Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums - Reply to Topic
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

Thread: boggs down off idle Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

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


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

Email Address:


  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
12-15-2017 06:04 AM
WestOzzBazz Gid'day all,from downunder.Having same problems after mini rebuild.Had ignition problems with green death on coil spikes/plug leads.Rectified them,new slow jets#38.Now runs smooth on start/idle,up to about 4000rpm.Will run up to 6,if throttle opened slowly,but if blipped ,sounds like starving for fuel.Am checking all vacuum lines,boots.Havnt adjusted floats,levels ok.Will remove carbs (again) to check diaphrams??
09-30-2017 07:07 PM
Spockster 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.
09-30-2017 03:52 PM
richny 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.
09-30-2017 01:43 PM
Spockster 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?
09-30-2017 01:02 PM
richny 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.
09-28-2017 12:30 PM
Heckler94 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.
09-28-2017 01:06 AM
Spockster 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.
09-27-2017 06:58 PM
richny 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...
09-20-2017 11:47 AM
cglennon Did you balance the carbs after the rebuild?
09-20-2017 11:00 AM
ubertalldude did you re-jet at all, or just deep clean them?
This thread has more than 10 replies. Click here to review the whole thread.

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

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