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Discussion Starter · #1 ·
I am reaching the end of my rope trying to figure out what is wrong with my 1996 Vulcan 1500 (VN1500). It started 2 weeks ago. I was riding to work and right before I got there I decided to fill up at a Shell station since I was on reserve. Filled up with unleaded 91 octane, drove 1 block to work and parked it. After work, I came out and tried to start it but it began to backfire, act like it was out of gas and die at idle. I manage to limp home keeping it revved high and riding through it's lurching and sputtering.

Then the following weekend I started working on it. I first thought the fuel was the culprit so I drained the tank and got gas from a different station. Didn't make any difference. I then tried replacing the fuel and air filters and the spark plugs which were carbon fouled, (covered with black dry powder). The engine ran a little smoother but still back fired when I revved, and idled . I tried riding it like this around the block and it would run fine then act like I was running out of gas and start to die. Then it would roar back to life and start the same cycle over again.

Last night after letting sit for a few days, I decided to burn the gas out of the lines by switching the petcock/fuel valve to "OFF". That way I could work on the rest of the fuel system, (fuel filter, carb, etc.) this weekend.

I did what I normally would with a cold start and pulled out the choke, opened the throttle and started the engine. After a few seconds, I switched the petcock to "OFF" and pushed in the choke. It seemed like it was idling ok so I let it set until the gas runs out. Not only did it keep running for over 15 minutes, but it idled fine too. (Is it suppose to keep running even though it is "OFF"?) I shut it down and now I am totally baffled. Does any one have any ideas what I should try to do next or what components to look at?

One other thing to keep in mind, I bought this bike used this spring and since it seemed to be running fine I've only changed the oil and oil filter, replace the front tire and brakes but have done nothing else to it. Also I don't know if any routine maintenance was been done in the past.
 

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Sounds like one or more carb float valves are not seating. If there's a fuel drain on the carbs, try to drain some out and see if there's specs in the gas. It doesn't take much grime to hold the valve open. A leaking float valve will cause a rich mixture (Black on the plugs).

Unfortunately, the only way to fix it is to remove the carb, clean and replace the float valve. I have "restored" the resilience of the vitron tip by cleaning it with lacquer thinner but this is a temporary fix. The most likely culpret is dirt/particles in the carb. You may have to flush the tank too. Refueling usually stirs up all the junk.
 

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i read your first thread and that brought up a good thought.
you said it seemed to run FINE on the OFF selection, do it again and go for a ride.

let me know what position its actually in (prime,on,reserve) and i can help more. :wink:
 

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Discussion Starter · #4 ·
QKENUF4U said:
i read your first thread and that brought up a good thought.
you said it seemed to run FINE on the OFF selection, do it again and go for a ride.

let me know what position its actually in (prime,on,reserve) and i can help more. :wink:
I did go for a ride with it in the "OFF" position, (it does say on the valve OFF) and was able to ride around for a while without any issues. But I did discover something new.

After I rode for about 15 minutes I got back to my house, put in more gas and switched to the "ON" position. The same coughing and hesitation came back. I thought that maybe it has a problem running when the engine is hot. So I let it sit for a few hours and went over my Clymer manual, (I almost know it by heart at this point). After it cooled I decided to try a spark plug test as outlined in the manual to make sure they were firing.

I removed the first plug and it was coated with black powder, (running to rich and remember I just changed the plugs). So I continued with the test by touching the plug to the heads and cranking the engine. The spark plug hole shot out white smoke at me. Not a little, a lot. I continued to check the other 3 plugs, (which were black and wet, I'm assuming coated with fuel), and 2 of the spark plug holes shot out white smoke too, getting progressively less as I got to the last plug. This whole time the valve was in the "ON" position.

Now from my experience with cars, (which very little seems to apply to motorcycles), I would adjust the mixture screw on the carburetor to fix this. But I can't find any reference to this in the Clymer manual. Nor do I know what caused this imbalance in the first place. So where do I go from here?
 

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pull your fuel line off and see if there is GAS FLOW with the valve on OFF :?: cause thats quit awhile to be riding around on just gas in the bowls of the carbs. (15mins.)
almost sounds like your float height its either to high or you have bad needle/seats in the cars. :?
 

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That puff of smoke is probably raw gas. Sounds to me like your petcock may be messed up. Also the floats in the carb may be hanging. I had an old GL1000 GoldWing that did this. It dumped enough fuel into the cylinders that the motor would not turn over until I pulled the plugs and hit the starter. Raw fuel blew out of the plug holes and after I installed the plugs it fired.
Just to be safe I wouldn't try cranking it up without first pulling a plug from the cylinders and spinning it over. If it gets too much fuel in their and then decides to fire it may do some serious damage to your valves.
Try rebuliding the carb and the maybe replace the petcock and see it that helps. It shouldn't cost much and it's not that difficult if ya take your time. :)
 

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Discussion Starter · #7 ·
shooter said:
That puff of smoke is probably raw gas. Sounds to me like your petcock may be messed up. Also the floats in the carb may be hanging. I had an old GL1000 GoldWing that did this. It dumped enough fuel into the cylinders that the motor would not turn over until I pulled the plugs and hit the starter. Raw fuel blew out of the plug holes and after I installed the plugs it fired.
Just to be safe I wouldn't try cranking it up without first pulling a plug from the cylinders and spinning it over. If it gets too much fuel in their and then decides to fire it may do some serious damage to your valves.
Try rebuliding the carb and the maybe replace the petcock and see it that helps. It shouldn't cost much and it's not that difficult if ya take your time. :)
It looks like I'm going to have to rebuild the carburetor to fix this. Now I'm no stranger to engines, car engines anyway, but the carburetor has been one of those things that I never wanted to mess with.

So that being said, I'm going to start with checking the float level in the carb and fix if necessary. But then what? Since there is no "Carborator Rebuild" section in my Clymer's manual, what do I need to clean, replace or adjust for a rebuild? Also where can I find a rebuild kit for a '96 Vulcan?

I've got a service manual on order to augment the Clymer and I'm very good at following directions. But can you guys give me any other tips to help with the rebuild? Thanks to everyone for their input.
 

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QKENUF4U said:
pull your fuel line off and see if there is GAS FLOW with the valve on OFF :?: cause thats quit awhile to be riding around on just gas in the bowls of the carbs. (15mins.)
almost sounds like your float height its either to high or you have bad needle/seats in the cars. :?
figured id ask again. :wink:

dealer should be able to get you a rebuild kit for your bike. might want to check here also. www.denniskirk.com http://www.klsupply.com/
 

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Discussion Starter · #9 ·
Rebuild kits

I checked with my local Kawasaki dealer and denniskirk.com and neither carry a rebuild kit. Does any one know where else to look?
 

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Re: Rebuild kits

Hi,
I had that kind of trouble whit my bike,vulcan 1500 97.It was my air filter,it was due,it was running to rich in gas,just like the choke was on it,there was a little black smoke,when they took the air filter off it was ok.So the dealer took a ride whit it and it was fine.He show me the difference between a new one and the old one.You see it in the weight.

Regards
 

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Discussion Starter · #11 ·
Up to speed

Some times the simplest answer is the correct one. It was the petcock. I replaced the old one with one from Ron Ayers, (took forever to get it buy the way), and it started running like it did before.

With it off I was able to blow into the incomming lines of the old petcock with the switch on "OFF"and feel air comming through the out going line. But not as much as when it is in the "ON" or "RES" positions. (And to clear up past questions, the new one does say "OFF" and air, or fuel, can not go through in that postion) When I switched the two she sounded like she did when I first got her.

It still seems like it's running a little rich but but it's no longer stalling and sputtering. I still more than likely need to fine tune the float but I can save that battle for anouther day. I've gotta ride while there is still a few days in the season left.

Thanks for everyone's help!
 

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QKENUF4U said:
QKENUF4U said:
pull your fuel line off and see if there is GAS FLOW with the valve on OFF :?: cause thats quit awhile to be riding around on just gas in the bowls of the carbs.
now you understand why i ask you this 2-3 times. :lol: glad ya got it figured out. dont hold the petcock taking a long time to get to you against RON AYERS , its a great company and he may have had to wait on the factory to get it to him. :wink:
 
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