Stalling Question. Help appreciated. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

LinkBack Thread Tools Display Modes
post #1 of 24 (permalink) Old 10-26-2011, 10:41 PM Thread Starter
Senior Member
MaDeInSin's Avatar
Join Date: Oct 2011
Location: Waldorf, MD
Posts: 483
iTrader: (12)
Stalling Question. Help appreciated.

Ok. I am as most of you know pretty new here and I don't know a bunch about motorcycles. My 1994 Vulcan 750 runs pretty good most of the time but I have one complaint and I guess I want to see if its normal.

1st. I have to start it on full choke and give it a few minutes of warming up before it will stay running with no choke. (Not a big deal but wanted to note it)

2nd. It doesnt seem to matter how long I let it run for when this next problem occurs. It doesn't like to go right away. As I let of on the clutch and give it gas it just stalls. The thing I noticed is when I let of on the clutch the RPM gauge goes a little wacky until it either stalls or I pull the clutch back in.

When the bike finally moves I notice the gauge is acting fine. While I am driving I have no issues but as soon as I stop, cut if off and go to start again I have to deal with it all over again.

Lastly.. I was in stop in go traffic for a little while yesterday and my while in 1st gear and the clutch being held my rpms got up to 4-5k. I had to let the clutch about halfway out for the rpms to drop back down. Now I didn't notice the problem today but I was not in stop and go traffic. Wierd?

Any direction would be great.


MaDeInSin is offline  
Sponsored Links
post #2 of 24 (permalink) Old 10-27-2011, 07:13 AM
Members who have donated towards server costs
eriedoc514's Avatar
Join Date: Oct 2011
Location: Jacksonville, NC
Posts: 35
iTrader: (0)

That is kind of a weird case ya got there....

1) As far as starting the bike goes, i think it is pretty normal to have to run with some degree of choke for a few mins, to get the bike warm. You are probably going to have to use it more and more as the weather continues to drop in MD.

2) this one i think there might be a few other questions. Like when you go to start out on the bike, how does it run in the lower end of the RPM range? Is there any hesitation or excessive vibration until you get to like 3k? When my bike had a clogged low speed jet on the front jug, i was only running on the rear cylinder till about 3000 rpm and that made starting out a nightmare, the bike was very touchy till that got cleaned. What are the condition of the carbs? Have you been in them before, and how long have you had your VN? Has it been sitting for a while? What do the plugs look like?

3) The stopped in traffic high rev, also makes me wonder about a few things in the carbs. Just to get it off the table, have you tried adjusting the idle (only do this when the bike is fully warm)? Idle range for these bikes is 1100 +/- 50 rpms (per service manual). But truly it sounds like there may be some gunk stuck in one of the float needles, causing it to stay open.

-easy thing to do for now, is to put about 1/2 can of seafoam in the tank and take her for a hard ride. See how that goes. Also some of the guys here have talked about disconecting the fuel lines from the petcock and filling strait seafoam into the carbs, letting it sit overnight and then draining from the float bowls. Then taking her out. If those dont work or solve the problems, you may benefit from pulling the carbs, cleaning them well and report back what you find.

I am no mechanic, i am sure others will chime in with more detailed responses. Hopefully you get this figured out. Good luck and keep us posted. posted.

eriedoc514 is offline  
post #3 of 24 (permalink) Old 10-27-2011, 10:30 AM Thread Starter
Senior Member
MaDeInSin's Avatar
Join Date: Oct 2011
Location: Waldorf, MD
Posts: 483
iTrader: (12)
Kevin- thanks for your advice. I am currently using sea foam
So far about 1 tank full has ran through. My idle rpm is over 2k. So I should adjust that down to 1100 or so using the Idle screw? I think I am going to attempt takingt
The carbs off and cleaning them as you suggested. I am currently at work so o do not have my clymer manual handy. What tools and cleaners are needed to clean the carbs? I would like to pick them up on the way home... Thank you!!
MaDeInSin is offline  
post #4 of 24 (permalink) Old 10-27-2011, 11:03 AM
Members who have donated towards server costs
flitecontrol's Avatar
Join Date: Dec 2008
Location: Monroe, LA
Posts: 4,699
iTrader: (14)
I would give the Sea Foam some time before pulling the carbs. Or drain the gas from the carbs and fill with straight SF and leave it for a day or two.

Some folks say you'll need another brain to remove the carbs properly, cause you're gonna blow the first one out just removing them.

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
"Black Beauty"
1989 VN750 acquired December, 2008, 6,711 miles
Currently 23,298 miles

Old Blue
2001 Honda CMX250 Rebel acquired July, 2008

1987 VN750 project bike, acquired August, 2009, 33,000 miles and balancer sticking out of the case, currently awaiting attention and parts
flitecontrol is offline  
post #5 of 24 (permalink) Old 10-27-2011, 11:43 AM
Senior Member
Join Date: Aug 2011
Location: Oklahoma Panhandle
Posts: 131
iTrader: (0)
I'm going to have to agree that this sounds like problems with the pilot jets. If that's the case, running Seafoam while you're riding won't be much help unless you spend most of your time around idle. I'm going to venture a guess that the PO turned up the idle because it starts running rough when you back it down closer to spec...

The idea of filling the carbs with straight Seafoam and letting it soak is a good option. Give it a day or more to work it's magic, then drain. Alternately, you could pull the drain screws and spray a generous amount of carb cleaner up and try to flush the gunk out. I would definitely try one (or both) of these methods before subjecting yourself to the pain of pulling the carbs.

Good luck!

2005 VN750 upwards of 14K (haven't looked lately)

AGM Battery
Headers wrapped
Custom paint
hot_rod_hippie is offline  
post #6 of 24 (permalink) Old 10-27-2011, 04:46 PM
Members who have donated towards server costs
Join Date: Nov 2007
Location: Chandler, Arizona
Posts: 2,888
iTrader: (0)
The only odd part I see is the last one, where the engine RPMs went way high. That can only be caused by opening the throttle. To run faster, and engine must have more air/fuel mixture. And since this is not a Toyota, and actually has mechanical throttle cables connecting the throttle to the carb, either the throttle got moved, the cables are binding, or they are routed incorrectly, and opened the throttle when you turned the handlebars. Since it is mechanical, the cause of that problem should be easy to track down.

Even in AZ, in the summer, in the shade, my Vulcan takes full choke to start, and needs at least partial choke to run for the first couple of minutes (it is actually an enrichener circuit, not a true choke, and works in a completely different way, but I don't believe that is relevant here)

The stalling could very well be caused by a partially plugged pilot jet. That could also be the reason it needs more choke than you seem to feel is necessary. Before removing and dissassembling the carbs for a thorough cleaning, there are a couple of things you can try. First of all, if the carbs still have the EPA plugs in them, covering the pilot screws, you need to remove them, then remove the screws and springs, spray some carb cleaner back in there where the screws go, put them back in, lightly seat them, then back them out 2 1/2-3 turns. Do this even if the plugs have already been removed.

Now remove the fuel lines from the petcock, and drain the flat bowls on the carbs (make sure what kind of drain screw you have, mine has Allen screws, apparently some had straight slotted screws) You loosen the drain screws and the gas will drain out. Now close the drain screws, and using a very small funnel, fill the carbs with Seafoam through the fuel lines, let it soak for at least 24 hours, and drain it out. Put the fuel lines back on, close the drains, and restart the bike. It will take a little longer than usual, because the carbs will have to fill back up with gas. Now run a couple of 16 oz cans of Seafoam through the tank, one full can per full tank. If that doesn't help, you are probably looking at pulling the carbs to clean them.

The tach shows actual engine rpms, and readings will vary considerably. It is probably just reacting to different engine speeds if the engine is not running consistently. If there is a problem with it, it is totally unrelated to your other issues.

I am a motorcyclist, NOT a biker.

1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
VN750Rider/Jerry is offline  
post #7 of 24 (permalink) Old 10-27-2011, 04:58 PM
Crap, I WAS in 5th gear.
Join Date: Sep 2011
Location: So. Cal
Posts: 500
iTrader: (1)
Pipe cleaners and carb cleaner. Some guys can get the pilots out without removing the carbs- I tried, and you need exactly the right 90-degree screwdriver, so I gave up. Before you pull the carbs, "standard procedure" is to make sure that there are no air leaks in any tubing or boots, that you have adequate fuel flow through the petcock, your tank vent(s) are clear, your float level is correct, and that your coasting enricheners are in good shape.
Kelly2001 is offline  
post #8 of 24 (permalink) Old 10-27-2011, 06:38 PM Thread Starter
Senior Member
MaDeInSin's Avatar
Join Date: Oct 2011
Location: Waldorf, MD
Posts: 483
iTrader: (12)
Thanks Everyone for your reply's. I have been looking in the clymer manual and at my bike for over an hour now trying to figure out and understand everything you guys are talking about before I take on the job.

A few things that hopefully you wont mind clarifying. What are EPA plugs and where are they located exactly? I can follow the directions after that but I can't find anything about them in the manual.

Is the petcock the fuel shutoff valve under slightly under the gas tank?

Thank You again.

MaDeInSin is offline  
post #9 of 24 (permalink) Old 10-27-2011, 10:13 PM Thread Starter
Senior Member
MaDeInSin's Avatar
Join Date: Oct 2011
Location: Waldorf, MD
Posts: 483
iTrader: (12)
HAHAHAHAH SUCCESS!!! Or partial....

Okie dokie.. So I believe I have successfully managed to fill the flat bowls with Sea Foam. Those now need to soak for 24hours. I even attached a photo to celebrate my victory!

Secondly. I still am not sure where the EPA's are located nor the pilot screws. Maybe if someone could look at my picture and give me a little direction there. That would be great.

Also- When I took my gas tank off I noticed at the very tail of the tank is a little metal tube that was not connected to anything. Should it be? I see the other side of it as well and it looks to have been purposely disconnected. You can see this tube in picture 2

Lastly I included a photo to show how awesome my woman is.. Yes.. Yes.. I am working on my bike in our living room. !

Ok .. Seriously. Thanks all and I look forward to a little more advice and direction.



Last edited by MaDeInSin; 03-16-2012 at 11:41 PM.
MaDeInSin is offline  
post #10 of 24 (permalink) Old 10-27-2011, 10:31 PM
Linkmeister Supreme
OlHossCanada's Avatar
Join Date: Aug 2008
Location: Lethbridge, Alberta, Canada
Posts: 7,960
iTrader: (8)
First thing I will give you a link to Crobin 365`s pics in the gallery.
There are probably over a hundred carb pics there, with labels!

What Jerry calls the EPA plugs, are lead plugs over top of the fuel/air mixture screws. The Environmental Protection Association mandated them to keep owners from messing with the carbs. (Ha, we know how to get around them!!)

Yes, the petcock is the fuel shutoff valve.

The metal tube on the back end of the tank is a vent that runs up to the filler cap. Some early models don`t have one.
California models often have two tubes on the tank.

Take a look at this link on POOGS, and how to cure it by cleaning the vent tube and hose.

Hope this helps you Jay.


1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


Last edited by OlHossCanada; 10-27-2011 at 10:47 PM.
OlHossCanada is offline  
Sponsored Links


Quick Reply

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:


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