Could use some input regarding a running issue... - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
VN750 General Discussion

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 06-27-2010, 11:51 AM Thread Starter
Member
 
kontiki's Avatar
 
Join Date: May 2009
Location: Columbia, SC
Posts: 91
iTrader: (0)
 
Could use some input regarding a running issue...

I wonder if any of you experts might comment on this issue that just popped up on my 1996 VN750 (8.5K miles) I've been driving it fairly regularly for a year now with no issues; bought it from an older gentlemen who didn't rid it much.

On the way home from work Friday evening I noticed the engine running rough (actually sounded like a cylinder missing) as I was heading down a short stretch of road to my house. Its downhill and requires little to no throttle. As I pulled in the driveway and stopped at the garage the engine was idling low and rough and stalled. I shut it down and finally got a chance to check it out this morning.

It cranked up Okay but I noticed the same rough running at idle but seemingly smooth and normal at RPM above about 2K. I pulled each plug wire off in turn to try and isolate the cylinder. I could hear that all four plugs were firing but noticed little or no change roughness when I pulled the rear plugs, so it appears the rear cylinder is at issue.

I then pulled the seat off and checked battery voltage just to eliminate that: 12.2 V ignition off, 14.3 or so volts when I rev to 4K so that appears to be fine. Then pulled the tank checked fuel flow while sucking on a piece of tubing connected to the vacuum fuel valve - fuel flow was excellent from both sides.

At this point I'm thinking some bad fuel or some dirt in the rear carb that has messed up the idle jet. I am planning on pulling the carbs and and cleaning them up then installing all new fuel and vacuum lines to the carbs. Any Ideas or suggestions?

Thanks in advance for any input,

Scott

1996 Vulcan 750
1980 XJ650 Maxim
kontiki is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 06-27-2010, 11:55 AM
Old Truck Junkie
 
niterider's Avatar
 
Join Date: Jul 2007
Location: Roby Texas
Posts: 4,130
iTrader: (15)
 
Drain the fuel out of both carbs. Use some water removing treatment and go from there.

02 honda sabre 1100
niterider is offline  
post #3 of 12 (permalink) Old 06-27-2010, 12:29 PM
Members who have donated towards server costs
 
cm4cm5's Avatar
 
Join Date: Feb 2007
Location: owensboro ky
Posts: 355
iTrader: (3)
 
try running seafoam through it. to clean the jets and fuel system. might save a carb pull.





Jeff Brooks
Owensboro KY
'94 Vulcan 750

http://youtube.com/user/cm4cm5
cm4cm5 is offline  
 
post #4 of 12 (permalink) Old 06-27-2010, 12:47 PM
Calif Rider
 
weh44att's Avatar
 
Join Date: Jan 2006
Location: Petaluma Calif
Posts: 725
iTrader: (0)
 
You said you heard that all the plugs were firing. Did you visually check that you have a spark at each plug in the rear. A wire could have come loose at the rear coil. This happened to me just a few weeks ago,and my bike ran like yours in now because of the loose wire.

2004 25,500 miles
Led tail light enhancement
Homemade floor boards
Headlight modulator
Extra heat sink on R+R
R+R relocation
Homemade driver's backrest
Fused Stator
Mcct conversion-cost 4.50
Ride-on in tires
crash bar with home made hyway pegs
iridium plugs
home made fork wind deflectors
coil pickups adjusted.
Kenda kruz tires 110/90 170/80
weh44att is offline  
post #5 of 12 (permalink) Old 06-27-2010, 03:35 PM Thread Starter
Member
 
kontiki's Avatar
 
Join Date: May 2009
Location: Columbia, SC
Posts: 91
iTrader: (0)
 
Thanks for the replies fellas. I could hear the "clicking" of the spark jumping as I disconnected the wires and held the plug wire near the plug tip. I could hear it on all four. Plus, I'm thinking that if it was the wires it would run ragged at all RPMs not just idle.

I use sea foam periodically... but I did get caught in a Major rain storm a week ago. Its possible some water got into the tank somehow. In looking at the bottom of the carbs I see what looks like an allen screw and a nipple out the bottom. Is that how they are drained? I tried loosening that screw its in there tight... sure would hate to strip the thing.

1996 Vulcan 750
1980 XJ650 Maxim
kontiki is offline  
post #6 of 12 (permalink) Old 06-27-2010, 03:46 PM
Old Truck Junkie
 
niterider's Avatar
 
Join Date: Jul 2007
Location: Roby Texas
Posts: 4,130
iTrader: (15)
 
Don't strip it. Just go with the water treatment. I use some called "heet." There are others. Run the engine after putting some in the tank, also when running at high rpms 5k or so, turn the petcock lever to reserve and run it for a few miles. Don't forget to turn it back to on.

02 honda sabre 1100
niterider is offline  
post #7 of 12 (permalink) Old 06-27-2010, 04:16 PM Thread Starter
Member
 
kontiki's Avatar
 
Join Date: May 2009
Location: Columbia, SC
Posts: 91
iTrader: (0)
 
I just drained the tank... by removing the petcock. About a tablespoon of water was in it. I then poured in a couple cusps of fresh gas and some sea foam and sloshed it around and drained that. If there was some water in the tank it certainly could have gotten into the crabs so I want to drain them.

Before I put it all back I want to replace the gas lines and vacuum line, they look old.. probably the original equipment. Where is a good source of new gas & vacuum line?

1996 Vulcan 750
1980 XJ650 Maxim
kontiki is offline  
post #8 of 12 (permalink) Old 06-27-2010, 04:20 PM
Old Truck Junkie
 
niterider's Avatar
 
Join Date: Jul 2007
Location: Roby Texas
Posts: 4,130
iTrader: (15)
 
An auto supply store should do. Take the old hoses with you for sizing.
Go ahead and use a bit of water remover. You can use sea foam, but water remover is a lot cheaper. That is up to you.

02 honda sabre 1100
niterider is offline  
post #9 of 12 (permalink) Old 06-27-2010, 04:50 PM Thread Starter
Member
 
kontiki's Avatar
 
Join Date: May 2009
Location: Columbia, SC
Posts: 91
iTrader: (0)
 
Thanks fellas. I drained the carb bowls also. Now for some new fuel and vac line and fingers crossed.

1996 Vulcan 750
1980 XJ650 Maxim
kontiki is offline  
post #10 of 12 (permalink) Old 06-28-2010, 11:33 AM
new owner
 
Join Date: Apr 2010
Location: West Fargo ND
Posts: 79
iTrader: (1)
 
I'm in the same boat (was just going to post a thread for comments) We had some very heavy rain here, its been raining almost every day for a couple weeks so the bike has not got any use in about a week and half. Last monday we got 4 inchs in 3 hours.. its also been very HIGH humidity. And yes the bike is outside at all times (wish it wasnt, but it is). I took it for a ride last thursday and it was running "odd" i couldnt put my finger on it, but it was strange.It was just to a parts store a few blocks away so it was a short ride. Saturday I took it out and it was still odd, I thought maybe it was missing but under power it felt fine. It did surge/miss a couple times at a steady speed.

That worried me so i drove in town as i didnt want to die out on the road. it seemed to run fine at lower speeds but have that wierd 2 seconds of good, 1 second of bad hicup.

I felt it was moisture and drove it a bit and after 15-20 minutes it seems to be running fine now. So I'm going to assume it was moisture.

My question, is where? In the tank (it seems from this thread you guys think that may be it). I know i have had cars with moisteure in the Cap (distributer) that cuased this type of problem. But I'm assuming that wont be the case here.. (as this has elecetronic ignition (right?).

Guess i will get some fuel line stuff and put in tank for mositer and hope that was it..
clok1966 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