BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
Jwood & co JRC Engineering dealers Jwood & co
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Go2fer
Go2fer
Netherlands
Posts: 55
Joined: June 2011
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
33 registered members (AML), 248 guests, and 474 spiders.
Key: Admin, Global Mod, Mod
Newest Members
DT 150, DamienE, vietnammotorbike, Lennart Liljedah, Mal Wood
10290 Registered Users
Top Posters(30 Days)
Stuart 94
Lannis 65
Mori55 64
Popular Topics(Views)
636,740 mail-order LSR
Forum Statistics
Forums34
Topics67,373
Posts654,151
Members10,290
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
Bonneville intake balance tube...why? #125314
10/02/07 1:45 am
10/02/07 1:45 am
Joined: Apr 2006
Posts: 1,708
Virginia, USA
SBoyd Offline OP
BritBike Forum member
SBoyd  Offline OP
BritBike Forum member
Joined: Apr 2006
Posts: 1,708
Virginia, USA
I believe that the balance tube is there to help provide a smooth idle,...but how does it do that?

I happen to be replacing the Bing C/V's on my 1982 T140 with MK1 Amals. Now, since I'm completely redoing the intake manifolds, I have the option of providing the balance tube or not. No problem to do it, but what does it do and how does it do it? On the surface, it seems to be just an air leak to the other side that isn't doing anything at the time. And, of course singles don't need one and we have two singles here.
Racing engines don't use it. (this is not a race bike)


Stop the insanity.
Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: Bonneville intake balance tube...why? #125315
10/02/07 2:10 am
10/02/07 2:10 am
Joined: Nov 2004
Posts: 1,694
georgia
T
trumpetloon Offline
BritBike Forum member
trumpetloon  Offline
BritBike Forum member
T
Joined: Nov 2004
Posts: 1,694
georgia
OK... showing either my total ignorance; or deductive brilliance... here goes. My understanding is that the balance tube "equalises" the vacuum impulse of the two cylinders to improve cylinder filling and balance. I may have my head up my arse... but I believe this to be a tuning aid for low to moderate throttle settings enabling better side to side fuel distribution.

Racers don't generally care about smooth idle, EPA regulations or smooth transition from off throttle to part throttle. Their main focus is on the pilot/ main jet transition as revs generally will exceed the idle/low circuit on the track. Eliminating the balance tube allows each cylinder to be optimized seperately for mid to large throttle response.

Am I close, or a dunce???? confused


1974 TR5T
Re: Bonneville intake balance tube...why? #125316
10/02/07 11:34 pm
10/02/07 11:34 pm
Joined: Sep 2006
Posts: 398
hamilton on. can.
H
highway Offline
BritBike Forum member
highway  Offline
BritBike Forum member
H
Joined: Sep 2006
Posts: 398
hamilton on. can.
If you pinch the balance hose shut, when the engine is idleing, the engine stops. It is because the manifold on intake stroke is also drawing air/fuel from the other carb idle circuit. It is also why it is best to re-adjust the idle mixture screws a couple of times when setting idle. To get it to idle with the hose pinched you must turn up the idle screws.
By the time the needle and needle jet come into play the balance pipe has no effect.
By blanking the hose, one can sometimes get a worn out set of carbs idle lower.
Rick

Re: Bonneville intake balance tube...why? #125317
10/02/07 11:49 pm
10/02/07 11:49 pm
Joined: Mar 2006
Posts: 1,011
43.34 (4320') | -79.81 (-794...
Gunk Offline
BritBike Forum member
Gunk  Offline
BritBike Forum member
Joined: Mar 2006
Posts: 1,011
43.34 (4320') | -79.81 (-794...
Balance pipe blanking here we come.
cha-ching!

Thanks Rick.


"he who laughs fast, laughs first"~Gunk

Moderated by  John Healy 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.1.1