Hard to start when motor's warm -Help - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
VN750 General Discussion

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 15 (permalink) Old 11-24-2011, 01:12 AM Thread Starter
Member
 
92' Vulcan Rider's Avatar
 
Join Date: Nov 2011
Location: Santa Barbara CA
Posts: 30
iTrader: (0)
 
Hard to start when motor's warm -Help

After I get to my destination and try to start it up to leave it doesn't like to start. It just back fires. Even just going to the local grocery store and back. The warmer the motor is (the longer the ride) the harder it is to start. It starts great cold. Please help. Thanks
92' Vulcan Rider is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old 11-24-2011, 02:34 AM
If only it had 6th gear..
 
DavesVulster's Avatar
 
Join Date: Jul 2011
Location: North of Boston
Posts: 1,100
iTrader: (1)
 
There's a bunch of posts on this. Do a search for hot starting problem and you'll find a slew of info.
The link below talks about the pick up coil mod which is probably what you're in need of. Good luck.
https://www.vn750.com/forum/archive/i...hp/t-1167.html

Dave

Mods:
Jetted, shaved & coastered
Home made under-tank single filter
Converted ACCT's to manual (thanks wib714)
Dual vac lines on petcock (my cure for ticking)
LED tail/plate lights
Relocated helmet lock to license plate

Added stuff:
Customized hard bags w/ lights
Chrome levers
Hellcat windscreen
LED running lights
Home made 'Vita-Volt' meter
Foot rests on engine guard
Tunes

Hmm....she was on the back when we left.... ??
DavesVulster is offline  
post #3 of 15 (permalink) Old 11-24-2011, 02:46 AM Thread Starter
Member
 
92' Vulcan Rider's Avatar
 
Join Date: Nov 2011
Location: Santa Barbara CA
Posts: 30
iTrader: (0)
 
Thanks Dave
92' Vulcan Rider is offline  
 
post #4 of 15 (permalink) Old 11-24-2011, 07:22 AM
Senior Member
 
kc2dgq's Avatar
 
Join Date: May 2010
Location: New Jersey
Posts: 3,350
iTrader: (13)
 
Garage
I did the Pickup coil clearance mod in hopes of fixing this issue but it did not completely fix the issue.
First off, I would check your battery and have it load tested.
It could be that your battery is weak. The other thing I found was that by turning the bike off via the kill switch on the handlebar BEFORE turning off the ignition with the key will help since it will disable the headlight until the bike is running, therefore removing the load of the headlight while trying to start the bike.
Good luck! let us know what works for you.
kc2dgq is offline  
post #5 of 15 (permalink) Old 11-24-2011, 08:49 AM
Old Twistie Sticks Rider
 
Old Dog's Avatar
 
Join Date: Aug 2007
Location: Country Created by Geniuses, But Run by Idiots...!!!
Posts: 5,072
iTrader: (2)
 
Quote:
Originally Posted by kc2dgq View Post
The other thing I found was that by turning the bike off via the kill switch on the handlebar BEFORE turning off the ignition with the key will help since it will disable the headlight until the bike is running, therefore removing the load of the headlight while trying to start the bike.
Don't tell me that now... lol, I have always put a toggle switch on my head light to kill the power to it on start up... I'll try that and see if it will work on my present bike...
Have a good one...Old Dog...

Southern Central Tennessee.......
Now on the Dark Side......
Girl's Bike 09 Sporty xl 1200 Custom...33k + & clickin......
Sportster Owner/Rider since age 72...lol... Rider since Simplex...???
09-xl1200 "C" Vivid Black, Cast wheels w/19" Frt., SE-Stage 1+, X14iEDs...
MicroTach +, Higher wider H-bars, GPS Mt., Mustach bar Hwy. pegs...
Viking Shock cutout Saddlebags, Rear Mt. Signal Lt. Kit, Fork Brace...
RoadKing Air Shocks, Mustang Seat, Progressive Fork Springs...
Old Dog is offline  
post #6 of 15 (permalink) Old 11-24-2011, 10:44 AM
Members who have donated towards server costs
 
Join Date: Nov 2007
Location: Chandler, Arizona
Posts: 2,850
iTrader: (0)
 
My '02 model already has the headlight setup like that. It doesn't come on until the engine starts. If the engine starts and dies, you need to turn the ignition off and back on again to reset it. This appears to be an afterthought solution for problem that should not have existed in the first place.

I have never messed with the pickup coils, and don't plan to. I've noticed most people get very little improvement from this. I believe the problem lies with the weak starting system rather than anything wrong with the engine or carbs, though I don't know how this causes such a difference between cold starting and hot starting.

Whether cold or hot, I feel the engine turns over too slowly, probably not fast enough to get a good spark. Part of that problem may be in the starter itself. I took mine off, took it apart, and used a whole can of contact cleaner to clean it out. It was filthy. Tons of black dust. I did not replace the brushes, though I probably should have. That made a very noticeable improvement in how fast the engine turned over. Hooking up jumper cables from a car battery also makes a noticeable difference.

So with a clean starter and a car battery, it seems to fire right up, which would seem to confirm my original feeling about the starting system. I think it needs a bigger battery and a stronger starter. New properly gapped plugs may help as well, though I got the expensive irridium plugs everyone recommends, and did not notice a difference.

One more thing I have noticed. If you use the choke (on mine anyway) even when warm, it seems to help starting. I don't know whether this indicates a carb problem or not. I have my pilot screws 3 turns out.

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 15 (permalink) Old 11-24-2011, 11:40 AM
Senior Member
 
kc2dgq's Avatar
 
Join Date: May 2010
Location: New Jersey
Posts: 3,350
iTrader: (13)
 
Garage
In your original message you mentioned backfiring. I am curious if you have messed with the idle mix screws. If you did, it is possible that you have them set improperly. A lot of people talk about setting them out to enrich the fuel mix (reducing popping in deceleration). I too have tried this, but the popping stopped only when I was out about 3 1/2 turns. After the bike cools down again it would be hard to start and it seemed to backfire which indicates to me too much fuel in the system.
My personal experience is that in setting the fuel mix too rich, and using the choke tends to flood the carbs and cause a backfire once it does ignite.

I would turn the screws back to about 2 turns out from bottom and see if that helps with starting cold.....assuming you did turn them out to begin with.

Just throwing out ideas...hope you get it solved!
kc2dgq is offline  
post #8 of 15 (permalink) Old 11-24-2011, 11:52 AM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,634
iTrader: (4)
     
Garage
95% of the time the cure is putting in a new AGM battery. If you have a regular wet cell that's not brand new.

Tip off is the backfires. This is fuel that was not igniting.

If after you clean off all your terminals and install a new AGM or one of the new lithium iron batteries , and still have a problem, you can try the pick up mod... But as I said 95% of the time the AGM does the trick.

I found that when hot, just giving it no choke but just a slight blip of throttle worked best as I hit the starter button.


Many vulcans are of course "old" now, so cleaning the contacts and brushes on the starter itself can help too...

Using the kill switch makes no sence as it only cuts power to the coils and let's all the lights stay on. Turning the key to off makes more sence as it resets everything. If your battery us so weak it won't start the bike with the headlight on that means you need a new battery........

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 #9 of 15 (permalink) Old 11-24-2011, 12:41 PM
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
A new AGM battery sorted my hot-starting problem out in an instant.

She starts right-up when warm with no choke and a little flick of the throttle.

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 #10 of 15 (permalink) Old 11-24-2011, 03:52 PM Thread Starter
Member
 
92' Vulcan Rider's Avatar
 
Join Date: Nov 2011
Location: Santa Barbara CA
Posts: 30
iTrader: (0)
 
Thanks everyone. I'll start with iridium plugs and an AGM battery. Is there more than one type of AGM battery? Should I be looking for a specific one? Amps/cca?
What the heck does AGM stand for? What should my spark plug gap be set at?:
Thanks again. Happy Turkey Day

Last edited by 92' Vulcan Rider; 11-24-2011 at 09:18 PM.
92' Vulcan Rider 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