Poor performance - 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 9 (permalink) Old 07-19-2007, 10:51 PM Thread Starter
Junior Member
 
Join Date: Mar 2007
Location: Lexington, KY
Posts: 27
iTrader: (0)
 
Poor performance

Hey guys, I've done a lot of reading but I can't find anaything about this symptom.

I left my stock '99 bike parked in a lot under a cover for a month. The bike is in Kentucky where it's hot and humid. The bike was left with 1/4 tank. The problem started on the first ride. It started with a normal warm-up but the needle had an occasional tick where it would jump 500 rpm's. After warm-up and the choke closed I went to give it some throttle. When I did this the engine reved up to 4000 and then would struggle to get any higher and would start bouncing up and down between 4-6 grand.

I checked the plugs and they were all normal except the rear right, which was black. I added 4 oz of seafoam to the 1/4 tank and expected a change. It sounds a little low and it is definately running rough. It stalls with a quick pull in the throttle but after moving the throttle will wind the revs all the way up without any trouble.

It used to get ~ 50mpg and since returning it is getting about 30 mpg. I replaced the plug with no change. Again, it idles starts and idles normal. I'm still waiting for the seafoam to work it's magic. There's no telling what the heat did over a month. Help! Thanks.

Last edited by wheeler; 07-19-2007 at 11:03 PM. Reason: bike
wheeler is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 07-19-2007, 11:00 PM
HAWK
 
Ccspinner's Avatar
 
Join Date: Feb 2006
Location: Chicago land
Posts: 2,576
iTrader: (9)
 
Send a message via Yahoo to Ccspinner
Do you have the Ears?
If so check the vent tube on teh right side to make sure it is not unplugged or bottomed out.

Chad Falstad "Hawk"
Vroc #17649
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
2001 VN 750 "Sold June with 2008 with 21,000""Serinity"
Ccspinner is offline  
post #3 of 9 (permalink) Old 07-20-2007, 03:30 AM
and the Adventure Cycle
 
hyperbuzzin's Avatar
 
Join Date: Jun 2004
Location: Western PA
Posts: 6,138
iTrader: (1)
   
Wouldn't hurt to give the air filters a quick check too. Make sure the filters are in good condition, clean (but oiled properly), and no critters in them.
And while you're at it, check that the wire from the black plug is connected good to the coil.


AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC


"When life throws you curves,
Aim for the apex."

Author Unknown
hyperbuzzin is offline  
 
post #4 of 9 (permalink) Old 07-20-2007, 10:51 PM Thread Starter
Junior Member
 
Join Date: Mar 2007
Location: Lexington, KY
Posts: 27
iTrader: (0)
 
Thanks for the suggestions. Everything seems to be as expected. I believe that all four plugs are firing; filters look good too. It's just running really rough and is sucking down gas.
wheeler is offline  
post #5 of 9 (permalink) Old 07-21-2007, 01:30 PM Thread Starter
Junior Member
 
Join Date: Mar 2007
Location: Lexington, KY
Posts: 27
iTrader: (0)
 
I forgot to note that the bike has the coasters removed and it also has a MF battery. Otherwise, is there anything specific that would cause the tach to jump around independent of the engine? Also, would an exhaust leak cause any engine problems like slow acceleration or louder that normal sound? Thanks!
wheeler is offline  
post #6 of 9 (permalink) Old 07-21-2007, 03:38 PM
Members who have donated towards server costs
 
Crobins365's Avatar
 
Join Date: Jul 2006
Location: Kennett Square, PA
Posts: 3,505
iTrader: (48)
     
Someone correct me, but if the right rear plug was black (oily?), it's running rich (which might explain the excess fuel consumption - although that's a whole lot of excess).

Just checking: the bike was coastered and you removed the coasters? So now air's moving through your reed valves? Are all the hoses set up through the emissions chamber to the right places (two large ones to the reed valve inlets; one to the airbox (although big) and a small one to the right vacuum port.

Finally, have you sync'd your carbs? It may be irrelevant here, but I do know that the tach will jump all over the place when the carbs are outta sync.

C
Crobins365 is offline  
post #7 of 9 (permalink) Old 07-26-2007, 08:44 PM
Junior Member
 
ricerat750's Avatar
 
Join Date: Jul 2007
Location: cape coral
Posts: 4
iTrader: (0)
 
Send a message via AIM to ricerat750
air/ mixture problems

I have just did an ear shave today- and now I have a big prob with my air mixture. I pinched the right vaccum hose to see if it would help at all, and to no improvement, I am started to get a little frustrated. The bike seems to idle very high, yet when I adjust the idle to run smooth, as soon as I start to get the bike going, it seems to revv high again. any suggestions for mynext step? Am I going to have to re-jet the carbs?
ricerat750 is offline  
post #8 of 9 (permalink) Old 07-26-2007, 09:22 PM
HAWK
 
Ccspinner's Avatar
 
Join Date: Feb 2006
Location: Chicago land
Posts: 2,576
iTrader: (9)
 
Send a message via Yahoo to Ccspinner
Sounds like you have a vacume leak, Check you boots on the carb.
They have a way they need to go or they will leak.

Chad Falstad "Hawk"
Vroc #17649
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
2001 VN 750 "Sold June with 2008 with 21,000""Serinity"
Ccspinner is offline  
post #9 of 9 (permalink) Old 07-26-2007, 09:56 PM Thread Starter
Junior Member
 
Join Date: Mar 2007
Location: Lexington, KY
Posts: 27
iTrader: (0)
 
I have confirmed an exhaust leak in the front cylinder. I hope that clears up some of my concerns. Otherwise, I'll assume you're refering to the black boots that connect to the carbs, Ccspinner? The big 2, or are there more? Thanks for the help.

'99 VN750
23K
wheeler 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