Bogging down@ 50 mph, here is the likely culprit! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 12 (permalink) Old 06-29-2014, 09:18 PM Thread Starter
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Bogging [email protected] 50 mph, here is the likely culprit!

Since this has been a problem with me and many members here I thought I'd post some decent pics since I have my bike apart since all these parts are so hard to see with the motor in!

Here is the T connection between the carbs that comes off the vent from each carb



This is the hose coming off the t which should go to the right ear, the end closest to my fingers is what you want to cut at a 45 degree angle





And lastly here is a pic of the right ears backside, the hose should be pushed into the round hole below the square hole, I wrapped a few layers of tape around mine to make it snug, the 45 degree cut just keeps it from bottoming out so it can get air, but not too much.



hope this helps in someone in the future! If the mods dont sticky this I will save it to my sig line for quick reference. might keep someone from tearing down their carbs when they dont need to!

1986 vn 750 aka "Huck Farley"
42,000 miles
Rick's stator and rr
Tuxedo stator cover mod
pickup coil mod
dampers replaced
agm m/f battery
Harley sportster exhaust, degoated
Hid conversion
splines lubed
custom "vn750.com" grill cover
NGK Iridium spark plugs


acct to mcct mod https://www.vn750.com/forum/showthread.php?t=17917

rekeying locks, https://www.vn750.com/forum/showthread.php?t=7309

stator replacement walkthrough, https://www.vn750.com/forum/showthread.php?t=11369
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post #2 of 12 (permalink) Old 06-29-2014, 11:05 PM Thread Starter
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Thanks for the sticky, saves room in my sig line for mods!

And to further explain the symptoms, the bike might run fine right up to 50mph and then star to sputter and hesitate, rough through it and get up to 55-60 and it straightens out! this is what mine and several others did. mine was missing the t and hose to the ear plus one off the carb, replaced all that and never had a problem since, why at 50mph only is beyond me, i would think it would be 50 and up but wasnt the case.hope this helps!!!!

1986 vn 750 aka "Huck Farley"
42,000 miles
Rick's stator and rr
Tuxedo stator cover mod
pickup coil mod
dampers replaced
agm m/f battery
Harley sportster exhaust, degoated
Hid conversion
splines lubed
custom "vn750.com" grill cover
NGK Iridium spark plugs


acct to mcct mod https://www.vn750.com/forum/showthread.php?t=17917

rekeying locks, https://www.vn750.com/forum/showthread.php?t=7309

stator replacement walkthrough, https://www.vn750.com/forum/showthread.php?t=11369
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post #3 of 12 (permalink) Old 04-20-2015, 01:36 PM
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Thanks for posting this I could not figure out where this guy went.

1985 Vulcan VN700A1
1976 Chevy Nova (project car)
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post #4 of 12 (permalink) Old 03-19-2016, 05:52 PM
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I am having the same issue with mine bogging down at about 4000-5000 RPM. I noticed that on mine, I have a total of 3 hoses for the carb, 2 going from the tank to supply fuel to the carbs and one vacuum line going form the left carb to the 3 position valve coming out of the tank. I don't have any T linking the 2 carbs. I noticed that on the right carb there is a plug as shown on the picture. I f put a T as shown in Sticky video, where should I connect these?
Thanks,
Charles
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post #5 of 12 (permalink) Old 03-19-2016, 07:19 PM
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there is a fitting on each carb (in the 'middle' of the sandwich) that vents each bowl.

you need a vent on them fittings. you can do individual lines for each carb, but most take short hoses from the fittings to a "T" fitting, then a single line from there to a dead air spot. Under tank is good (on top of a frame rail, or on the extra fitting on plastic cover for the fuel gauge), or if you still have ears, the right ear.

the pics you posted are of the outside facing parts of the carb. the lines there and the plug are correct if your ear shaved.

2005 VN750

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post #6 of 12 (permalink) Old 03-19-2016, 07:37 PM
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I did find the T as you mentioned after a second look. The T do connect both carbs and then a hose coming out of the T goes under the tank . Since I am experiencing the issue that Wib714 is talking about, maybe I need to take that hose to the right ear to restrict the air a little bit.
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post #7 of 12 (permalink) Old 03-19-2016, 09:43 PM
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where under the tank does it go? if it goes to the nipple where the fuel sender is, or is secured to the top of a frame rail in same area, you may have a different problem. those 2 locations are where most people put the hose and have no problems.

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post #8 of 12 (permalink) Old 03-19-2016, 10:56 PM
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Yes I always go for the nipple

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post #9 of 12 (permalink) Old 03-19-2016, 11:27 PM
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The tube was left open under the tank. I got 6 more inches of tubing and connected to the right ear above the square hole of the air cleaner and making sure that the tubing was cut at 45 degree as mentioned on the post above. Everything is now working fine at 4000-5000 rpm.
Thank you all for your help!!
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post #10 of 12 (permalink) Old 09-06-2018, 11:30 PM Thread Starter
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Bump, and what happened to all the stickies?

1986 vn 750 aka "Huck Farley"
42,000 miles
Rick's stator and rr
Tuxedo stator cover mod
pickup coil mod
dampers replaced
agm m/f battery
Harley sportster exhaust, degoated
Hid conversion
splines lubed
custom "vn750.com" grill cover
NGK Iridium spark plugs


acct to mcct mod https://www.vn750.com/forum/showthread.php?t=17917

rekeying locks, https://www.vn750.com/forum/showthread.php?t=7309

stator replacement walkthrough, https://www.vn750.com/forum/showthread.php?t=11369
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