Should I up the size of my jets? - 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 10 (permalink) Old 06-30-2010, 09:31 AM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
Question Should I up the size of my jets?

I purchased a '93 a couple of weeks ago and it ran good when I test drove it. Liked it. Bought it. As soon as I got it home it was running rough and sputtering around 3k - 4k rpm. Read lots of threads on here = I added SEAFOAM because...well that was the answer (no matter what the quesion was...well almost anyway.)

After SEAFOAM. Bike started smoking but running better. Mostly smoking from the front cylinder exhaust...and I mean at times A LOT of white/grey smoke. Inside exhaust from front was wet; inside the exhaust from the rear was nice and dry. Smoke/Exhaust does not smell sweet like coolant but more like fuel. Idled okay at first but then I drove it and more sputtering and popping....then it wouldn't idle. Would only start with throttle opened about half way. I've read about this kind of problem on here and figured the SEAFOAM loosened something up and carbs needed a good cleaning. (IN PROCESS NOW = carbs are off the bike, tank drained in case of bad gas, petcock removed for cleaning)

Skip to here for the real question...
My question, for now, is that since the carbs are off the bike, should I change from the stock jets that are in there to larger size? The bike has the stock air box w/ears setup but it has Cobra pipes.

There will be more to come as I put the newly cleaned carbs back on the bike...
CDUB is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 06-30-2010, 10:44 AM
On His Lady Vulcan
 
wkrizan's Avatar
 
Join Date: Apr 2008
Location: Washington State
Posts: 1,647
iTrader: (10)
 
On these bikes you do not need to rejet for after market pipes, rejet only if you change the air intake. Just make sure your pilot screws are turned out 2.5 - 2.75 out. It sounds to me like your front float got stuck is all, so a really good cleaning aught to do you wonders. Good luck.

"You came out of your mom looking like SHlT. She thought you were beautiful. Don't know what scared me most, your looks or her judgment."











Pictures of the "Ladies"
wkrizan is offline  
post #3 of 10 (permalink) Old 06-30-2010, 11:14 AM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
Ok, thanks for the advice on jetting. I'll stick with the stock jets.
BTW, the pilot screws were at 4 turns out prior to the cleaning. I was planning on trying 2.5, so thanks for the tip on that too!
CDUB is offline  
 
post #4 of 10 (permalink) Old 06-30-2010, 01:11 PM
Senior Member
 
dirtrack650's Avatar
 
Join Date: Jul 2007
Location: Castle Rock, Wa
Posts: 1,750
iTrader: (0)
 
Quote:
Originally Posted by CDUB View Post
Skip to here for the real question...
My question, for now, is that since the carbs are off the bike, should I change from the stock jets that are in there to larger size? The bike has the stock air box w/ears setup but it has Cobra pipes.
Here's a suggestion: The tuning of the carbs can be easily determined by inspecting the spark plugs. They should be a light tan color if your jets correct.

I had Cobra's on for a few years (until I got tired of the noise - switched to HD Sportster XL mufflers) and should have changed the jetting but was too lazy to pull the carbs. The result was a loss of midrange and high end power and purple exhaust headers due to heat. I did get some great mpg running that lean! If you want maximum value from your Cobra's I'd go up one jet size on both the idle and mains - if your plugs tell you too...

BTW - If you are going to leave the ears on, invest in better air filters. Plan ahead - if you go with free flowing air filters, you will need to increase the jet size even more. Cobra's and K&N's really open up the power band on our little twins.

Have fun,

DT

95 VN750 (eBay)31k+
GL1100 front fender
OEM engine guard
OEM high back rest
'V-Twin' HWY pegs
Black 750 Spectre handlebars
SunPro Volt Meter (Amazon)
Maier bug shield (JCW)
Bar Ends anti-vibe (JCW)
Emgo air filters
Tank bag-Eclipse
Tail bag-FroZone Cooler
Back Rest-Igloo 6 pak cooler
WalMart Saddle Bags
R/R Relocate
Dry Splines Lubed
AGM DieHard-Sears
Gutted Goat
Sporster XL Mufflers
LED's-stop,tail,turn,marker
Pickup coil mod to .45mm
Silverstar headlight
Rotella T6
dirtrack650 is offline  
post #5 of 10 (permalink) Old 07-01-2010, 11:03 AM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
The spark plugs from the rear cyl were more black than tan. The fronts were black and wet. I've cleaned them and will check them again after I put the carbs back on.

Any suggestions were I can get jets without buying a $$$ jet kit?

Also suggestions (including part no.) for better air filters (cheaper than K&N)?

Thanks again for the helpful suggestions!!
CDUB is offline  
post #6 of 10 (permalink) Old 07-01-2010, 11:55 AM
On His Lady Vulcan
 
wkrizan's Avatar
 
Join Date: Apr 2008
Location: Washington State
Posts: 1,647
iTrader: (10)
 
Again, you DO NOT need to rejet for after market pipes on these bikes. If you still desire to go that route then so be it, you can get them at any local Kawasaki dealer for 6-7 bucks each, or google "motorcycle jets" and you can find them for cheaper but you'll pay shipping which will be more expensive in the end.

"You came out of your mom looking like SHlT. She thought you were beautiful. Don't know what scared me most, your looks or her judgment."











Pictures of the "Ladies"
wkrizan is offline  
post #7 of 10 (permalink) Old 07-01-2010, 08:46 PM
Sparky!!!
 
slimvulcanrider's Avatar
 
Join Date: May 2008
Posts: 8,695
iTrader: (3)
   
Garage
shoot lance a PM on jets, he beats price on most online offer you can find.....
slimvulcanrider is offline  
post #8 of 10 (permalink) Old 07-01-2010, 09:57 PM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
Thought I would share this picture of the petcock since there are some questions about the missing filter for the reserve. Yes, when I pulled mine the reserve was just an empty hole, but I heard something loose inside the tank. I found it to be the missing reserve filter. I was able to retrieve it with a piece of rubber hose and chewing gum on the end. Yes, I actually thought that might work...and so it did. On the FIRST try!!! Here's the pic after I put it back in the petcock.

CDUB is offline  
post #9 of 10 (permalink) Old 07-01-2010, 10:01 PM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
At this point, I've decided to stick with the stock air filters and leave the stock jets alone. I got the carbs back in tonight (with quite a bit of sweat and twisting and pushing, I might add). I was about to install the gas tank and try to figure out where all of those vacuum lines went... when it started raining.


more to come....
CDUB is offline  
post #10 of 10 (permalink) Old 07-01-2010, 10:07 PM Thread Starter
'93 VN 750
 
CDUB's Avatar
 
Join Date: Jun 2010
Location: Gainesville, Florida
Posts: 23
iTrader: (0)
 
Also, I wanted to say thank you to dirtrack650, wkrizan and slimvulcanrider for the suggestions about the jets, etc... I'll definitely look into those options when I decide to change the jets and go with better air filters. For now, I want to see how it runs with the stock ones after all of the cleaning.
CDUB is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Tags
carbs , cobra , cobras , jetting

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