Carb / engine Question - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
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post #1 of 9 (permalink) Old 05-30-2018, 05:04 AM Thread Starter
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Carb / engine Question

Hello, everyone I have bought my bike a few months ago and it ran fine. The only issue I had was a lot of backfire while decelerate (slowing down). Two weeks ago I decided to change the oil on it and noticed the last owner never change it, the oil came out milky (horrible I know). After changing the oil I took it for a test ride and it seem a lot smoother. After that I let the bike seat for a week since I left out of town. When coming back home I was super excited because I went a whole week without riding and I saw everyone riding while I was in L.A. I try to start it up, fire right up and let it warm up on my street, I notice a bunch of fuel leaking from the right exahust pipe. Oh crap I remember the kids were playing with my throttle, crossing my finger and hopping it isn't flooded as bad. I rode the bike around the neighborhood and it seem to choke anything under 3k rpm but as soon as you pass 3k all the power creep up. I ask around all my buddy who ride told me that it's more then likely my carbs are flooded. Hopping it wouldn't be true, I changed out the spark plugs, new battery (since the old one drain and wouldn't recharge). I try to start it up again then I notice the right exhaust wasn't blowing out as hard (normal) like the left side. They weren't anymore leak so I figure I'll leave it for a few day and I'll try to start it again. After a few day I started it up and notice it was still doing the same thing. So, I suck it up and took apart the carbs. Open everything up and clean it with carb cleaner, everything seem to look good even the float blow look good, no rust of any sort. After struggling with the Airbox ear I decided to take them off so my life would be easier without them. Carbs went in perfect, got everything hook up and hoping I didn't screw anything up. I hook up the fuel tank and total forgot what tube went to what, so I was like screw it I'll wing it and hope it work. Started up the bike and it started up with no issue and I notice they where a little drip of gas from the exhaust pipe(right side) I turn it off and try to started again and it would turn on for a few seconds and then die. After while I then I remember crap! I should of done a oil change on it. Drain out the oil and they where a smell of gas coming from the oil.

Questions:

1)Would having a mixture of oil/gas prevent my bike from starting ?

2) Would the bike start up without an air filter?

3) Tube connection left side(top carb) to left nipples on left of peak coak Rear/ back carb to right peak coak nipples. Middle tube straight up to the straight nipple on peak coak. Tee Connected from the right side and middle with a extra tube hanging for breather.

Still need to put in oil and hoping someone can answer if my tubing connection is correct before I try to start it back up. Also, I would take out the new spark plugs and clean them to see if it would start up after the oil change.

Thanks in advance! #MileHighVulcan
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post #2 of 9 (permalink) Old 05-30-2018, 11:22 AM
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Gas in the oil shouldn't make it not start. It'll just wear out your engine super-quick.

The bike COULD start without an air filter, but would probably run lean because it would be getting unrestricted air flow. Might cause you problems starting.

Not sure about the hose routing. Fuel lines go on right and left of petcock. Vac tube attaches to the bottom. Unfamiliar with any tees in the lines.

It definitely sounds like at least one of your carbs is leaking fuel into the cylinder. The float itself might be getting stuck, or the needle valve might be worn out.
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post #3 of 9 (permalink) Old 06-01-2018, 08:47 AM
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Just sounds like you need to clean out your idle circuit on your carbs. Dry a healthy dose of sea foam first. But my bet is you need to clean em. Not a huge deal. Let me find a good carb video I found.

This will explain why it works at higher RPM and not lower.


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post #4 of 9 (permalink) Old 06-01-2018, 04:24 PM
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If one side of your exhaust doesn't seem to get hot, then it could also be a stuck float needle. I pulled a carb one time to clean it and it was so gummed up it didn't move at all.

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post #5 of 9 (permalink) Old 06-01-2018, 05:53 PM
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I will add, the exhaust pipe on the left (rear) side is singlewall, where as the right side is double wall until the goats belly. right side will take longer to heat up than left

all of course is assuming stock exhaust

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post #6 of 9 (permalink) Old 06-01-2018, 11:01 PM Thread Starter
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Quote:
Originally Posted by Goofyfoot2001 View Post
Just sounds like you need to clean out your idle circuit on your carbs. Dry a healthy dose of sea foam first. But my bet is you need to clean em. Not a huge deal. Let me find a good carb video I found.

This will explain why it works at higher RPM and not lower.


Thank you that help a lot.
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post #7 of 9 (permalink) Old 06-01-2018, 11:05 PM Thread Starter
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Thanks guys I'll look into it again, still crossing my finger that when I put in fresh oil again it would run. If I have to takeout the carbs again it would be super easy to take out, since I have the air vent ear shave off and installing k&n filter pod.
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post #8 of 9 (permalink) Old 06-03-2018, 10:37 AM
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Quote:
Originally Posted by Goofyfoot2001 View Post
Just sounds like you need to clean out your idle circuit on your carbs. Dry a healthy dose of sea foam first. But my bet is you need to clean em. Not a huge deal. Let me find a good carb video I found.

This will explain why it works at higher RPM and not lower.

https://www.youtube.com/watch?v=IBFq9nHVmks
The same symptoms happen with a stuck float.gas floods the spark at low rpms and motor iicks in about 3-4000 rpms

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post #9 of 9 (permalink) Old 06-03-2018, 02:31 PM Thread Starter
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**update** oil came in early and and went and got a k&n filter from advance auto and got her running. Only problem I have now is the bike doesn't want to run without choke. Guessing maybe due to taking off the air box they're not enough pressure holding onto the choke cable.

Last edited by MileHighVulcan; 06-03-2018 at 03:01 PM.
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