'89 Engine Bog 4th & 5th Gear - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Engine / Exhaust / Cooling
\ From the radiator, through the case and out
the exhaust. If it has to do with the cooling,
engine or exhaust, discuss it here!

 2Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 08-23-2016, 05:01 PM Thread Starter
Junior Member
 
Join Date: Aug 2016
Location: Virginia
Posts: 4
iTrader: (0)
 
'89 Engine Bog 4th & 5th Gear

Hey guys,

I got my first bike this year and its an '89. Needless to say with it being that old it has a few little quirks but no real issues until late. I found some threads related to this topic but their issues seemed to be slightly different.

When accelerating at a normal pace I experience no issues in 1st-3rd gear. However, at mid range in both 4th and 5th gear (while steadily accelerating) the engine bogs down quite hard (but will not cut out). This issue is explicitly limited to 4th and 5th. But if while in 4th or 5th I accelerate hard I experience no bog issues and the bike picks right up.

No work has really been done to the bike yet, I did change out the spark plugs today before riding though. Any help on this is much appreciated, thank you in advance!
LLamaMaster22 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 08-23-2016, 05:29 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,644
iTrader: (4)
     
Garage
Please introduce yourself in the "Newbie Check-In forum.


So you're saying it loses power if you try accelerating "slowly" from 3,000-4,000 rpms while in 4th or 5th....but takes off fine if you crack open the throttle a lot?

Bike idles fine and both cylinders are firing?

Sounds like you might have a torn or leaking diaphragm in your carb(s)

Check your air filters and intake hoses (maybe something crawled in there) pull out the vent hose going into the back of the right ear, cut the end at a 45degree angle and re~insert it.



It's odd that it doesn't do it in lower gears. What rpm do you normally shift at?
Thorn likes this.

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/

Last edited by Knifemaker; 08-23-2016 at 05:32 PM.
Knifemaker is offline  
post #3 of 11 (permalink) Old 08-23-2016, 05:42 PM
Senior Member
 
Join Date: Nov 2015
Location: Pittsburgh, PA
Posts: 1,075
iTrader: (0)
 
Garage
When in 1-3 are you giving it as much throttle as you give when you're in 4-5 and it starts to bog? Trying to determine if would start to bog at, say, 65% throttle regardless of what gear you're in, but you just don't open it up that much in low gears. I personally don't use a ton of throttle until I'm on the highway, so I wouldn't notice a mid-to-high throttle problem until I was past the low gears.
Just a thought.

1992 US-nonCA * tuxedo mod * r/r relocated

Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
Thorn is online now  
 
post #4 of 11 (permalink) Old 08-23-2016, 05:52 PM Thread Starter
Junior Member
 
Join Date: Aug 2016
Location: Virginia
Posts: 4
iTrader: (0)
 
Quote:
Originally Posted by Knifemaker View Post
Please introduce yourself in the "Newbie Check-In forum.


So you're saying it loses power if you try accelerating "slowly" from 3,000-4,000 rpms while in 4th or 5th....but takes off fine if you crack open the throttle a lot?

Bike idles fine and both cylinders are firing?

Sounds like you might have a torn or leaking diaphragm in your carb(s)

Check your air filters and intake hoses (maybe something crawled in there) pull out the vent hose going into the back of the right ear, cut the end at a 45degree angle and re~insert it.



It's odd that it doesn't do it in lower gears. What rpm do you normally shift at?
Yes, I wouldn't say "slowly" accelerating, I'm not pinning it, but yes if I do crack open the throttle 75% or more I experience no issues. Also I normally shift around the 5k mark. Thank you I will try to take a look at the carb!


Quote:
Originally Posted by Thorn View Post
When in 1-3 are you giving it as much throttle as you give when you're in 4-5 and it starts to bog? Trying to determine if would start to bog at, say, 65% throttle regardless of what gear you're in, but you just don't open it up that much in low gears. I personally don't use a ton of throttle until I'm on the highway, so I wouldn't notice a mid-to-high throttle problem until I was past the low gears.
Just a thought.
I intentionally tested this issue out by giving it the exact same amount of throttle through all 5 gears and the issue still only happened in 4th and 5th gear. Honestly I'm usually on the throttle pretty hard regardless, the only time this issue is truly an issue is while I'm trying to cruise down the highway as it starts bogging right at the perfect throttle position for highway riding.
LLamaMaster22 is offline  
post #5 of 11 (permalink) Old 08-23-2016, 07:01 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,644
iTrader: (4)
     
Garage
Sounds like a carb or fuel delivery issue...The only other thing I can think of is you have a leak in your vacuum line to the petcock...
I'd Seafoam the crap out of it after checking that the carbs are opening right...

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 #6 of 11 (permalink) Old 08-24-2016, 11:58 PM
I'm a rider
 
One1's Avatar
 
Join Date: May 2014
Location: Signal Mountain, TN
Posts: 765
iTrader: (0)
 
Garage
I think the issue is more obvious than we are making it out to be. That's how long it takes for your fuel bowl to run out of fuel. You're running lean. When you start out from idle your bowls are full, after a good run through 1st, 2nd, and into third you have sucked your bowls dry. At least one of your carbs is lean. I'd check your floats and see if one is set to not allow as much fuel in as you need.
OleDirtyDoc likes this.


1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

Engineering solutions for the VN750 Community.
One1 is offline  
post #7 of 11 (permalink) Old 08-25-2016, 08:20 AM
Senior Member
 
Join Date: Nov 2015
Location: Pittsburgh, PA
Posts: 1,075
iTrader: (0)
 
Garage
Quote:
Originally Posted by One1 View Post
I think the issue is more obvious than we are making it out to be. That's how long it takes for your fuel bowl to run out of fuel. You're running lean. When you start out from idle your bowls are full, after a good run through 1st, 2nd, and into third you have sucked your bowls dry. At least one of your carbs is lean. I'd check your floats and see if one is set to not allow as much fuel in as you need.
An empty bowl wouldn't give him power back at full throttle in 4th & 5th though.

1992 US-nonCA * tuxedo mod * r/r relocated

Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
Thorn is online now  
post #8 of 11 (permalink) Old 08-25-2016, 08:27 AM
FREEBIRDS MC CENTRAL NY
 
OleDirtyDoc's Avatar
 
Join Date: May 2011
Location: Norwich,NY
Posts: 15,888
iTrader: (0)
     
Garage
Send a message via Yahoo to OleDirtyDoc
Question of the day,is the bike stock,earshaved,stock exhaust, degoated?

ONE RATS ASS GIVEN PER POST
Support your local FREEBIRDS MC
1986/5 Vn700/750 Frankenfook cross eyed bitch "Mellisa Fayhe"
I am a BIKER and i'm proud.FREEBIRDS MC CENTRAL NY

lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
OleDirtyDoc is offline  
post #9 of 11 (permalink) Old 08-25-2016, 08:35 AM
Senior Member
 
Join Date: Nov 2015
Location: Pittsburgh, PA
Posts: 1,075
iTrader: (0)
 
Garage
Quote:
Originally Posted by OleDirtyDoc View Post
Question of the day,is the bike stock,earshaved,stock exhaust, degoated?
You all heard the man. No more questions today. We've hit our quota.

1992 US-nonCA * tuxedo mod * r/r relocated

Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
Thorn is online now  
post #10 of 11 (permalink) Old 08-25-2016, 09:34 PM Thread Starter
Junior Member
 
Join Date: Aug 2016
Location: Virginia
Posts: 4
iTrader: (0)
 
The bike is completely stock with the exception of removed baffles. Also nothing was changed or adjusted prior to this issue beginning.
LLamaMaster22 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