Air cut valve question - 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 7 (permalink) Old 05-12-2012, 01:44 PM Thread Starter
Member
 
Join Date: May 2012
Posts: 33
iTrader: (0)
 
Air cut valve question

Hi all!!

New member here. Been reading around here for awhile but just joined. Lots of good info here!!

Anyway, I have a question that I hope someone can help me out with. I bought a 2002 Vulcan 750 last year. It has about 10k miles on it.

The engine was running rich. I checked the air cut off valves and the plungers were stuck in the bores and the diaphrams were hard and cracked (leaking). I bought a set of air cut off valves (aftermarket brand) and installed them. Initially it ran great. Then, the rear cylinder started running rough (too rich). I pulled the air cut valve back off and found gas in the vacuum side of the diaphram. So, it's gotta be leaking. Maybe I got bad ones? Anyway, I wanted to ride so I blocked off the vacuum to the air cut off valves and it's running great. A little more popping from the exhaust but nothing bad.

I'm getting ready for a week long trip on the bike and will ride about 1000 miles total.

Are there any negative side effects to blocking the air cut valves??




Thanks in advance for any help/advise!!!
vulcanguy is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 05-12-2012, 02:38 PM
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
How much play did the metal plunger part have when u inserted it? It should have been somewhat snug with little play.

Does the size look right, etc?

I had mine out recently, and found them to be quite snug to slide in and out (but smooth if you were at a perfect angle)

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
thtanner is offline  
post #3 of 7 (permalink) Old 05-12-2012, 08:05 PM Thread Starter
Member
 
Join Date: May 2012
Posts: 33
iTrader: (0)
 
Quote:
Originally Posted by thtanner View Post
How much play did the metal plunger part have when u inserted it? It should have been somewhat snug with little play.

Does the size look right, etc?

I had mine out recently, and found them to be quite snug to slide in and out (but smooth if you were at a perfect angle)


Thanks for the reply!

They looked just like the ones that came out. The new ones were snug but moved freely. The old ones were seized in the bores.

I can't see any pinholes in the diaphram but gas is getting past and into the vacuum port, causing it to run rich...especially at idle.
vulcanguy is offline  
 
post #4 of 7 (permalink) Old 05-12-2012, 09:00 PM
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
Both sides or just one?

If just one, switch them around and see what happens?

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
thtanner is offline  
post #5 of 7 (permalink) Old 05-12-2012, 11:11 PM Thread Starter
Member
 
Join Date: May 2012
Posts: 33
iTrader: (0)
 
It runs great without them so will it hurt anything to run about 1000 miles without them functioning??
vulcanguy is offline  
post #6 of 7 (permalink) Old 05-13-2012, 05:14 PM
Crap, I WAS in 5th gear.
 
Join Date: Sep 2011
Location: So. Cal
Posts: 500
iTrader: (1)
 
It may heat up your exhaust valves. If you're going to do it, screw out your idle bleeds to compensate a little. The biggest effects would be popping in your exhaust, and less engine braking.
Kelly2001 is offline  
post #7 of 7 (permalink) Old 05-13-2012, 08:02 PM Thread Starter
Member
 
Join Date: May 2012
Posts: 33
iTrader: (0)
 
Thanks for the info!!!!
vulcanguy 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