jumped timing? vacuum gauge very erratic, low power, top speed 70mph. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
New Member Introductions First Post?
Make your big introduction here.

 
LinkBack Thread Tools Display Modes
post #1 of 3 (permalink) Old 08-21-2012, 12:57 AM Thread Starter
Junior Member
 
Join Date: Aug 2012
Posts: 4
iTrader: (0)
 
jumped timing? vacuum gauge very erratic, low power, top speed 70mph.

New to this site. been riding for 45 years, making repairs for almost the same time. I recently purchased a 1989 vn-750a, with 25k miles no leaks no smoke, starts with no choke, has a strange sound like a mild blow by from valve over-lap. I placed vacuum gauges on the carbs for synchronizing but the needles are jumping too wildly be read. unable to do a compression check at the moment, throttle response is slow, take off in first gear is agonizingly slow. (my last bike was a hayabusa). I have my suspicions as to what is wrong but thought maybe someone might have a good place to start to identify the problem. plugs are new, when the vacuum line on the left is removed from the carb, the bike dies immediately . when the vacuum line is removed from the right carb there is no effect. open to any and all suggestions for a cure. thanks
flyinlowjoe is offline  
Sponsored Links
Advertisement
 
post #2 of 3 (permalink) Old 08-21-2012, 01:41 AM
1986 VN750
 
thtanner's Avatar
 
Join Date: Nov 2011
Location: Dana Point, CA
Posts: 3,255
iTrader: (8)
 
Garage
When you are checking the vacuum and syncing the carbs, you need to restrict the flow from both carbs via little flow valves. They should have been included in the kit.

Vacuum should not be left open, or it will cause issues (such as the bike dying). Left vacuum goes to the petcock, as I am sure you found out, and the right goes to the emissions system. There is a procedure called coastering/marbling that gets rid of it (the right gets plugged)

Now, the noise you hear, is it a tapping sound, upper cyl? If so, probably the Automatic Cam Chain Tensioners. They begin to get weak, and can cause the cam chain to jump, affecting timing. If they're failing, switch to manual tensioners instead of replacing them.

Your issue may just be due to dirty carbs, with the other noises of the bike possibly leading you down other paths. Run a heavy dose of seafoam in your gas for a few tanks and see where you land?

Both of my bikes start without choke fairly fine, as long as its warmish out. If it's colder, it's just easier to hit the choke.

Welcome, and best of luck!

PDF Manual: http://www.tocmanufacturing.com/File...nd%20Parts.pdf

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

Last edited by thtanner; 08-21-2012 at 02:03 PM. Reason: Spelling
thtanner is offline  
post #3 of 3 (permalink) Old 08-21-2012, 12:59 PM
Registered User
 
Join Date: Aug 2011
Location: GreenwoodFrickinLakeNY
Posts: 10,354
iTrader: (8)
   
...an 89 with 25k ?...yup...the ACCT....



Wolfie 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