 miles on it before backfiring and dying. Now it wont start and when I do try to start it, has a clunking sound coming from the right side. Before the most recent test ride, had a hissing almost tick sound in tandem with RPMs that wasnt there before. When riding, throttle was sluggish or even bogged down when trying to speed up at low RPM, often stalling out. When taking turns, wanted to die then as well. I was thinking it's a fuel issue before, but now that it wont start at all, I'm not sure what to do. Probably made it worse by riding it. Any clues?
 

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I'm not a bike mechanic, but I play one on TV. Shame on that guy for buying a bike and then parking it for 6+ years.

Anyway, take the petcock off of the tank and check the two filters for rust. You either have a fuel delivery issue or a air delivery issue. You can clean the carburetors until they look brand new, but if the filters are clogged or the tank has varnish you're just sucking that crap right back into the carbs. When you say you cleaned the carbs, did you take the jets out and clean them? Take the air filter out and clean the filter box. You might have a rat nest in there. Check the vent hole under the gas cap. I would bet that the vent is clogged. When you say it won't start, will it turn over? Or is it completely dead? More info please.
 

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Discussion Starter #3
When I took the carbs out i took out the jets, diaphragm and floats out, scrubbed down all metal parts with carb cleaner, soaked the jets in carb cleaner and used compressed air to clear them out. Only thing I didnt do is take out the pilot jets because I didnt want to have to drill out the plug. Does the plug even serve a purpose? I was thinking that could be it, but I haven't yet because it's such a pain to get the carbs out. I think my next step is to check the air box then. And as far as trying to start, it did at first, but since it last died, it wont crank over even. So I'm not sure if I messed something else up while test riding it
 

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This bike comes with lean mix from factory, and if that plug isn't removed it still runs on leaner side. Drill that plug, its tamper plug so you know when someone tampered with carbs. Pilot screws should be cleaned and readjusted as well as other carb parts. It affects idle and if those pilots screws are clogged, you will have great trouble starting the bike.

And put new plugs, those on the bike are old enough to be replaced and probably failed. No spark - no running engine.
I got failed brand new NGK spark plug after 20 mile ride recently and thought it was something with valves or camchain or whatever it was, bike started bogging and backfiring, RPMs drop and throttle response was terrible, lost power. Luckily I was near home and bike had enough power to ride on one cylinder to get me home. It also had clunking sound on right side when I started it with one failed plug. So I bet you have failed spark plug. Replace 'em, its cheap. And remove idle screw plugs, you will have to adjust those if you want perfect idle and good running bike.

You should also check valve clearances. This is easy, see the sticky thread. Too tight valves are trouble waiting to happen.

One more thing. Check battery connections too. Loose connection or corrosion will gave symptoms similar to those with dirty carbs. Bogging, terrible idle, power loss etc. Also charge the battery, maybe it got discharged so bike won't turn over.

I see you replaced spark plugs. They can fail if get wet from fuel so bike will have trouble running. Check for spark on both plugs and see if one of them failed.

If none of this solves the issue you can try with hand turning the crankshaft to see if something is locked inside engine. On the left engine side cover (alternator cover) remove bigger cap, you will see bolt inside. Use socket and wrench and turn it clockwise. If it turns, engine is fine and you have other issues with battery or loose connection or something. Check these easy things, don't assume the worst happened.

Sorry if text is bit confusing, I'm at work and typed this fast in order to give you some things to check.
 

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In addition to all of the above, check all hoses and carb boots for leaks. There are several vacuum lines that can cause a very rough running condition if they are left disconnected or are cracked. Carb boots get hard with time, so they can be more difficult to install fully.

If none of this solves your issues, we can move around and do further testing.
 

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Discussion Starter #7
After going through and cleaning the carbs again, disassembling and cleaning the petcock, purging the fuel lines, adding brand new 93 octane gas, and checking the spark plugs, I got her running again. As it turned out, at some point, the carbs looked like they fell off the boots. Unfortunately now I have a different issue. Now, I run it about half a mile before i experience some power loss and eventually stalls out. I'm only going maybe 30 through my neighborhood on these test drives and it's on about the third turn where it starts to lose RPM. Maybe battery connection? Every time it stalls, I have to open the choke up for a second and let the RPMs come up before I can knock it down to half choke. Any ideas from the experts?
 

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I suspect that your issue is a fuel delivery problem. Check the fuel flow from the petcock by disconnecting the line going to the carbs, attaching a different hose to the petcock, then direct the flow to a catch bucket. If the fuel begins strong then tapers off check the tank vent by opening the fuel filler cap. If the fuel flow increases you have found the culprit.

I don't know how the 500A model fuel cap is set up but the 500C models can be disassembled and cleaned. There are some small parts and springs that can fly across the room to be careful when disassembling.

Hope this helps.
 

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Discussion Starter #9
BikerBill, I'll try that out today and see if that fixes it. when i drained the tank the other day, it was mostly constant, but did start trickling out and just needed readjusted to get the flow going again. granted there wasnt much left in the tank anyway, so probably not a ton of pressure on the fuel to get out of the tank. I think i am also going to take a look at the battery connection to see if it came loose at some point, or if i installed it incorrectly. Updates to follow
 

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Discussion Starter #10
Looks like i found the culprit. loose battery connection. took her for a test ride this morning with zero problems. thanks everyone for their help and advice!
 
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