Petcock position - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

 2Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 16 (permalink) Old 05-11-2020, 11:57 PM Thread Starter
Junior Member
 
Join Date: Apr 2020
Posts: 6
iTrader: (0)
 
Petcock position

Probably a stupid question, but this is my first bike with a petcock.
Do I really have to turn it off and on after and before each ride, or is it OK to just leave it on all the time? It has on, off, and reserve positions. I only use the bike at weekends.
Thanks.
LMWollen is online now  
Sponsored Links
Advertisement
 
post #2 of 16 (permalink) Old 05-12-2020, 04:26 AM
Super Moderator
 
Join Date: Feb 2013
Location: SW Florida
Posts: 2,526
iTrader: (5)
 
If the petcock is working properly, with no leakage, there is no reason to turn off for shorter periods of inactivity. if you were gonna leave the bike for a month, I would turn off. a week should be just fine.

Just to let you know, the petcock has a vacuum operated valve in it to shut off fuel when engine is not running. the off position is a manual position for turning off the fuel if needed

2005 VN750

Sold 11-27-17
michiganteddybear is online now  
post #3 of 16 (permalink) Old 05-12-2020, 07:21 AM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,786
iTrader: (4)
     
Garage
The old biker in me says its a good idea to get in the habit of turning it off after a ride, and of course remembering to turn it back on before you start it.

These bikes are getting old now, And its not uncommon to walk into your garage and find a pool of gasoline under it. It might be a small chance, but as a rider you learn not to take chances

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 #4 of 16 (permalink) Old 05-12-2020, 08:16 AM
Senior Member
 
mmart's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 424
iTrader: (1)
 
This was my first bike too, I put the bike in storage for a couple months the first year and did not shut the petcock. The first time I took it back out on the highway oil was coming out any place it could. Not knowing what was going on I took it to a mechanic. That’s how I learned that your gas tank can slowly leak into your engine. So now it’s just habit to shut it when I’m done riding for the day.
mmart is online now  
post #5 of 16 (permalink) Old 05-12-2020, 09:00 AM
Grumpy Old Man
 
Join Date: May 2020
Posts: 23
iTrader: (0)
 
I turn mine off when I’m a few streets from home in my subdivision. Then I see if I can make it into garage before I run out of gas.

With some practice I found the optimal spot to turn fuel off and not run out before I’m home.

Grumpy Old Man

Last edited by Scooter 007; 05-12-2020 at 09:19 AM.
Scooter 007 is offline  
post #6 of 16 (permalink) Old 05-12-2020, 09:52 AM
Member
 
1RadCJ5's Avatar
 
Join Date: Jun 2017
Location: So. Maine
Posts: 71
iTrader: (0)
 
MY 86 VN750 doesn't have an "OFF" position. It just has On, Reserve, and PRI which I assume is Prime. My bike can't be the only VN750 like that. My prior 86 model years ago was the same..

1986 VN750 26,000 miles
Deka AGM Battery 4-2020
All else stock, more to come thanks to VN750.com members!
1RadCJ5 is offline  
post #7 of 16 (permalink) Old 05-12-2020, 10:03 AM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 7,265
iTrader: (5)
   
On prime, the petcock is open without needing vacuum. Good setup actually. Have seen some that would run fine on prime, but not on, probably a bad petcock diaphragm.

Really have to keep an eye on these petcocks, check for a dry vacuum hose on a regular basis. Don't even use a hose clamp on mine, so I can just pop it loose.

The petcock can leak through when set to 'off', if the diaphragm is bad.

edit: With a bad diaphragm, it can leak and fill up the crankcase on any setting, with the engine off. Any gas in that hose goes straight into the front cylinder. Hose should always be dry.
1RadCJ5 likes this.

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

Last edited by Spockster; 05-12-2020 at 06:17 PM.
Spockster is offline  
post #8 of 16 (permalink) Old 05-12-2020, 11:47 AM
Member
 
1RadCJ5's Avatar
 
Join Date: Jun 2017
Location: So. Maine
Posts: 71
iTrader: (0)
 
Quote:
Originally Posted by Spockster View Post
On prime, the petcock is open without needing vacuum. Good setup actually. Have seen some that would run fine on prime, but not on, probably a bad petcock diaphragm.

Really have to keep an eye on these petcocks, check for a dry vacuum hose on a regular basis. Don't even use a hose clamp on mine, so I can just pop it loose.

The petcock can leak through when set to 'off', if the diaphragm is bad.

Good to know about the prime, Spockster. I have found in the winter, when it has been sitting for awhile, and I go to run it for 1\2 hr or so, it fires up quicker in the prime position. However, I do not even have the option to shut it off. Just reserve and on positions, other than the prime. I did inspect my fuel lines the other day. Still soft and flexible surprisingly. Also finally sucked the front brake fluid outta her reservoir. Looked like factory fluid! Sucked it out with a syringe, but didnt touch lever, so no air introduced into line. Filled up with new DOT4 fluid, and bled left side until nice and clear, and then right side until nice and clear. Old stuff dark as used motor oil, lol. New stuff is nice and clear. I can hear it thanking me now! Last night I put on 4 new NGK plastic plug thingys on end of the new plug wires that push onto spark plug. Last fall, I noticed if I touched two of them(the longer two of them), they lit me up like a light bulb! Not sure if it will affect performance or reliability, but will find out soon!

1986 VN750 26,000 miles
Deka AGM Battery 4-2020
All else stock, more to come thanks to VN750.com members!
1RadCJ5 is offline  
post #9 of 16 (permalink) Old 05-12-2020, 06:26 PM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 7,265
iTrader: (5)
   
Quote:
Originally Posted by 1RadCJ5 View Post
Good to know about the prime, Spockster. I have found in the winter, when it has been sitting for awhile, and I go to run it for 1\2 hr or so, it fires up quicker in the prime position. However, I do not even have the option to shut it off. Just reserve and on positions, other than the prime. I did inspect my fuel lines the other day. Still soft and flexible surprisingly. Also finally sucked the front brake fluid outta her reservoir. Looked like factory fluid! Sucked it out with a syringe, but didnt touch lever, so no air introduced into line. Filled up with new DOT4 fluid, and bled left side until nice and clear, and then right side until nice and clear. Old stuff dark as used motor oil, lol. New stuff is nice and clear. I can hear it thanking me now! Last night I put on 4 new NGK plastic plug thingys on end of the new plug wires that push onto spark plug. Last fall, I noticed if I touched two of them(the longer two of them), they lit me up like a light bulb! Not sure if it will affect performance or reliability, but will find out soon!
The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.

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 #10 of 16 (permalink) Old 05-12-2020, 09:55 PM
Senior Member
 
MSattler's Avatar
 
Join Date: Jun 2019
Location: Iowa
Posts: 259
iTrader: (0)
 
Quote:
Originally Posted by Spockster View Post
The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.
I got mine from dennis kirk. like $8 total including wires.

'08 Road King Classic
'86 VN750:
Ear Shave, K&N Filters, Mean Streak Seat, AGM battery, Blue Wire Mod, Pick-up Coil Mod, Timing Advance Mod, NGK Iridium Plugs and Wire, LEDs, Bed Liner Paint Job, Over-sized Tires, New Brakes, New Fork Seals, Progressive Springs, Kick Stand Mod, Highway Pegs, 40/140 No Shims, Vance & Hines Exhaust, New Grips, Extra Wide Emgo Handle Bars
John 8:44, REV 2:9, REV 3:9 - If you were kicked out of 109 bars, would you think the problem was you, or the 109 bars?
MSattler 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