Throttle takes a second to drop when I let off the gas - 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 51 (permalink) Old 05-06-2012, 11:54 PM Thread Starter
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
Throttle takes a second to drop when I let off the gas

I just re-assembled my bike. The carbs are actually a different set setup for an Earshave. They are 141/F, 142/R, 40 Pilots. Supposedly they were chem dipped prior to clean them.

Idle is also a bit rough below 1400rpm

I am thinking something is a little sticky inside the carbs. With some SeaFoam I think it will clear up.

Any thoughts?

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

Last edited by thtanner; 05-06-2012 at 11:56 PM.
thtanner is offline  
Sponsored Links
Advertisement
 
post #2 of 51 (permalink) Old 05-07-2012, 12:07 AM
Senior Member
 
Join Date: Mar 2012
Posts: 450
iTrader: (0)
 
Garage
Disconnet the throttle cables at the carb. Then move the throttle linkage to full then let go, it should snap back. Then try it at different positions. If it always snap back, then one or both of the cables may be worn, or dirty. Most likely it is a cable.
Rebel13 is offline  
post #3 of 51 (permalink) Old 05-07-2012, 12:22 AM Thread Starter
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
Prior to dis-assmbly everything was muy bueno. The throttle snaps back quickly with the cables on, and off. It couldn't hurt to lube the cables, and play with adjustments some more.

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 #4 of 51 (permalink) Old 05-07-2012, 09:20 AM
Senior Member
 
Join Date: Mar 2010
Location: jacksonville, fl
Posts: 335
iTrader: (1)
 
check your routing, lube them up with wd-40 and re assemble. it sounds like they are binding up on you.

Harley sportster fenders
custom raked front end
custom exhaust
vn800 tank and guages
modified seat and recovered
rear frame chopped
custom wiring harness
airbox removed
hzhardy is offline  
post #5 of 51 (permalink) Old 05-07-2012, 10:39 AM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,681
iTrader: (4)
     
Garage
SeaFoam always is a good start.

However, if the linkage is snapping back but the revs are not falling back with it, you might have a sticking diaphragm. This can be caused by improper installation, a clogged vent hole, or a tiny tear in the diaphragm itself.

Likely just a clog in the diaphragms vent hole....not sure if SeaFoam would help this.

Other cause could be a small air leak from a carb boot.

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker is offline  
post #6 of 51 (permalink) Old 05-07-2012, 11:50 AM Thread Starter
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
Quote:
Originally Posted by Knifemaker View Post
However, if the linkage is snapping back but the revs are not falling back with it, you might have a sticking diaphragm.
The carb boots and cables check out, so I'll inspect the diaphragm and see what's up. Cheers

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 #7 of 51 (permalink) Old 05-07-2012, 12:23 PM
Crap, I WAS in 5th gear.
 
Join Date: Sep 2011
Location: So. Cal
Posts: 500
iTrader: (1)
 
Rule out what you can mechanically before removing the carbs again. Check the air cut-off valves (also knows as coasting enrichers) and passages. I have a 2001 and one of my enricher diaphragms had pinholes at 35,000 miles.
Kelly2001 is offline  
post #8 of 51 (permalink) Old 05-07-2012, 01:09 PM
romeobravo172
 
romeobravo172's Avatar
 
Join Date: Nov 2011
Location: Leesburg,Fl
Posts: 842
iTrader: (18)
 
Send a message via Skype™ to romeobravo172
Kelly, where are the cut off valves? aka coasting enrichers, one of my 04's does that also.

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 #9 of 51 (permalink) Old 05-07-2012, 01:21 PM
Crap, I WAS in 5th gear.
 
Join Date: Sep 2011
Location: So. Cal
Posts: 500
iTrader: (1)
 
Coasting Enricher

Quote:
Originally Posted by romeobravo172 View Post
Kelly, where are the cut off valves? aka coasting enrichers, one of my 04's does that also.
They are under covers on the sides of the carbs. One of the mounting screws is used when checking float height. The are kind of expensive, so you shouldn't just replace them willy-nilly. The rubber on mine had deteriorated and the inner fabric was visible. I remember being able to access them with the carbs installed. It got to the point where I had to drag the engine down with the clutch at stoplights. I had a lot of afterfiring (in the exhaust) during deceleration too, as faulty diaphragms cause a lean mixture when letting off the throttle.
Kelly2001 is offline  
post #10 of 51 (permalink) Old 05-07-2012, 01:41 PM Thread Starter
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
Thanks for all the advice everyone.

I am going to try to inspect them at lunch, and steal the good diaphragm from my other set of carbs if needed. I'll update this thread with any findings.

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  
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