No start after rebuild - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 9 (permalink) Old 05-19-2011, 08:13 PM Thread Starter
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No start after rebuild

So I'm sure many of you have read the troubles I've been having with my bike. Today was the 3rd time I rebuilt the carbs. I had an air leak the first time and the second time it ran great until the float valve got stuck (forgot to clean the valve itself ) ... I rebuilt it again today, careful to be meticulous about everything. My cylinders were completely flooded with gasoline so I had to drain the oil (and gas) and refill the oil. I'm relatively sure gas is getting to the carbs and I cleaned off the spark plugs, so I'm assuming they're good. I think the battery is fully charged as it seems to turn over pretty strong. But ... nothing. The gas isn't igniting. Could anyone send me in the right direction? I'm so ****ing close ... I can smell it.

Please, anyone, comments or suggestions?
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post #2 of 9 (permalink) Old 05-19-2011, 10:41 PM
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Your petcock should stop fuel flow with the engine off (no vacuum) so I'm assuming all the excitement happened as you were trying to start the bike.... carbs flooded, flodded the cylinders etc.

Pull your bowl vent line off the right ear and reroute it so it's open to the air and low as possible to the floor.

Pull the left vacuum line off the carb, set your petcock to reserve and draw a vacuum with your mouth on the line you removed. You should hear a click when the petcock opens and you should hear fuel rushing to the carbs. It SHOULD fill both bowls and stop. Check the bowl vent for dripping fuel. If so, the bowls are flooded because the floats are stuck or adjusted improperly. You can also check the fuel level with a clear hose on the bowl drain (See the Clymer manual)

If you end up pulling the carbs, you should be able to check for flooding with the carbs off. I just did and it worked pretty well

https://www.vn750.com/forum/showthread.php?t=18378
see the link

1992 VN750 dark blue / black - stock
Cobra exhaust
Oversized front tire to correct speedo & improve handling
New stator and Vreg 4/11
Sealed battery
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post #3 of 9 (permalink) Old 05-19-2011, 11:00 PM
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Good advice from Spiral. Also check for spark. Kill switch on run, pull boot off of one plug. Stick a long shaft phillips head screwdriver up into the boot making contact with the metal clasp. Have the shaft touching the engine and try to start the bike. You should see the spark jumping to the engine. If you have spark you have a fuel problem, if no spark you have an ignition problem.

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2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
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decals removed
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Last edited by JM2001; 05-19-2011 at 11:25 PM.
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post #4 of 9 (permalink) Old 05-20-2011, 08:50 AM
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I would like to retract one bit of that. I do think you should pull the bowl vent line off the right ear, but don't bother rerouting it.... That baby would have to be completely full and overflowing with fuel to run out the bowl vent line. - So don't bother.

1992 VN750 dark blue / black - stock
Cobra exhaust
Oversized front tire to correct speedo & improve handling
New stator and Vreg 4/11
Sealed battery
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post #5 of 9 (permalink) Old 05-20-2011, 11:04 AM Thread Starter
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Thanks Spiral ... I'm not trying to come off as condescending, or anything, but I'm almost certain that I rebuilt the carbs correctly. I know them inside and out by now and those carbs are put together correctly. My main concern is that the cylinders were completely flooded with gasoline, right up until the point where it was spilling out of the intake manifolds. I suspect this is the root of my problem. I drained all of the gasoline when I changed the oil, however, there's still probably a little bit left. I suspect the issue is spark and ignition, not fuel flow. The spark plugs were shot (and iridium) ... when I cleaned them off, maybe I fouled them? I have new ones coming in this afternoon. Any more advice on spark? I trickle charged the battery last night just in case I had a weak output.
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post #6 of 9 (permalink) Old 05-20-2011, 11:18 AM
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check you nutral switch, kick stand switch, clutch switch, ignition, and check for spark at the plugs.
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post #7 of 9 (permalink) Old 05-20-2011, 02:37 PM Thread Starter
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Turned out my plugs were fouled (can't clean iridium) and my battery was weak. After I swapped the plugs for new ones and charged the battery, she started right up. Still waiting on some parts but it sounds beautiful. I'll keep everyone updated.
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post #8 of 9 (permalink) Old 05-20-2011, 04:53 PM
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I just hate when that happens......I had the same thing happen to me after my friend and I rebuilt the carbs since I rejeted for earshave and V&H Cruzers. My Floats got cracked and filled with gas.....so yes.... my carb mouths were puking gas all down the sides of the engine. I pulled the NGK iridium plugs out ...let the insides of the cylinders breathe for about a week (since it was still winter) to let the gas in there evaporate. Cleaned the plugs at work with a bead blaster and high pressure air. Bought new replacement Floats and Needles.....Then put it all back together and changed the Gasoline loaded oil...(which only had 15 miles on it!) She fired up like she was straight from the showroom floor and has never ran better.

Last edited by BRET H; 05-22-2011 at 04:30 PM.
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post #9 of 9 (permalink) Old 05-29-2011, 11:35 AM Thread Starter
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Yep - Just an update. The bike is finally running as it should. I took a trip down to the beach yesterday and couldn't be happier with the work I did. Thanks everyone for their advice.
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