Won't start after rebuild... - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 32 (permalink) Old 05-29-2014, 02:21 AM Thread Starter
Ndr
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Won't start after rebuild...

Ok, so I'm almost at wits end with this thing.

I recently finished rebuilding the engine. I'm fairly certain that I've got the timing dead spot on. All the Timing marks were spot on when I bolted the valve covers on, and I could turn the engine freely at the crank.

I've got pretty good compression: 125 front, 115 rear per my cheap POS Harbor Freight tester.

I'm getting fuel on the plugs, can see that they're wet when pulling to check for spark as well as smell the gas on them.

I've got good spark, and I even got flames shooting out of the open spark plug hole when testing the spark.

Pulled the pod filters off the carbs to shoot some starting fluid in with no results. Also tried shooting the fluid straight into the cylinder.

Held my hand over each air inlet with the pod filters off and got good suction on each carb.

With the plugs out, the engine will spin freely no hesitation. Put the plugs in, and it will spin for several turns, then hesitate or seem to skip a beat before continuing to spin freely again.

Getting white wisps of smoke coming from the left/rear exhaust. nothing from the right/front.

Thinking it might be weak spark, I disconnected the red wires from each of the coils and ran a jumper wire straight to the battery. (no relay, just test leads with alligator clips straight to the battery)


Last thing I can think to check are that the pickup coils got switched? Can anyone confirm which position each should be in?

......I'd rather wake up in the middle of nowhere then in any city on earth.

*2014 VN900 Custom (16,200 miles and counting)
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post #2 of 32 (permalink) Old 05-29-2014, 04:33 AM
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Quote:
Last thing I can think to check are that the pickup coils got switched? Can anyone confirm which position each should be in?
...that is where I would be looking also......
I dunno your answer ....my thought is upper pulsar (pick-Up coil) would be #1 (front) Cylinder.....
....need an experienced mech here....

:smile_th

'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!
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post #3 of 32 (permalink) Old 05-29-2014, 08:30 AM
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What does the spark look like? Yellow/orange without much snap, or blue with a good snap?

To check p/u coil position: Remove one of the shallow plugs, remove the opposite wire on the same cyl, so it doesn't fire on you. Ground the plug away from the hole, Crank it over with the comp. gauge or your finger in the open plug hole. You should see spark at the same time compression hits.

Sorta sounds like too much fuel, with vapor coming out of the muffler.

Is it turning over fast enough?

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__________________________________________________ ____________
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post #4 of 32 (permalink) Old 05-29-2014, 05:18 PM
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does it ever backfire thru the carbs if so you may have your cams on the wrong heads

if you look at the gear side of the cams one set has a groove around the face of it thats the set for the rear head if they are on the wrong head you can have exactly what you described and if you turn it over with the throttle wide open it should backfire thru the carbs

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Sucks getting old but it beats not getting old.

i got my helmet but it sure makes licking the windows a chore

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post #5 of 32 (permalink) Old 05-29-2014, 05:22 PM
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rear cylinder pickup coil is on the top with black/red wire and black/white wire
front cylinder pickup coil is on bottom with black wire and black/yellow wire

Quote:
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Sucks getting old but it beats not getting old.

i got my helmet but it sure makes licking the windows a chore

cell phone number for anyone who needs it 214-516-1738

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post #6 of 32 (permalink) Old 05-29-2014, 08:23 PM Thread Starter
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Well, pickup coils were switched. Charging up the battery now since I forgot to plug it back in after my last attempts to start the bike.

Guess I'll see what it does after work in the morning.

......I'd rather wake up in the middle of nowhere then in any city on earth.

*2014 VN900 Custom (16,200 miles and counting)
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post #7 of 32 (permalink) Old 05-30-2014, 10:00 PM Thread Starter
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So... No luck getting the bike to start with a fully charged battery.
Pickup coils put in their proper position (red striped wire at the top) and gapped to .020"

pulled the front valve cover off with the engine still in the frame and I've got the proper cams up there (the ones without the groove in them)
Timing marks line up perfectly.

Not getting any backfiring or popping. I did get a single backfire out of the exhaust ONE TIME when i sprayed a few shots of starter fluid into the carbs intake holding them at WOT.

I even drained the tank and dumped in a couple gallons of fresh gas just in case that was part of the issue.

I'm at a loss here, I'm at the point here that If I have to pull the engine again to check the timing again, that the engine is not going back together and is getting parted out...

I WAS trying to be nice and fixing it up for my brother who wants to start riding, but I'm pretty much beyond the point of caring any more.

......I'd rather wake up in the middle of nowhere then in any city on earth.

*2014 VN900 Custom (16,200 miles and counting)
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post #8 of 32 (permalink) Old 05-31-2014, 01:40 PM
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before you give up try my safety switch bypass

and try to jump power straight to the coils again

Quote:
Originally Posted by denny6006 View Post
Sucks getting old but it beats not getting old.

i got my helmet but it sure makes licking the windows a chore

cell phone number for anyone who needs it 214-516-1738

photobucket link
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Last edited by new rider 9984; 05-31-2014 at 02:48 PM.
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post #9 of 32 (permalink) Old 05-31-2014, 01:47 PM
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https://www.vn750.com/forum/showthread.php?t=46010

Quote:
Originally Posted by denny6006 View Post
Sucks getting old but it beats not getting old.

i got my helmet but it sure makes licking the windows a chore

cell phone number for anyone who needs it 214-516-1738

photobucket link
http://s1066.photobucket.com/user/newrider9984/library/
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post #10 of 32 (permalink) Old 05-31-2014, 02:09 PM
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From Post #1
Quote:
With the plugs out, the engine will spin freely no hesitation. Put the plugs in, and it will spin for several turns, then hesitate or seem to skip a beat before continuing to spin freely again.
If timing is right, Good Spark, Fresh Gas............ WTF ?

Weak battery ? Try putting jumper cables on the battery....

Are the Plugs/Plugs Wires new ?

Could it be the starter not turning fast enough for a successful start ?


'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; 05-31-2014 at 02:12 PM.
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