Leaking fuel from intake and dead cylinder - 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 8 (permalink) Old 01-23-2012, 11:37 PM Thread Starter
Member
 
Join Date: Sep 2010
Location: Olympia, WA
Posts: 34
iTrader: (0)
 
Leaking fuel from intake and dead cylinder

So I have a 91 vn750. Did some engine work an finally got it all back together. I have cobra pipes and earshave, with 38 pilots and 140 main jets. Carbs have been completely rebuilt, all new parts. The bike will start and run if holding the throttle slightly open. I am leaking an abnormal amount of fuel from the front cylinder carb from where the air filter connects. Looks like it may be starting to come out where the 3 holes on the bottom of the opening are. The rear cylinder also seems to not be firing completely. The front pipe gets very hot while rear cylinder only gets somewhat warm. Not sure what is causing these problems or where to go from here. Also, the rear spark plugs have gas on them so I think its getting fuel. The front cylinder plugs have plenty of gas on them and are fairly dark and wet (carbon buildup).

Things I have done...
Complete carb rebuild including choke parts, enrichers, needles, jets, etc
Cleaned spark plugs-checked good spark at all 4 cylinders
Checked timing...just fine
Petcock rebuild kit
Fresh gas and seafoam

I have done a few others things but other than the obvious i am not sure what to check. I am not sure if any one has had these problems or know what i should check next. Please give any and all suggestions. Thank in advance.
yukonjon is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 01-23-2012, 11:57 PM
romeobravo172
 
romeobravo172's Avatar
 
Join Date: Nov 2011
Location: Leesburg,Fl
Posts: 842
iTrader: (18)
 
Send a message via Skype™ to romeobravo172
Will let some tec people chime in here, but keep an eye on oil level, will almost bet you are getting fuel into oil!!

04-3,200 miles bought July 2011 with 928 miles. Loaded with acessories to many to list here, see my albums for more details! I also make a custom tank bib specific for the 750 if anyone is interested, ck my albums for some pics.
romeobravo172 is offline  
post #3 of 8 (permalink) Old 01-24-2012, 08:15 AM
Members who have donated towards server costs
 
JM2001's Avatar
 
Join Date: Mar 2011
Location: Rochester, New York
Posts: 1,803
iTrader: (1)
 
Quote:
Originally Posted by yukonjon View Post
So I have a 91 vn750. Did some engine work an finally got it all back together. I have cobra pipes and earshave, with 38 pilots and 140 main jets. Carbs have been completely rebuilt, all new parts. The bike will start and run if holding the throttle slightly open. I am leaking an abnormal amount of fuel from the front cylinder carb from where the air filter connects. Looks like it may be starting to come out where the 3 holes on the bottom of the opening are. The rear cylinder also seems to not be firing completely. The front pipe gets very hot while rear cylinder only gets somewhat warm. Not sure what is causing these problems or where to go from here. Also, the rear spark plugs have gas on them so I think its getting fuel. The front cylinder plugs have plenty of gas on them and are fairly dark and wet (carbon buildup).

Things I have done...
Complete carb rebuild including choke parts, enrichers, needles, jets, etc
Cleaned spark plugs-checked good spark at all 4 cylinders
Checked timing...just fine
Petcock rebuild kit
Fresh gas and seafoam

I have done a few others things but other than the obvious i am not sure what to check. I am not sure if any one has had these problems or know what i should check next. Please give any and all suggestions. Thank in advance.
Are you sure of your description? You say the front cylinder is leaking gas and runs hot. It is running very rich and should be cooler. You say the rear cylinder is running hot which would be from a lean condition, but you say the plugs are dark and wet which means running rich. I would think that you have a float problem in each carb. I would also put in new iridium plugs, check the plug wires and boots for leaks, and make sure the battery is strong. Also the air/fuel mixture screws should be adjusted to your new jets.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
JM2001 is offline  
 
post #4 of 8 (permalink) Old 01-24-2012, 09:11 AM Thread Starter
Member
 
Join Date: Sep 2010
Location: Olympia, WA
Posts: 34
iTrader: (0)
 
Description is correct. Thats kinda why im stuck in what to do. Mixture screws are about 2.5 turns out. While troubleshooting yesterday had something interesting happen. Had the spark plug and wire removed from the left side on the rear cyclinder to check spark. Cranked the eng quickly and it started up and ran better than I had seen since rebuild with no sparkplug installed. Seems like the front cylinder might be doing a lot of the work. It is definitely the front cylinder running completely at the same time as leaking fuel though. I think i may have 2 separate problems. One being the leak and the other being the rear cylinder. The front cylinder is the one running rich (dark black plugs). Rear plugs look fairly normal. Have you guys been able to source plugs from a common store (autozone, napa, etc) instead of ordering. Thanks for the help. I really need to figure this thing out. Too much money already invested.
yukonjon is offline  
post #5 of 8 (permalink) Old 01-24-2012, 10:02 AM
Members who have donated towards server costs
 
flitecontrol's Avatar
 
Join Date: Dec 2008
Location: Monroe, LA
Posts: 4,697
iTrader: (14)
 
I got my iridiums at O'Riley. Most stores can order them if they don't have them in stock.

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 #6 of 8 (permalink) Old 01-24-2012, 10:14 AM
Members who have donated towards server costs
 
Join Date: Nov 2007
Location: Chandler, Arizona
Posts: 2,848
iTrader: (0)
 
There should not be fuel leaking from either one of your carbs. If fuel is leaking from the carb inlet, then it is also most likely leaking into the cylinders as well. Either the float levels are not set right (if they can be adjusted, I don't remember) or the needle valves are leaking. There are a couple of other possible issues with floats. They could have a leak and filled up with gas, or they could be rubbing on the side of the float bowl (that one happened to me once)

Other than the carb or the ignition, there is nothing easy to fix that I can think of that could be wrong with the rear cylinder.

You can buy those plugs at most auto parts stores, and if they don't have them, any Japanese bike dealer will.

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 8 (permalink) Old 01-24-2012, 01:41 PM
Members who have donated towards server costs
 
JM2001's Avatar
 
Join Date: Mar 2011
Location: Rochester, New York
Posts: 1,803
iTrader: (1)
 
Got my iridiums at Advance Auto for $6.99 each.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
JM2001 is offline  
post #8 of 8 (permalink) Old 01-24-2012, 02:45 PM Thread Starter
Member
 
Join Date: Sep 2010
Location: Olympia, WA
Posts: 34
iTrader: (0)
 
I'll pick up some new plugs and double check my needles. Maybe they are seated right. To be sure, does the shorter needle go in front or back. Wanna make sure they are correct. I think I remembered seeing something about the yellow plastic clip going on top of the needle had to be in a certain way. Is this true. After that I'll go with the floats. May the rear cylinder is normal and the front is the one all screwed up.
yukonjon is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Tags
fuel , intake , leak

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