Trouble starting/loss of power - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 07-06-2014, 06:17 PM Thread Starter
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Trouble starting/loss of power

I honestly have no idea which area this is going to fall under, so I'm tossing it out here (some of it is electrical I suppose, but I'm not sure the entire thing will fall under that classification). I've got a 1991, which I bought about 3 years ago. I've never had a battery last more than one season, but for the first two years I was stupid and didn't put the battery on a tender during the winter so I figured that was the issue. Had it on a tender all winter this past season, got it out of storage and it fired up pretty quick. Rode it for a month or so with no issues at all. Within the past month or so, it's been having trouble starting. It's working to turn over but it just won't fire up at first. It usually fires up after a couple tries (I've found it starts better if I leave the choke closed, twist the throttle once or twice while starting, then open up the choke after it fires up). A week or so ago, the battery completely died while I was at work. I shoved it down the hill and pop-started it, let it run for a few minutes, then headed home. It tried to die after a minute at the first stop light; I revved the engine a bit and it was OK. Getting on to the highway, it suddenly felt completely sluggish, like the engine was running but there was no power. I couldn't get over 50 mph. Was about to pull over when suddenly it sprang to life and everything was fine. I have about 12-15 miles of interstate on the way home, and it ran that with no problem at all. Get off the interstate, hit a stop light. No issues. Go half a mile, and sluggish again; this time I can't get it over 35 mph. Just as I was pulling over, it came back again and I was able to ride the last few miles home without incident.

I've had a ton of possible issues suggested to me, from spark plugs to bad battery to bad alternator to gummed up fuel lines. The feel I get from it is that the engine is running fine, but isn't providing any power. Problem is, I know next to nothing about these things so I have no idea what those symptoms would indicate. Money is tight right now so I'd really like to avoid trying 5 different things before I find the real issue. Any help you guys can provide would be much appreciated!
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post #2 of 7 (permalink) Old 07-07-2014, 11:33 PM
Glenn C.
 
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Welcome to the forum.

And first off, these bikes dont have alternators, they have stators and regulator/rectifiers.

The regulator/rectifier, also referred to as r/r or rr, is mounted under the battery and above the exhaust belly, a bad bad spot, as it overheats and goes bad. When that happens it will also take out the stator in the engine.
Many of us have relocated the r/r to the area back by the passenger footpeg. (pic below)

If the stator goes, you have to pull the engine to replace it. there is a mod you can do so that if you have to replace the stator again later, you dont have to pull the engine. many vn750 owners do this mod. (pic below)

Now if you are having starting and idiling issues it could be the carbs. try running some seafoam thru the gastank.

I highly suggest you do seafoam and get new spark plugs. Also check your air filters too!!

Next invest in an LED Voltmeter gauge to monitor your battery power level while riding. This can help determine if your battery is being charged, and can rule out if its the R/R or Stator or not.

PICS for stuff mentioned above.

R/R relocation mod


Stator Plate Mod

Glenn C
Alexandria, MN
My VN750 Page
VN750 Stator Plates and Products

2001 Kawasaki Vulcan VN750
1986 Kawasaki Vulcan VN750 (being restored)
1986 Kawasaki 454LTD (being restored)
1985 Kawasaki 454LTD (being restored)

Last edited by gcextreme; 07-07-2014 at 11:38 PM.
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post #3 of 7 (permalink) Old 07-08-2014, 10:43 PM
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Easy way to start testing to see if your charging system is shot/dying is get a voltmeter and test the battery. With the key off the batt should put out about 12.5-13 volts ish
With the engine running right around the same. Twist the throttle and hold it and the Volts should go up to 14-14.5 ish

If the voltage does not go up while the throttle is open, your not charging, and its time to think about talking to Gcexteme about his stator plate
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post #4 of 7 (permalink) Old 07-09-2014, 12:06 AM
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The way you describe it, makes me think of how the bike behaves when you're riding it and fuel gets low and the bike gets all sluggish and you have to switch to reserve and when you do, it suddenly bolts back into action. Does it feel kinda like that at all? If so, there might be something blocking fuel flow at some point. Tank, petcock, fuel lines, carbs... that's where I'd start looking. Also might want to check the vacuum line that actuates the petcock. Could be lots of things, but this seems like a fuel problem to me from that description.

1985 VN700 unknown mileage (over 33K)

AGM Battery
Iridium spark plugs
NGK wires and caps
Relocated R/R
Marbled
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post #5 of 7 (permalink) Old 07-09-2014, 12:09 AM
Glenn C.
 
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Quote:
Originally Posted by jayceepage View Post
A week or so ago, the battery completely died while I was at work. I shoved it down the hill and pop-started it, let it run for a few minutes, then headed home. It tried to die after a minute at the first stop light; I revved the engine a bit and it was OK.
This sounds like a battery charging issue tho...


Quote:
Originally Posted by jayceepage View Post
Getting on to the highway, it suddenly felt completely sluggish, like the engine was running but there was no power. I couldn't get over 50 mph. Was about to pull over when suddenly it sprang to life and everything was fine. I have about 12-15 miles of interstate on the way home, and it ran that with no problem at all. Get off the interstate, hit a stop light. No issues. Go half a mile, and sluggish again; this time I can't get it over 35 mph. Just as I was pulling over, it came back again and I was able to ride the last few miles home without incident.
This sounds like a fuel issue like Ceal said.

Glenn C
Alexandria, MN
My VN750 Page
VN750 Stator Plates and Products

2001 Kawasaki Vulcan VN750
1986 Kawasaki Vulcan VN750 (being restored)
1986 Kawasaki 454LTD (being restored)
1985 Kawasaki 454LTD (being restored)
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post #6 of 7 (permalink) Old 07-09-2014, 12:19 AM
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I missed that part you pointed out gc. I think this would go forward much easier by taking measurements with a voltmeter or multimeter first.

1985 VN700 unknown mileage (over 33K)

AGM Battery
Iridium spark plugs
NGK wires and caps
Relocated R/R
Marbled
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post #7 of 7 (permalink) Old 07-09-2014, 02:39 PM
Glenn C.
 
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Yea test it with a multimeter and test the r/r and stator too.
If those check out then it has to be a fuel or spark issue.

Glenn C
Alexandria, MN
My VN750 Page
VN750 Stator Plates and Products

2001 Kawasaki Vulcan VN750
1986 Kawasaki Vulcan VN750 (being restored)
1986 Kawasaki 454LTD (being restored)
1985 Kawasaki 454LTD (being restored)
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