Straight pipe or goats belly removal - 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!

 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 18 (permalink) Old 07-05-2017, 01:46 PM Thread Starter
Dirt to road
 
duraholiday's Avatar
 
Join Date: Apr 2015
Location: Michigan
Posts: 231
iTrader: (0)
 
Straight pipe or goats belly removal

I have the engine pulled out currently so im debating if I want to put straight pipes on or just take off the belly. So what do people recommend? Does it even sound good with straight pipes? And what are the sizes ill need for the carb?

From what ive read there are mixed reviews...

Sent from my SM-G900P using Tapatalk

Project Bike 92 VN750
Days running: 0
Project Pictures http://s1116.photobucket.com/user/dieinghost/library/

Up coming Projects:
NOW- Getting it running....
Winter of 2015- Bobber Build
duraholiday is offline  
Sponsored Links
Advertisement
 
post #2 of 18 (permalink) Old 07-05-2017, 05:38 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,679
iTrader: (4)
     
Garage
If you're just looking for loud.....removing the goats belly is what I'd do first.

Then....if that doesn't blow your ears out enough....don't do straight pipes, go with aftermarket slip-ons...preferably with removable baffles you can alter if you can still hear...
JimmyMac likes this.

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker is online now  
post #3 of 18 (permalink) Old 07-05-2017, 07:06 PM
Alpha Geek
 
Hexadecimus's Avatar
 
Join Date: Oct 2013
Location: Midwest USA
Posts: 487
iTrader: (1)
 
You'll want an H-pipe style exhaust crossover unless you want to lose some power and efficiency. Jet sizes will depend on what you end up doing with the intake/exhaust. This is a good place to start

Hexadecimus is offline  
 
post #4 of 18 (permalink) Old 07-05-2017, 08:35 PM
Member
 
Vulcanlover's Avatar
 
Join Date: Aug 2016
Posts: 86
iTrader: (0)
 
I don't agree

Quote:
Originally Posted by Hexadecimus View Post
You'll want an H-pipe style exhaust crossover unless you want to lose some power and efficiency. Jet sizes will depend on what you end up doing with the intake/exhaust. This is a good place to start
I don't agree with that, no offense meant. I took my goat's belly off and just put harley mufflers right on the stock pipes, made hangars for them in 5 minutes using flat bar that I painted black. They sound great, and with no doubt I didn't lose power, I noticed a gain in power. I did not re-jet the carbs, andmy bike sounds great. Of course to each his own but the biggest improvement I have made in my bike is removing the goat's belly.

1985 VN700A
FYI :
Kawasaki introduced the 750 cc class Vulcan worldwide in 1985. Due to tariff restrictions in the United States on bikes over 700 cc imported from Japan, the initial US spec model was limited to 699 cc. The tariff was lifted in 1986 and the Vulcan went to 749cc.
Vulcanlover is offline  
post #5 of 18 (permalink) Old 07-05-2017, 09:30 PM
Member
 
Vulcanlover's Avatar
 
Join Date: Aug 2016
Posts: 86
iTrader: (0)
 
Ebay

If you decide to go with Harley mufflers, I just looked and there are tons on Ebay as cheap as 30 bucks a pair with shipping. A lot of people that buy new Harleys put custom exhaust on right away and sell the stock mufflers cheap while they are just like new, thats how I got mine. If you go with straight pipes, please let us know how it works out, I am curious.
Attached Thumbnails
Click image for larger version

Name:	pipes1_opt.jpg
Views:	96
Size:	48.9 KB
ID:	38905   Click image for larger version

Name:	pipes 2_opt.jpg
Views:	102
Size:	52.6 KB
ID:	38913  

1985 VN700A
FYI :
Kawasaki introduced the 750 cc class Vulcan worldwide in 1985. Due to tariff restrictions in the United States on bikes over 700 cc imported from Japan, the initial US spec model was limited to 699 cc. The tariff was lifted in 1986 and the Vulcan went to 749cc.
Vulcanlover is offline  
post #6 of 18 (permalink) Old 07-06-2017, 09:21 AM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,679
iTrader: (4)
     
Garage
Quote:
Originally Posted by Vulcanlover View Post
I don't agree with that, no offense meant. I took my goat's belly off and just put harley mufflers right on the stock pipes, made hangars for them in 5 minutes using flat bar that I painted black. They sound great, and with no doubt I didn't lose power, I noticed a gain in power. I did not re-jet the carbs, andmy bike sounds great. Of course to each his own but the biggest improvement I have made in my bike is removing the goat's belly.
Where did you notice this "extra power"? You have Dyno figures or is this just "seat of the pants"?
Do you understand that removing weight off a bike can make it feel quicker?

Seriously, crossovers or the goats belly work to provide certain degrees of back pressure in the exhaust system. This really only effects the bike at lower RPM's, and likely isn't that noticeable until you stick the bike on a Dyno.
More open or freeer flowing exhaust can increase power at the top end. So it's really where you want to measure the power.
My project bike has no belly and fairly straight pipes. It feels "faster" but lost standing start races against my stock bike until it hit 5500 rpms. It then caught up....but basically was even at the end.
I'd rather have low end power than top end, but that's just me...

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker is online now  
post #7 of 18 (permalink) Old 07-06-2017, 10:16 AM
FREEBIRDS MC CENTRAL NY
 
OleDirtyDoc's Avatar
 
Join Date: May 2011
Location: Norwich,NY
Posts: 15,912
iTrader: (0)
     
Garage
Send a message via Yahoo to OleDirtyDoc
Quote:
Originally Posted by Knifemaker View Post
Where did you notice this "extra power"? You have Dyno figures or is this just "seat of the pants"?
Do you understand that removing weight off a bike can make it feel quicker?

Seriously, crossovers or the goats belly work to provide certain degrees of back pressure in the exhaust system. This really only effects the bike at lower RPM's, and likely isn't that noticeable until you stick the bike on a Dyno.
More open or freeer flowing exhaust can increase power at the top end. So it's really where you want to measure the power.
My project bike has no belly and fairly straight pipes. It feels "faster" but lost standing start races against my stock bike until it hit 5500 rpms. It then caught up....but basically was even at the end.
I'd rather have low end power than top end, but that's just me...
there is a lot to figure into a drag race.did you race both bikes before the belly removal?maybe was quicker to begin with. maybe one person was a better rider than the other? maybe one has better tires? maybe weight difference between the two riders?

Sent from my LGL34C using Tapatalk

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 #8 of 18 (permalink) Old 07-06-2017, 03:15 PM
Alpha Geek
 
Hexadecimus's Avatar
 
Join Date: Oct 2013
Location: Midwest USA
Posts: 487
iTrader: (1)
 
Quote:
Originally Posted by Vulcanlover View Post
I don't agree with that, no offense meant. I took my goat's belly off and just put harley mufflers right on the stock pipes, made hangars for them in 5 minutes using flat bar that I painted black. They sound great, and with no doubt I didn't lose power, I noticed a gain in power. I did not re-jet the carbs, andmy bike sounds great. Of course to each his own but the biggest improvement I have made in my bike is removing the goat's belly.
No offense taken, but it's an established fact of intake/exhaust engineering that shorter runners may gain you some flow rate and peak HP but you will lose more torque under the low and mid ranges for a net loss. Adding/removing a crossover has essentially the same effect through balancing the pulses and breaking up reversion waves, especially on a twin. That's why even Harley uses them from the factory. You have to view the entire power and torque graph as a 2-dimensional area. You'll have less total area under the graph with shorter runner or lack of crossover.

Unless you only care about drag racing above 6 or 7000 RPM, you'll lose torque, driveability, and efficiency below that. Even then, it's no guarantee that you'll actually be making more total output at the RPM you'll be running. You need a lot of dyno runs to know for sure. Like Doc said, too many factors.


Last edited by Hexadecimus; 07-06-2017 at 03:18 PM.
Hexadecimus is offline  
post #9 of 18 (permalink) Old 07-06-2017, 05:11 PM
Member
 
Vulcanlover's Avatar
 
Join Date: Aug 2016
Posts: 86
iTrader: (0)
 
Don't know

I don't question your math at all. I built hot rods for the street for years, and people told me I should run a crossover after my headers, and I never did. I can't argue because I have never tried it both ways, so I take your word for it. I do know that the goat's belly had to go either way because I just hated the 4-wheeler exhaust note. I didn't ride it much at all before I got rid of the GB and put on the new pipes so I really shouldn't have an opinion. Thanks for the info, and again, I do not question your math.

1985 VN700A
FYI :
Kawasaki introduced the 750 cc class Vulcan worldwide in 1985. Due to tariff restrictions in the United States on bikes over 700 cc imported from Japan, the initial US spec model was limited to 699 cc. The tariff was lifted in 1986 and the Vulcan went to 749cc.
Vulcanlover is offline  
post #10 of 18 (permalink) Old 07-16-2017, 01:03 AM Thread Starter
Dirt to road
 
duraholiday's Avatar
 
Join Date: Apr 2015
Location: Michigan
Posts: 231
iTrader: (0)
 
I decided to get these slip ons and weld together a cross "x" pipe.

I am pretty sure ill need to rejet it because i removed the ears and put pod filters on also.

Thanks for your inputs guys

Sent from my SM-G900P using Tapatalk

Project Bike 92 VN750
Days running: 0
Project Pictures http://s1116.photobucket.com/user/dieinghost/library/

Up coming Projects:
NOW- Getting it running....
Winter of 2015- Bobber Build
duraholiday 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













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