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Chasin' the blacktop
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Discussion Starter #1 (Edited)
My '03 Vulcan is a little hard to crank but idles and revs great but as soon as the clutch starts to engage the tack just drops while the bike doesn’t move or barely jerks when the clutch is released. The engine runs great but with no power. It even revs up fast. It started last week in cool weather and at first I thought I was out of gas even though the bike had only run 94 miles since the last filling. I switched to reserve while still rolling but never could get the engine to do more than sputter as I coasted to a stop. It would not restart. Got it started next day but zero power and a few terrific backfires while trying to restart the bike. Removed and drained tank and removed/disassembled petcock, all looks good. Vacuum while hard to read looks around 15 with wildly shaking needle from one cylinder. Other cylinder vacuum the same. Timing light flashing for three of the four wires seems erratic. Plugs look ok but maybe a little rich but after trying the start the engine so much their color probably isn't reliable indicator. Both exhaust pipes feel strong when running although one cylinder’s exhaust is a little cooler to the hand. Money is tight so I don’t want to just swap out the ignition module on a whim but that is my next thought.
Any help would be appreciated.
 

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My '03 Vulcan is a little hard to crank but idles and revs great but as soon as the clutch starts to engage the tack just drops while the bike doesn’t move or barely jerks when the clutch is released. The engine runs great but with no power. It even revs up fast. It started last week in cool weather and at first I thought I was out of gas even though the bike had only run 94 miles since the last filling. I switched to reserve while still rolling but never could get the engine to do more than sputter as I coasted to a stop. It would not restart. Got it started next day but zero power and a few terrific backfires while trying to restart the bike. Removed and drained tank and removed/disassembled petcock, all looks good. Vacuum while hard to read looks around 15 with wildly shaking needle from one cylinder. Other cylinder vacuum the same. Timing light flashing for three of the four wires seems erratic. Plugs look ok but maybe a little rich but after trying the start the engine so much their color probably isn't reliable indicator. Both exhaust pipes feel strong when running although one cylinder’s exhaust is a little cooler to the hand. Money is tight so I don’t want to just swap out the ignition module on a whim but that is my next thought.
Any help would be appreciated.
if its carb'd give the carbs a good cleaning too.

kenny
 

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ass hole extaordinaire
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so as soon as the clutch is released it dies sounds like it could be a safety switch try bypassing the safety switches and see what happens
 

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ass hole extaordinaire
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if its carb'd give the carbs a good cleaning too.

kenny
just busting horns but have you ever seen a vn750 with fuel injection?
 

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Chasin' the blacktop
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Discussion Starter #5
There is no clutch safety switch. I bought it last summer with 3000 miles on the clock. It now has 8900 miles on it and was running fine until kaput. I can rebuild the carbs but I really don't think the problem is in ths carbs. It started very suddenly and both exahaust pipes feel like both cylinders are running when it runs in neutral although as I mentioned before one of the exhaust pipes feels a bit cooler than the other.
 

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make sure your fuel tank venting system is open and clean....search for threads on POOGS.

Backfires and crappy running is sometimes the cause of a weak battery. What type of battery do you have? is it on a trickle charger?

If the safty switch...or switches are bypassed...check the connections to make sure they are good and also check your battery and frame grounds while you are at it.
 

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Chasin' the blacktop
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Discussion Starter #7 (Edited)
The battery is an AGM replaced last summer. I had heard about the vulcan's recharging system weakness so I got a good battery. The bike had been running about 50 miles before it died. How do you check the tank vent system. Is it the little metal tube on the back of the tank? I did hear a little whiseling sound from the fuel cap after running the bike for 20 minutes so I left the gas cap open before engauging the clutch. same result. the bike didn't die but only because I squeezed the clutch before it could.
 

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Chasin' the blacktop
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Discussion Starter #9
My bad. Yes there are wires plugged into the clutch lever. When the transmission is in neutral the bike runs the same whether the clutch is in or out. With the engine running @ 2500 rpm before letting the clutch out it barely bumps the bike forward if I release the clutch killing the engine. It revs great but no power.
 

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ass hole extaordinaire
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if you have a short peice of wire about 5 inches or so try jumping the safety switches to ground i will go out to my bike and get you the color and position of the wire just give me a quick sec
 

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ass hole extaordinaire
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ok just looked it is the second wire from the bottom (black wire) on the ten wire connector at the junction box strip back a bit of inosation to expose the wire and use the jumper wire to ground it to the frame
 

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Chasin' the blacktop
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Discussion Starter #12
All the spools of wire are at my shop 10 miles away. Please send me your information and I'll get back to you after I get some wire.
Spencer
 

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The battery is an AGM replaced last summer. I had heard about the vulcan's recharging system weakness so I got a good battery. The bike had been running about 50 miles before it died. How do you check the tank vent system. Is it the little metal tube on the back of the tank? I did hear a little whiseling sound from the fuel cap after running the bike for 20 minutes so I left the gas cap open before engauging the clutch. same result. the bike didn't die but only because I squeezed the clutch before it could.
At the base of the gas cap is a tube that runs down the inside of the tank and exits just in front of the seat. the tubing coming off the tank runs down under the bike. Those need to be clear along with the venting system inside the gas cap. The cap seals against the opening when the gas cap is locked.
The hissing sound could indicate the cap is not venting. If you opened the cap it should equalize the pressure inside the tank to ambient pressure. It's the vaccum created in the tank by a faulty vent that will basically stop the fuel flow.

As far as wiring goes...I strongly suggest unbolting, cleaning and reassembling the grounding wires and the battery. This is known to cause similar issues.

If the sidestand switch, clutch switch or any others were bypassed. Inspect them and clean them.....a twisted together wire, or crimped connection will oxidize and act like an intermittent connection which could aslo be the issue here.
 

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ass hole extaordinaire
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it is odd that every one talks about bypassed safety switches but every since i have had my bike i have been able to ride off with the stand down and engage the starter with the clutch in or out no matter the gear that it is in i have even switched the whole harness and all saftey switches with that of another bike the only time my bike failed to start due to safety switches was when i had a faulty connection in the clutch switch due to condensation so i am guessing that all my switches are stuck in go mode
 

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My '03 dies out if I let the clutch out with the sidestand down.
 

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Chasin' the blacktop
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Discussion Starter #18
Success

Well it's up and running now. kc2dgg, I double checked all the electrical connections like you suggested including unplugging and reconnecting the modgule but no go. New Rider 9984 got it right when he suggested checking all of the safety switches. The kick stand safety switch was the culprit. Maybe a rock got tossed up and hit it??? anyway the plunger was slightly bent and sticking. After bypassing it I went for a ride (my foam air filters were on but the covers were off) and it ran strong up to about 4000 rpm and barely pulled past 5000 rpm before topping out. I remounted the air filter covers and now the bike runs good as new. I figured that with the foam filters on the vacume would be good but I was surprised that the covers made that much difference.
Thanks for all of your help guys.
Spencer
 

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Let's Ride!!
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it is odd that every one talks about bypassed safety switches but every since i have had my bike i have been able to ride off with the stand down and engage the starter with the clutch in or out no matter the gear that it is in i have even switched the whole harness and all saftey switches with that of another bike the only time my bike failed to start due to safety switches was when i had a faulty connection in the clutch switch due to condensation so i am guessing that all my switches are stuck in go mode
Sounds like you either don't have one, or it's been bypassed, or maybe the button of the switch has been broken (this was the story with mine for a while). It's fine, it will work without one or with it bypassed. The only difference is that if you are in gear, you can hit the starter button which will lurch the bike forward if you don't have the clutch pulled in. It's really not a big deal.

To check if you have one, it's on the underside of the clutch lever's pivot bracket. Should have two wires leading into it. I'll snap a picture for you if you'd like.
 

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I just experienced identical symptoms to Spencer, lucky thing I checked this web site before wasting time and effort because I would never have thought that the kick stand switch would cause the bike to run like crap. But a dirty switch was the problem. Seems to me that the switch should not let u start the engine at all, but if it is open, it will start (very hard) it idles rough and will die under the slightest load. Anyway , I eliminated the switch with jumper and problem solved...VN 750 forum fixes another problem.....THanks to all
 
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