boggs down off idle - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 09-20-2017, 09:15 AM Thread Starter
Junior Member
 
Join Date: Feb 2017
Posts: 8
iTrader: (0)
 
boggs down off idle

Hey all, just rebuilt the carbs. Bike starts right up and idles however, when I goose the throttle it seems like(and does at times) want to die out. If I open and close it quickly a couple times she'll rev high or if I ease it on, but from an idle when I snap it open seems like it just wants to bog down and die. Haven't ridden it yet as its not tagged. Also seems like the rear cylinder isn't firing completely, which is why I rebuilt the carbs in the first place. Has v+h pipes and you can def hear the right exhaust louder than the left until the rpm's get up some.
99 vn750 with 20,000 miles. just bought it a few months back
richny is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 09-20-2017, 11:00 AM
Senior Member
 
ubertalldude's Avatar
 
Join Date: Jun 2016
Location: NE Florida
Posts: 662
iTrader: (0)
 
did you re-jet at all, or just deep clean them?

Earshave+Rejet (38/135) – NGK Iridiums – MCCT Conversion – Slipstreamer S03 Windshield – Custom Extended Backrest – Custom Highway Bars – MOSFET R/R – LED Underglow – Volt+USB In-Dash – Two-Wire & Blue-Wire Mod – Satin Black Engine Paint – Dampers Parts - Jets: Main=99101-393(#132 stock)/Pilot=n424-22 Pilot(#38 stock)
ubertalldude is offline  
post #3 of 11 (permalink) Old 09-20-2017, 11:47 AM
Senior Member
 
cglennon's Avatar
 
Join Date: May 2008
Location: Portland, OR
Posts: 731
iTrader: (0)
 
Send a message via Skype™ to cglennon
Did you balance the carbs after the rebuild?


Chris Glennon - Portland, OR
cglennon is offline  
 
post #4 of 11 (permalink) Old 09-27-2017, 06:58 PM Thread Starter
Junior Member
 
Join Date: Feb 2017
Posts: 8
iTrader: (0)
 
Hey guys, thanks for the replys! I've been really busy at work and didn't have any free time to get back. Yep, installed all new jets and no, didn't balance the carbs. In the meantime, I drilled out the air/fuel mixture plugs and adjusted the screws. Much better now and seems fine. Took it for a test ride and won't go over 35-40 mph and 4000 rpm, though it is smooth and even. Thinking this is due to replacing the petcock with an ebay non vac style. Had to tee the carb lines together and I'm thinking it's not flowing enough gas. grr...
richny is offline  
post #5 of 11 (permalink) Old 09-28-2017, 01:06 AM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,483
iTrader: (5)
   
It should run with a tee on the lines, as long as the lines aren't running uphill, like with extra long hoses.

Earshaved or not? Where are the carb vents? Wind on the vent hose can make it run out of fuel.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
Spockster is offline  
post #6 of 11 (permalink) Old 09-28-2017, 12:30 PM
Junior Member
 
Heckler94's Avatar
 
Join Date: Sep 2017
Posts: 28
iTrader: (0)
 
Also sounds like a possible vacuum leak. Had this problem with mine... it was the front boot on the carburetor. I would check by spraying carb cleaner on your boots and if it idles up, its a vacuum leak.
Heckler94 is offline  
post #7 of 11 (permalink) Old 09-30-2017, 01:02 PM Thread Starter
Junior Member
 
Join Date: Feb 2017
Posts: 8
iTrader: (0)
 
No ear shave. Carb vent line is running under seat and down, not exposed to any wind. Same place it was before I removed the carbs. Replaced tee with a larger one, still the same. Starts right up, can rev it up sitting there, but when take off down the street it just tops out at 40 mph and about 4000 rpm. Engine runs completely smooth, no sign of bogging like out of gas. Thinking maybe float adjustment? But both being out the same seems unlikely. I could see one which may have one cylinder not running right. I'll double check the boots and the vac port to be sure it's capped off completely. sigh...funny thing is, I have a vtx 1800 and a dyna superglide and I like this better than both.
richny is offline  
post #8 of 11 (permalink) Old 09-30-2017, 01:43 PM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,483
iTrader: (5)
   
I won't say for sure it's the problem, but people have had trouble with the vent line run under the seat.

It's always the frame under the gas tank (pointing back), the blank nipple on the gas tank sender cover, or the vent hose spot in one of the ears, that works for sure. I know you said the vent was there before, just saying...

I agree on both floats being too low, big odds there. Though float level is pretty easy to check with carbs on the bike. Just a piece of clear tubing and an allen wrench?

Gas tank vent partially clogged, holding back fuel flow? Try it with the cap unlocked?

Any difference if the petcock is on reserve?

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
Spockster is offline  
post #9 of 11 (permalink) Old 09-30-2017, 03:52 PM Thread Starter
Junior Member
 
Join Date: Feb 2017
Posts: 8
iTrader: (0)
 
well the one vent line from the carb to the vac tee was off. Put that on and still the same. Tried reserve and unlocked the gas cap too. What I just noticed is the exhaust on the rear cylinder (left side) is cool, the exhaust from the front cylinder is hot. that can't be good.
richny is offline  
post #10 of 11 (permalink) Old 09-30-2017, 07:07 PM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,483
iTrader: (5)
   
You can check the plug on that cylinder, see if it's really dry and has spark. If it's dry, the carb has a stuck float or dirty jets.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
Spockster is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome