Help!! Unknown Problem - 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 10-02-2016, 12:01 PM Thread Starter
Junior Member
 
Join Date: Jul 2016
Posts: 12
iTrader: (0)
 
Help!! Unknown Problem

My bike was running great until midsummer. Then my stator took a crap. With all the wonderful help from browsing on here I was able to change it with one from TPE and also installed a MOSFET R/R. It charges approx 14.5 volts at all rpms now and runs great when cold or lower rpms.
However, when the bike is thoroughly warmed up it will spit, sputter and pop at higher rpms especially when accelerating at full throttle. I have tried back blowing the carbs, turned the screws on the carbs out 3 turns and marbled it to see if it made any difference. I took it for a ride last night and when cold no popping, but when warmed up popping like crazy when coasting and still the problems at high rpms, above 6k. No voltage change when warmed up so I'm leaning towards a carb problem, but what? I can't detect a carb boot leak, i used propane and no change in idle speed. I used new crush gaskets for the exhaust, but dont think it could be that. Please help I getting frustrated. Thanks for any help.
Clifford Waltz is offline  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old 10-02-2016, 12:15 PM
FREEBIRDS MC CENTRAL NY
 
OleDirtyDoc's Avatar
 
Join Date: May 2011
Location: Norwich,NY
Posts: 15,843
iTrader: (0)
     
Garage
Send a message via Yahoo to OleDirtyDoc
how long did it sit and did ya drain the fuel outta the carb bowls?sounds like dirty carb syndrome to me😞

Sent from my LGL34C using Tapatalk

ONE RATS ASS GIVEN PER POST
Support your local FREEBIRDS MC
1986/5 Vn700/750 Frankenfook cross eyed bitch "Mellisa Fayhe"
I am a BIKER and i'm proud.FREEBIRDS MC CENTRAL NY

lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
OleDirtyDoc is offline  
post #3 of 14 (permalink) Old 10-02-2016, 12:59 PM Thread Starter
Junior Member
 
Join Date: Jul 2016
Posts: 12
iTrader: (0)
 
It sat for about a month, i have run 3-4 tanks of fuel through it since getting it running. I had put Sea Foam in the first tank, maybe I need to try more of that. Yes I did drain the carb bowls when I back blew them. Thanks for the suggestion though
Clifford Waltz is offline  
 
post #4 of 14 (permalink) Old 10-02-2016, 01:42 PM
FREEBIRDS MC CENTRAL NY
 
OleDirtyDoc's Avatar
 
Join Date: May 2011
Location: Norwich,NY
Posts: 15,843
iTrader: (0)
     
Garage
Send a message via Yahoo to OleDirtyDoc
did you drain the bowls before it sat?

Sent from my LGL34C using Tapatalk

ONE RATS ASS GIVEN PER POST
Support your local FREEBIRDS MC
1986/5 Vn700/750 Frankenfook cross eyed bitch "Mellisa Fayhe"
I am a BIKER and i'm proud.FREEBIRDS MC CENTRAL NY

lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
OleDirtyDoc is offline  
post #5 of 14 (permalink) Old 10-02-2016, 02:12 PM Thread Starter
Junior Member
 
Join Date: Jul 2016
Posts: 12
iTrader: (0)
 
No I didn't. I didn't plan on it sitting for that long, TPE took awhile to get my stator back to me.
Clifford Waltz is offline  
post #6 of 14 (permalink) Old 10-04-2016, 02:14 PM Thread Starter
Junior Member
 
Join Date: Jul 2016
Posts: 12
iTrader: (0)
 
OK, I filled the carb bowls with sea foam and left them sit for about 2 days. I drained the sea foam out, back blew them again and took it for a ride. Once the remaining sea foam burnt up it was running exactly the same. Sputtering and popping at full throttle above 6k rpms and excessive popping when coasting despite marbling and turning the air screws out 3 turns. Could this be a mild case of fuel starvation, when I got done I could hear the fuel tank whistling? Otherwise the bike runs great, accelerates good until higher rpms, cruises at highway speed easily and idles at 1100 rpms without a problem. Any help will be appreciated. Thanks
Clifford Waltz is offline  
post #7 of 14 (permalink) Old 10-05-2016, 06:09 PM
Senior Member
 
kc2dgq's Avatar
 
Join Date: May 2010
Location: New Jersey
Posts: 3,350
iTrader: (13)
 
Garage
POOGS....Phantom Out Of Gas Syndrome.

Check your fuel tank vent to ensure it is not clogged. The nipple under the tank cap hinge leads out to the rear of the tank(under the seat) and a hose will be attached that drops down to underneath the bike (open to atmosphere). Check that you can get air all the way through that passage and out the bottom ( of shoot some carb cleaner down that nipple and see if it drips out the hose).

A whistle in the tank cap usually means air is struggling to get air in the tank to replace the fuel volume as the fuel leaves the tank. If the vent line is clear, your cap is the issue.

I took apart the tank cap on mine a few years ago and removed the diaphragm. Never had the whistle or POOGS again.
kc2dgq is offline  
post #8 of 14 (permalink) Old 10-05-2016, 07:35 PM
I'm a rider
 
One1's Avatar
 
Join Date: May 2014
Location: Signal Mountain, TN
Posts: 753
iTrader: (0)
 
Garage
There could still be voltage issues from resistance when the RR is hot. Check the plug at the RR to see if it is overly hot on any pins after the bike is warmed up. One of my Vulcans would backfire like a gunshot when the RR warmed up and it wasn't getting good spark. Dumped too much fuel to burn off with a weak spark and shot fire everywhere I went. I noticed I was getting a lot of resistance on the pins when they got hot and it caused a voltage drop. Using better connectors I was able to eliminate the issue and the gunfire. These bikes are heavily dependent on voltage compared to some bikes. It went from popping like crazy to smooth as butter. There are 6 pins on that RR and ANY of them could have a voltage drop. Always measure at each pin at the RR, the rest of the bike could be fine on voltage. No less than 6 times I have rebuilt the carbs for a running issue that turned out to be voltage related instead.


1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

Engineering solutions for the VN750 Community.

Last edited by One1; 10-05-2016 at 07:38 PM.
One1 is offline  
post #9 of 14 (permalink) Old 10-05-2016, 08:47 PM Thread Starter
Junior Member
 
Join Date: Jul 2016
Posts: 12
iTrader: (0)
 
Thanks for the info on voltage. I cleaned my gas cap and tore a chunk out of the red rubber piece (diaphragm), is it safe to run without it? I will have to check the R/R. I am no means an electrician, I used the kit came with the plugs for the R/R, I used 12 guage wire from the stator and then 8 guage to my battery. I'm pretty sure anyhow. I only crimped the connections as I didn't have a soldering iron, now that I have one I need to practice soldering before I redo the wiring. Looks like I still have some work to do checking all the voltages Thank you very much for this info.
Clifford Waltz is offline  
post #10 of 14 (permalink) Old 10-05-2016, 10:42 PM
I'm a rider
 
One1's Avatar
 
Join Date: May 2014
Location: Signal Mountain, TN
Posts: 753
iTrader: (0)
 
Garage
You may see some seeping when riding as it sloshes, no issues with pressure as you can run the bike off a solo cup with a fuel hose stuck in the bottom.


1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

Engineering solutions for the VN750 Community.
One1 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