Sputtering and dieing under 4000 rpm - 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 14 (permalink) Old 11-01-2009, 03:23 PM Thread Starter
 
Join Date: Feb 2007
Posts: 10
iTrader: (0)
 
Sputtering and dieing under 4000 rpm

It will run fine for a few minutes but once it is warmed up it will start to sputter and back fire really bad. Then if I let it drop below 4000 rpm it will just die. It will start right back up but again die if it drops. I used premium fuel from a reliable seller.
br0k3nskyy is offline  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old 11-01-2009, 04:00 PM
Simple Solutions
 
seebeeare's Avatar
 
Join Date: Jun 2008
Location: SEQUIM, WA
Posts: 965
iTrader: (3)
 
Send a message via MSN to seebeeare Send a message via Yahoo to seebeeare
Quote:
Originally Posted by br0k3nskyy View Post
It will run fine for a few minutes but once it is warmed up it will start to sputter and back fire really bad. Then if I let it drop below 4000 rpm it will just die. It will start right back up but again die if it drops. I used premium fuel from a reliable seller.
start with reg unleaded ... Trust me on this its the right choice... it burns a lot better ... used to be a premium rider myself but my ideas changed after the research...

next throw in some seafoam per instructions...

next im thinking your issue is electrical check for spark on all plugs, check ground connections and check neutral and safty switches ... how do your plugs look

im guessin u are missin on a cylinder start it up and touch the pipes see if one bank is dead....



Stator #3
MF AGM
DeGoated
Ears Shaved
R/R relocated
Rebuilt



She's worth her weight in GOLD
If u dont have it already Here is the Service Manual
How To Test the Stator
seebeeare is offline  
post #3 of 14 (permalink) Old 11-01-2009, 07:57 PM Thread Starter
 
Join Date: Feb 2007
Posts: 10
iTrader: (0)
 
I did throw some gumout in it. Ill try some new gas like you said. I did check the plugs and how they were burning, none white or black, all looked like they had been burning. Just a brown color too them. Ill check for the spark as your recommended though just incase.
br0k3nskyy is offline  
 
post #4 of 14 (permalink) Old 11-01-2009, 08:03 PM
Simple Solutions
 
seebeeare's Avatar
 
Join Date: Jun 2008
Location: SEQUIM, WA
Posts: 965
iTrader: (3)
 
Send a message via MSN to seebeeare Send a message via Yahoo to seebeeare
Quote:
Originally Posted by br0k3nskyy View Post
I did throw some gumout in it. Ill try some new gas like you said. I did check the plugs and how they were burning, none white or black, all looked like they had been burning. Just a brown color too them. Ill check for the spark as your recommended though just incase.
in a pinch i may try another additive but i will only recommend seafoam ... its the best stuff on earth ...



Stator #3
MF AGM
DeGoated
Ears Shaved
R/R relocated
Rebuilt



She's worth her weight in GOLD
If u dont have it already Here is the Service Manual
How To Test the Stator
seebeeare is offline  
post #5 of 14 (permalink) Old 11-01-2009, 08:29 PM Thread Starter
 
Join Date: Feb 2007
Posts: 10
iTrader: (0)
 
Do you just add it to the gas?
br0k3nskyy is offline  
post #6 of 14 (permalink) Old 11-01-2009, 09:01 PM
Simple Solutions
 
seebeeare's Avatar
 
Join Date: Jun 2008
Location: SEQUIM, WA
Posts: 965
iTrader: (3)
 
Send a message via MSN to seebeeare Send a message via Yahoo to seebeeare
Quote:
Originally Posted by br0k3nskyy View Post
Do you just add it to the gas?
yes but u can also add it to the oil... it has many properties that can be used ... it cleans and it stabilizes fuel it was designed originally in the marine industry



Stator #3
MF AGM
DeGoated
Ears Shaved
R/R relocated
Rebuilt



She's worth her weight in GOLD
If u dont have it already Here is the Service Manual
How To Test the Stator
seebeeare is offline  
post #7 of 14 (permalink) Old 11-01-2009, 09:23 PM
Members who have donated towards server costs
 
flitecontrol's Avatar
 
Join Date: Dec 2008
Location: Monroe, LA
Posts: 4,699
iTrader: (14)
 
To my knowledge, there is no substitute for Seafoam. Lots of look-alikes, but no substitute.

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 #8 of 14 (permalink) Old 11-02-2009, 11:32 AM
Members who have donated towards server costs
 
robardin's Avatar
 
Join Date: Jun 2008
Location: Flushing, NY
Posts: 344
iTrader: (0)
 
I have a very similar sounding issue but at a lower RPM threshold, more like around 3K RPM, and I don't remember any backfiring.

The bike has a fully charged battery and starts just fine, but after about 10 minutes of riding, no longer holds an idle. If the revs drop to around 2K it starts sputtering, and at 1K it dies and then is difficult to start up again. If I keep the engine revved to 3K at stop lights and such, I can keep it from dying, but this makes it hard for me to slow down very well ahead of them because I can only use my rear brake

However, if I let the bike sit for a while I can start it up with no problems, and ride normally for another 10 minutes before it starts having the lower-rev problems again.

It's not the battery dying (weak alternator) because the bike starts fine after sitting for a while. I checked my air filters and they're fine too.

I've had dirty carbs in the past and this doesn't seem like that. When I ride at suitable speeds, the engine is smooth, not jerky or rough, plus they're fine when I first start riding, whereas when the carbs are dirty it's apparent pretty much immediately.

I refilled it with new fuel, poured an entire can of Seafoam into the tank and took it for a ride. Still had the problem.

I checked my spark plugs, which are Iridium plugs about a year old, and they look OK. Nothing black or carbonated.

Now what? Take off the fuel petcock? -- And look for what, and do what?

"Until you have the courage to lose sight of the shore, you will not know the terror of being forever lost at sea." (Despair.com)

Last edited by robardin; 11-02-2009 at 11:34 AM.
robardin is offline  
post #9 of 14 (permalink) Old 11-04-2009, 05:52 PM Thread Starter
 
Join Date: Feb 2007
Posts: 10
iTrader: (0)
 
Checked the plugs, all are firing. Battery and alternator are fine, its starts right back up. From what i have read of the carb were clogged it would die almost immediately? Where could it lose fuel pressure from after about seven to ten minutes? If the carb is blocked would it be reasonable to assume a filter wouldnt be?
br0k3nskyy is offline  
post #10 of 14 (permalink) Old 11-04-2009, 07:47 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,644
iTrader: (4)
     
Garage
Sounds like a clogged pilot jet. Has the bike sat for awhile?

Seafoam always a good idea here.

Make sure all the clamps holding the carbs are tight, Check the airfilters and the air boxes for leaks.

Worst cas scenario here is you might have to pull the carbs to inspect and clean them...not a fun job on the 750.

KM

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker 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