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post #1 of 16 (permalink) Old 05-24-2014, 11:13 AM Thread Starter
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More problems..

This seems to be getting progressively worse, to the point where I can't really go anywhere with the bike without expecting problems. I bought a battery tender a week ago thinking I had a weak battery/stator/something, hoping that would be enough to stave off issues until the fall when I can pull the engine but no dice. I went to home depot yesterday to grab a few small things (about 4 miles, 60F temps). Walked around the store for a good 20-30 minutes and came out to a bike that nearly would not start. I tried full choke, no choke, inbetween.. all I got was a backfire that sounded like someone fired a gun next to my head. She finally started with choke in the middle, giving a little gas as soon as it caught. Great! Still had to go to walmart, which was 1/2 a mile away. Get there, walk around for 10 minutes.. come out to a bike that refuses to start entirely.

Finally had to push start it (first time doing that, surprisingly not that hard after I googled it) and rode home without any issues.

I checked the electrical system last weekend, but I'm beginning to think I missed something. I'm about to go check the battery voltage to see if that's the problem again, but I'm just not sure at this point.

Another thing to note, not sure if it's related, I notice when accelerating, if I let the throttle go and pull in the clutch, the engine RPMs don't rev down very fast.. more of a slow drop to idle RPM. Obviously when accelerating and shifting, it doesn't have time to get down in RPM before I've shifted, so it just sounds a little.. off? I did check the throttle cable, when I let it go it snaps the throttle shut.
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post #2 of 16 (permalink) Old 05-24-2014, 11:52 AM
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You can have something grounding draining the battery, but I suspect stator is not outputting voltage when it gets hot.

Do the full electrical workup (DC output @ idle and 5k rpm, stator output and grounding check (both hot and cold)).

It could also be the RR getting hot, i'm not sure if you've swapped it before or moved it from the stock location. The stock location gets too hot and charging suffers.

Sadly when you got it to start the first time you probably should have gone strait home. Any time she backfires a lot and can't crank so well it's usually do to low charge. It backfires since it can't ignite fully/weak spark. Glad you got it bump started; I've been there. It was a bad battery the one time I had to do it after my charging system upgrade, so a new battery sorted it out.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350

Last edited by thtanner; 05-24-2014 at 11:54 AM.
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post #3 of 16 (permalink) Old 05-24-2014, 12:06 PM
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Yes, sounds like a weak battery to me.

Is it a wet cell or an AGM? Even an AGM can go bad, but you can't test a battery just by connecting it to a volt meter after a charge and seeing if it has 12+ volts.
You need to take it to an autozone or something and have it load tested.

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post #4 of 16 (permalink) Old 05-24-2014, 12:24 PM
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Battery voltage is important, get back to us with test results.

One thing worth noting: On warm starts, if I crack my throttle at all, I get no start and nice loud backfire.

If leave the throttle closed, she starts in half a turn every time, like turning on an electric motor. If your battery/charging checks out, try that.

I do have all the electrical mods shown in my signature, but it did the same thing (backfire/no start) when the battery, stator, and r/r were dead.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
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post #5 of 16 (permalink) Old 05-24-2014, 02:16 PM
..have a vulcan good day!
 
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Note also: The Pick-Up Coil/Pulsar Mod most often or always assists in Warm/Hot start issues.


'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!

Last edited by WilliamTech; 05-25-2014 at 07:06 PM.
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post #6 of 16 (permalink) Old 05-24-2014, 03:11 PM
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Agree, when she's hot just hit the starter. No gas. She'll start slow but the pick up speed. Go for a gel battery and good plugs.

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post #7 of 16 (permalink) Old 05-24-2014, 03:15 PM
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Quote:
Originally Posted by WilliamTech View Post
Note also: The Pick-Up Coil Mod often assists in Warm/Hot starts.

A fresh battery and this simple modification may solve your problems completely. A worn starter will cause the same symptoms as a weak battery and if these bikes draw more amperage than they should for cranking, the ignition is weakened immensely.

Do a voltage drop test on the battery as well when you try to start it with a known good battery. A hot starter has more resistance due to the heat . Bushings and brushes may be worn in the starter and it is not operating as efficiently as it should. If it started very easily when bump staring it, you can be sure there is a weak link in the power circuit to the starter. Could be the Battery, battery cables , starter wiring or the starter itself. Bad connections on any of the starter/ battery cables can be a problem as well.




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Current ride 05 1500 Classic FI
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post #8 of 16 (permalink) Old 05-24-2014, 10:53 PM Thread Starter
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Ok, so did some more looking into it. I'm fairly certain the battery is not the issue here, I checked the voltage again at various points. From a cold start this morning (been off all night), the battery ready 13.09v terminal to terminal, 13.09v terminal the engine ground.

I applied full choke, pushed the starter for less than a second and she started right up with no issues. After warm up, idle battery voltage was 13.5v. I revved up to 5k RPM, battery voltage was still 13.5v, but slowly climbed up to 13.65-13.75v. All of the readings here are battery to engine ground / frame.

Finally, I turned the engine off. Battery voltage dropped to 13.31v. I let it sit for about 60 seconds and tried to start her up. This time, I had no choke applied (the bike was warmed up and running for at least 10 minutes), and I did not give it any throttle. The starter just turns over, and over, and over... finally caught after about 4-5 seconds and started up. Battery voltage during the starter cranks was 10.85-11.0v.

After all this, I took her around the block a few times to warm things up even more. I pulled back into the garage and left her running. Battery voltage was 13.55v at idle. I turned the engine off and let her sit for about a minute again. Same as before, no choke applied, no throttle, just pushed the starter. This time around, she never started up. Just turned over and over, backfired quite loudly and never caught. I finally gave up after about 30 seconds, didn't want to drain the battery.

I let her cool down for a good hour and half and tried starting again.. full choke applied, no throttle, starts on the first crank.

Clearly something doesn't like being warm. My R/R is in the stock location, considering moving that tomorrow. I also took the battery in to two different places (O'Reilly's, and then to Advanced Autoparts, because the O'Reilly's guy looked like it was his first day); the testing equipment at both shops reported the battery to be in good to excellent condition. It's a "MagnaPower" 220 CCA sealed AGM battery, if that matters.

Plugs are brand new, though I used the existing wires. Otherwise I have not touched anything with the electrical system.
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post #9 of 16 (permalink) Old 05-25-2014, 12:21 AM
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Quote:
Originally Posted by kagaku View Post
Ok, so did some more looking into it. I'm fairly certain the battery is not the issue here, I checked the voltage again at various points. From a cold start this morning (been off all night), the battery ready 13.09v terminal to terminal, 13.09v terminal the engine ground.

I applied full choke, pushed the starter for less than a second and she started right up with no issues. After warm up, idle battery voltage was 13.5v. I revved up to 5k RPM, battery voltage was still 13.5v, but slowly climbed up to 13.65-13.75v. All of the readings here are battery to engine ground / frame.

Finally, I turned the engine off. Battery voltage dropped to 13.31v. I let it sit for about 60 seconds and tried to start her up. This time, I had no choke applied (the bike was warmed up and running for at least 10 minutes), and I did not give it any throttle. The starter just turns over, and over, and over... finally caught after about 4-5 seconds and started up. Battery voltage during the starter cranks was 10.85-11.0v.

After all this, I took her around the block a few times to warm things up even more. I pulled back into the garage and left her running. Battery voltage was 13.55v at idle. I turned the engine off and let her sit for about a minute again. Same as before, no choke applied, no throttle, just pushed the starter. This time around, she never started up. Just turned over and over, backfired quite loudly and never caught. I finally gave up after about 30 seconds, didn't want to drain the battery.

I let her cool down for a good hour and half and tried starting again.. full choke applied, no throttle, starts on the first crank.

Clearly something doesn't like being warm. My R/R is in the stock location, considering moving that tomorrow. I also took the battery in to two different places (O'Reilly's, and then to Advanced Autoparts, because the O'Reilly's guy looked like it was his first day); the testing equipment at both shops reported the battery to be in good to excellent condition. It's a "MagnaPower" 220 CCA sealed AGM battery, if that matters.

Plugs are brand new, though I used the existing wires. Otherwise I have not touched anything with the electrical system.
I am going to post a couple of links here for you to read. Start at the beginning of each and read through them. It will give you a easy way to check the charging system in this one.https://www.vn750.com/forum/showthread.php?t=24093

I found this easy modification to help mine with hot staring problems immensely
https://www.vn750.com/forum/showthread.php?t=18550

Also you didn't answer the question I asked about the rolling bump start, Did it fire up almost immediately? If it did, you have low voltage to the ignition and the starter cranking is robbing the ignition of precious voltage . You can also check this modification Fergy wrote up that applies full Battery voltage to the ignition
https://www.vn750.com/forum/showthread.php?t=17276

This shouldd save you some searching on here and provide you some more food for thought on your problem. You can probably solve this with one of these links or it could take all three. Good luck !!




If you see it on my bike I did it
VROC#30324
92 vn750(sold)
Current ride 05 1500 Classic FI
lovin' the new scoot



Quote:
"When all is said and done,usually more is said than done" UNK
Click on one x and drag to the other to read between them.

Psalm 40:1...
XI waited patiently for the Lord; and he turned unto me, and heard my cry. X
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post #10 of 16 (permalink) Old 05-25-2014, 12:34 AM
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Quote:
Originally Posted by denny6006 View Post
you have low voltage to the ignition and the starter cranking is robbing the ignition of precious voltage .
Yeah, pulling the battery all the way down to 11v.

I knew if I just waited.
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