Engine flooding with gas. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

 3Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 26 (permalink) Old 08-14-2017, 04:57 PM Thread Starter
Member
 
wmdaricthompson's Avatar
 
Join Date: Aug 2016
Location: Pittsburgh PA
Posts: 39
iTrader: (0)
 
Garage
Engine flooding with gas.

Hi all,

Need some help with my 93 Vulcan 750. I've always been in awe of the vast amount of experience and knowledge on forums, and I've gotten as far as I have on this bike by being a lurker here, but I need some direct help now if anyone can spare it. I bought it from someone who didn't know a lot about working on bikes, but was gung-ho about doing so anyway. I keep finding little time bombs from him.

I've got it running at this point, but it runs absurdly rich. As in, gas vapor out the exhaust rich. I've meticulously cleaned the carbs, the floats are set right (and verified to be right with tube from the drain screw). The fuel petcock seems to be functioning normally (I've primed it several times with my mouth, I can see gas flowing until at some point it just stops, no gas leaking out anywhere). Gas is getting into the engine in excess, somehow, but I can't figure it out. I'm getting miserable mileage (like... 20ish miles per gallon), and the plugs are fouling within 20 miles or so. The bike starts to skip, once I brush the plugs off with a stiff bristle brush, it's back to running normally. The first time I did an oil change, there was a large liquid volume, and the oil smelled like gas. The main jet holders were smashed and holes in the side were closed off from that when I got the bike, and the coaster enricher diaphragms were garbage. Replaced those both in hopes it would make a difference, but it doesn't seem to have. I'm not averse to rebuilding the petcock, but it doesn't seem like it needs it right now (I've seen that as advice to cure a rich condition many times while lurking).

The bike is marbled, has stock exhaust, has the stock jets (unless they have been drilled).

I'm tearing my hair out with this problem, please help!

1993 Kawasaki Vulcan 750

Garage is good. Garage is Therapy. Garage is life.
wmdaricthompson is offline  
Sponsored Links
Advertisement
 
post #2 of 26 (permalink) Old 08-14-2017, 05:06 PM Thread Starter
Member
 
wmdaricthompson's Avatar
 
Join Date: Aug 2016
Location: Pittsburgh PA
Posts: 39
iTrader: (0)
 
Garage
Quote:
Originally Posted by wmdaricthompson View Post
The main jet holders were smashed and holes in the side were closed off from that when I got the bike
This is what I am referring to here. I am at a loss as to how the PO accomplished this devastation, so if you have a suggestion to fix something that it would have taken an idiot to do... he fits the bill.

(New jet holders shown with old destroyed ones)
Attached Thumbnails
Click image for larger version

Name:	Main jet holders.jpg
Views:	165
Size:	96.3 KB
ID:	40521  

1993 Kawasaki Vulcan 750

Garage is good. Garage is Therapy. Garage is life.
wmdaricthompson is offline  
post #3 of 26 (permalink) Old 08-15-2017, 12:52 AM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,338
iTrader: (5)
   
Pull the vacuum line from the petcock and let it sit with the petcock on, engine off. Check over time to see if the vacuum port of the petcock gets wet with gas. Leak through the vacuum port only affects front cylinder.

Wow, those jets are really hammered. Do the centers look to have been drilled out at all? Just wondering if someone drilled the jets while still in the carb, and drilled a carb passage too?. Or how they got bent like that. Compare centers of new vs. old jets. What are the numbers on the new jets? Stock is 138 main and 38 pilot.

Did you elongate the emulsion holes to open them, or were they like that already?

Assuming the float height is correct, and the petcock is not leaking through the vacuum port, for now I'm left wondering why it's flooding so bad.

Is the carb body cracked? Maybe check close around where the jets are.

A float filling with gas should show up in the float height check, unless float height was checked immediately after assembly when the float was still dry. Same with a stuck float, unless it stuck after the float height was checked.

Do you think there's any chance a float is stuck now? Re-check float height? It's a somewhat fine line from low to high levels.

Sounds like it's in both carbs? Affecting all the plugs? Have you gone back into the carbs to check? Make sure the tips of the needles are ok and the floats don't have gas in them .... Remove float and shake it as soon as the carb comes off.

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 #4 of 26 (permalink) Old 08-15-2017, 09:04 AM
Senior Member
 
ubertalldude's Avatar
 
Join Date: Jun 2016
Location: NE Florida
Posts: 643
iTrader: (0)
 
Quote:
Originally Posted by wmdaricthompson View Post
Hi all,

The bike is marbled, has stock exhaust, has the stock jets (unless they have been drilled).
I can't imagine any other way the holders got so smashed like that unless the PO was in there plinkin' around where he OBVIOUSLY ought not to have been

New jets aren't too expensive, Your Keihin-Mikuni Jets Store-Pjmotorsports.Com ships pretty quick, too

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 online now  
post #5 of 26 (permalink) Old 08-15-2017, 10:21 AM Thread Starter
Member
 
wmdaricthompson's Avatar
 
Join Date: Aug 2016
Location: Pittsburgh PA
Posts: 39
iTrader: (0)
 
Garage
Quote:
Originally Posted by Spockster View Post
Pull the vacuum line from the petcock and let it sit with the petcock on, engine off. Check over time to see if the vacuum port of the petcock gets wet with gas. Leak through the vacuum port only affects front cylinder.
I'll give this a try for the sake of giving it a try, but I don't think it's going to be my issue since I'm getting plug fouling in both cylinders. (Who knows though, I may have multiple issues. Front cylinder is definitely fouling worse)

Quote:
Originally Posted by Spockster View Post
Wow, those jets are really hammered. Do the centers look to have been drilled out at all? Just wondering if someone drilled the jets while still in the carb, and drilled a carb passage too?. Or how they got bent like that. Compare centers of new vs. old jets. What are the numbers on the new jets? Stock is 138 main and 38 pilot.

Did you elongate the emulsion holes to open them, or were they like that already?
I haven't picked up new jets, just the new holders. The jets themselves looked pretty unmolested, a little bit of screwdriver damage is all. The jets in the bike are 132 main, 38 pilot. I've seen 132, 135, and 138 all listed as stock size for the bike, since I'm already running way rich and on the smallest "stock" jet, I'll probably leave these at 132 if I replace them just for the sake of replacing them. The main jet holders are exactly as I found them when I pulled them from the bike. They looked way too damaged to be reused so I just replaced them without trying to fix. I can't see any kind of excessive damage on the inside of where the main jet holder sits that could have been caused by an errant drill bit.

Quote:
Originally Posted by Spockster View Post
Assuming the float height is correct, and the petcock is not leaking through the vacuum port, for now I'm left wondering why it's flooding so bad.

Is the carb body cracked? Maybe check close around where the jets are.
Yeah, you and me both. I've been banging my head off the wall on this for weeks now. The top of one of the carb float chambers does have a small crack, but it holds liquid without drips unless I pry the crack open by pulling on the carb on either side (and even then, it barely seeps). I was very concerned about it for a quick minute, then I noticed that it's right near the vent port anyway, so it should be dry on the inside against it as it is. I definitely do think that crack is a problem, but I don't think it's contributing to my rich symptoms.

Quote:
Originally Posted by Spockster View Post
A float filling with gas should show up in the float height check, unless float height was checked immediately after assembly when the float was still dry. Same with a stuck float, unless it stuck after the float height was checked.

Do you think there's any chance a float is stuck now? Re-check float height? It's a somewhat fine line from low to high levels.
I'll recheck today to be sure, but they were sitting right where I wanted them before (per the service manual)

Quote:
Originally Posted by Spockster View Post
Sounds like it's in both carbs? Affecting all the plugs? Have you gone back into the carbs to check? Make sure the tips of the needles are ok and the floats don't have gas in them .... Remove float and shake it as soon as the carb comes off.
Tips of the needles are ok, no ridges or lines. They look good and smooth with no dimpling or rounded point. I've had the carbs off several times now and never noticed gas in them.

Thank you so much for responding, I appreciate the advice on where to look for this. I'm pretty much totally stymied at this point. It really weirded me out when, with the choke off, fuel mix screws ALL the way in, and throttle shut, this bike would run. Gas is coming from somewhere it shouldn't for sure, but I can't figure it out.

1993 Kawasaki Vulcan 750

Garage is good. Garage is Therapy. Garage is life.
wmdaricthompson is offline  
post #6 of 26 (permalink) Old 08-15-2017, 10:26 AM Thread Starter
Member
 
wmdaricthompson's Avatar
 
Join Date: Aug 2016
Location: Pittsburgh PA
Posts: 39
iTrader: (0)
 
Garage
Quote:
Originally Posted by ubertalldude View Post
I can't imagine any other way the holders got so smashed like that unless the PO was in there plinkin' around where he OBVIOUSLY ought not to have been

New jets aren't too expensive, Your Keihin-Mikuni Jets Store-Pjmotorsports.Com ships pretty quick, too

I've had good experiences with them in picking up my enricher diaphragms. I'll either pick up from them, or I'll just add them in to a Partzilla order I have brewing for another bike so I only have to pay one shipping charge (price is about the same).

I'm with you though on "how the heck did he do that??". If he managed to do that to them while they were in the carbs, very good chance he hurt the carbs. Part of me is honestly tempted to just go pick up a new rack of carbs for the bike. There is a cycle recycling place nearby that sells them for about $75 each. I'd have to clean them up again, but if he's damaged these carbs internally, it's the only way I'd get my issue fixed.

1993 Kawasaki Vulcan 750

Garage is good. Garage is Therapy. Garage is life.
wmdaricthompson is offline  
post #7 of 26 (permalink) Old 08-15-2017, 10:33 AM
Senior Member
 
ubertalldude's Avatar
 
Join Date: Jun 2016
Location: NE Florida
Posts: 643
iTrader: (0)
 
Quote:
Originally Posted by wmdaricthompson View Post
Gas is coming from somewhere it shouldn't for sure, but I can't figure it out.
what about the chokes?

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 online now  
post #8 of 26 (permalink) Old 08-15-2017, 10:35 AM Thread Starter
Member
 
wmdaricthompson's Avatar
 
Join Date: Aug 2016
Location: Pittsburgh PA
Posts: 39
iTrader: (0)
 
Garage
Quote:
Originally Posted by ubertalldude View Post
what about the chokes?
Chokes appeared to move smoothly with no apparent damage to the mechanisms when I removed them to inspect. They retracted fully and on their own with no sticking.

1993 Kawasaki Vulcan 750

Garage is good. Garage is Therapy. Garage is life.
wmdaricthompson is offline  
post #9 of 26 (permalink) Old 08-15-2017, 10:54 AM
2014 KLR 650!
 
Goofyfoot2001's Avatar
 
Join Date: Jun 2013
Location: Tega Cay, SC
Posts: 3,355
iTrader: (1)
 
OMG, did you put the hammer down? Literally?

2014 Kawasaki KLR 650
Back to the Kawa World
Goofyfoot2001 is offline  
post #10 of 26 (permalink) Old 08-15-2017, 10:59 AM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,338
iTrader: (5)
   
I'm wondering if someone stuck the smaller jets in there trying to correct the flooding.

I keep thinking someone tried a custom hack and did it to both carbs. Which would mean you need a couple of carbs. Longshot for both carbs to flood the same way.

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