How a choke in a carburettor works....explanation! : Suzuki GSX-R Motorcycle Forums: Gixxer.com
» Insurance
» Suzuki GSX-R Prices
» Sponsors
Go Back   Suzuki GSX-R Motorcycle Forums Gixxer.com > Gixxer Forums > SRADs (97-00 600 and 96-99 750)

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-12-2012, 04:08 AM   #1
Armi
Lifetime Premium
 
Armi's Avatar
 
Join Date: Aug 2009
Location: london,uk
Motorcycle: gsxr 750 srad with a few mods thanks to the members on this site.See signature.
Posts: 9,474
How a choke in a carburettor works....explanation!

Actually i'm looking for one?

After that thread...cam't find it, I owed an explanation, as to how it works.

Have done some reading and am abit confused.

Read in one tuturiol that when it's cold, fuel sticks to the cylinder walls and therefore requires MORE fuel to start the bike....didn't say how it provides the extra fuel?!?!?!

In another tutorial, it says that the choke opens an air circuit and runs the engine at a higher rpm, which is totally contradictary to what was said above?

Whats a throttle valve?....that's the slide, right?
__________________

K6 thou forks/"K Tec" Springs, Brembo 19x20 RCS m/c, R1 calipers, Hel ss lines, Renthal dual compound grips, DID x ring gold chain, Renthal -1+2 sprockets, Sudco full exhaust, BMC filter, Gilles rearsets, Factory Pro engine covers, Samco Hoses, Ohlins rear shock, GPR steering damper, Yoshi MJN Jet kit thanks to our resident carb Ninja CCMHUNT!
Armi is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-12-2012, 06:13 AM   #2
dj_smurph
Lifetime Premium
 
Join Date: Jun 2012
Location: london, UK
Motorcycle: 98 600 srad,97 aprilia chesterfield rs125
Posts: 2,038
Re: How a choke in a carburettor works....explanation!

Throttle valve is the butterfly. The slide metres the fuel. The choke I think moves a butterfly that changes the air pressure difference across the carb and enrichens the air/fuel mix. How it does it I don't know
dj_smurph is offline   Reply With Quote
Old 11-12-2012, 07:13 AM   #3
TheGeek
Stupid. Who's with me?
 
TheGeek's Avatar
 
Join Date: Feb 2006
Location: Indiana
Motorcycle: Anniversary Edition 600 & Million Edition 1000
Posts: 11,230
Re: How a choke in a carburettor works....explanation!

Throttle plate is below the jets. It doesn't change any pressures, only air velociy at the jet which is the venturi effect vacuum. The choke is above the jet. Closing it applies a direct vacuum at the jet increasing the fuel.

This is in the simplest terms. It can get much more complicated.
TheGeek is online now   Reply With Quote
Old 11-12-2012, 07:40 AM   #4
ccmhunt
Superbike Champ
 
ccmhunt's Avatar
 
Join Date: Jan 2009
Location: Lawton, Ok
Motorcycle: 96 GSXR750 (parts), ZX7/9RR F-USA AMA SBK, 96 ZX7RR STREET, 96 WSBK ECKL ZX7RR
Posts: 10,851
Re: How a choke in a carburettor works....explanation!

In your Mikuni CV'S this>> In another tutorial, it says that the choke opens an air circuit and runs the engine at a higher rpm,
Remember, I told you that the choke plunger opened an air passage from above the piston diaphragm to the upper venturi on the engine side of the butterfly . This was the direct effect.
Now, what is the indirect effect?
ccmhunt is online now   Reply With Quote
Old 11-12-2012, 08:33 AM   #5
dj_smurph
Lifetime Premium
 
Join Date: Jun 2012
Location: london, UK
Motorcycle: 98 600 srad,97 aprilia chesterfield rs125
Posts: 2,038
Re: How a choke in a carburettor works....explanation!

The idirect effect is it lifts the slide more increasing the amount of fuel while keeping the amount of air the same enrichening the mix
dj_smurph is offline   Reply With Quote
Old 11-12-2012, 08:37 AM   #6
THE SRADIATOR
!##NULL##!
 
THE SRADIATOR's Avatar
 
Join Date: Nov 2001
Location: Works & Plays Well with Others (Sometimes)
Motorcycle: THE SRADIATOR
Posts: 23,122
Re: How a choke in a carburettor works....explanation!

I know this one...Less air ='s More fuel?
THE SRADIATOR is offline   Reply With Quote
Old 11-12-2012, 08:40 AM   #7
THE SRADIATOR
!##NULL##!
 
THE SRADIATOR's Avatar
 
Join Date: Nov 2001
Location: Works & Plays Well with Others (Sometimes)
Motorcycle: THE SRADIATOR
Posts: 23,122
Re: How a choke in a carburettor works....explanation!

Quote:
Originally Posted by TheGeek View Post
Throttle plate is below the jets. It doesn't change any pressures, only air velociy at the jet which is the venturi effect vacuum. The choke is above the jet. Closing it applies a direct vacuum at the jet increasing the fuel.

This is in the simplest terms. It can get much more complicated.
Any time someone whips out the word "Venturi" you know it's going to get complicated!
Although...for some, the word "Floats" has complications and a life all their own!
THE SRADIATOR is offline   Reply With Quote
Old 11-12-2012, 08:46 AM   #8
Armi
Lifetime Premium
 
Armi's Avatar
 
Join Date: Aug 2009
Location: london,uk
Motorcycle: gsxr 750 srad with a few mods thanks to the members on this site.See signature.
Posts: 9,474
Re: How a choke in a carburettor works....explanation!

I know what the venturi is.
If the choke plunger opens an passage above the piston diaphram, this will in turn lift the needle, allowing more fuel in,no?
I mean the slide, slides up the needle, allowing more fuel.

Can someone put up a correct diagram of whats going on?
Armi is offline   Reply With Quote
Old 11-12-2012, 09:13 AM   #9
TheGeek
Stupid. Who's with me?
 
TheGeek's Avatar
 
Join Date: Feb 2006
Location: Indiana
Motorcycle: Anniversary Edition 600 & Million Edition 1000
Posts: 11,230
Re: How a choke in a carburettor works....explanation!

Then that's not a choke... it's an enrichment mechanism.
TheGeek is online now   Reply With Quote
Old 11-12-2012, 09:37 AM   #10
Moto_Joe
Serial Comma Rapist Admin
 
Moto_Joe's Avatar
 
Join Date: Apr 2002
Location: Macon Ga
Motorcycle: 2006 GSXR 600 Racebike
Posts: 117,150
The real confusion comes in that choke enrichener and fast idle are all incorrectly used as if they are interchangeable only because they are used to achieve the same desired effect.

There are tons of things that are like this too.

Backfire/after fire
Flooding/gas fouling
Etc.
Moto_Joe is offline   Reply With Quote
Old 11-12-2012, 10:26 AM   #11
Iloveurmommy
Back Marker
 
Iloveurmommy's Avatar
 
Join Date: Jul 2011
Posts: 123
This is probably one of the best guides IMO to understanding carbs. I know it helped me a great deal.


http://dl.dropbox.com/u/106752/Manua...etion_1975.pdf

Here is the thread I found it in:

http://www.thegsresources.com/_forum...ighlight=Great

Enjoy!!!




Sent from my iPhone using Motorcycle.com Free App
Iloveurmommy is offline   Reply With Quote
Old 11-12-2012, 12:16 PM   #12
TT750
Lifetime Premium
 
Join Date: Nov 2007
Location: halifax ns, canada
Motorcycle: 99 750 (sold), 98 tlr (in progress), 07 f650 dakar (daily driver)
Posts: 6,079
Re: How a choke in a carburettor works....explanation!

cold fuel doesnt atomize well..

wish this showed a air choke like on the srad. instead the choke valve actually opens a port to let more fuel where in our carbs the choke valves lets vacuum travel to the diaphram and lift the slide and needle to let more fuel.


when you look at srad carbs and many others you will see the choke valve on the top of them. basically the direct opposite position then the video. because you want vacuum to be directed to the top side of the diaphram. when you pull the choke you open the port in the top of the bore on the engine side of the butterfly to let vacuum up to the top of the diaphram lifting the slide and needle.
__________________
99 750 srad.... my other hot blooded woman
TT750 is offline   Reply With Quote
Old 11-12-2012, 12:22 PM   #13
TT750
Lifetime Premium
 
Join Date: Nov 2007
Location: halifax ns, canada
Motorcycle: 99 750 (sold), 98 tlr (in progress), 07 f650 dakar (daily driver)
Posts: 6,079
Re: How a choke in a carburettor works....explanation!

in this video you can see the fuel being atomized into tiny droplets as it comes out the main jet kinda cool
TT750 is offline   Reply With Quote
Old 11-12-2012, 12:58 PM   #14
ccmhunt
Superbike Champ
 
ccmhunt's Avatar
 
Join Date: Jan 2009
Location: Lawton, Ok
Motorcycle: 96 GSXR750 (parts), ZX7/9RR F-USA AMA SBK, 96 ZX7RR STREET, 96 WSBK ECKL ZX7RR
Posts: 10,851
Re: How a choke in a carburettor works....explanation!

So after all the hints, we have a conclusion, the choke is an air mechanism, whose secondary function is to raise rpm and meter more fuel.
That's the distinction I was driving for, because all too often there is a misconception that there is a choke jet, or that the choke itself is metering fuel. So my questions in the other thread, that asked you all the ponder it, and gave you all the information that the mechanism opened the passage from venturi to chamber above diaphragm, was merely an exercise to make you arrive at a forgone conclusion and to remove the misconception of a choke fuel jet mechanism in our carbs.
__________________
[QUOTE=senator8]Haha! You're more than 1%. My bike ran perfectly all year. All I did was oil changes and thumbed the starter. While my competitors had bikes and carbs in pieces at the track I was enjoying a coffee and saying "thanks Chris"
ccmhunt is online now   Reply With Quote
Old 11-12-2012, 01:17 PM   #15
Apok
ICBA
 
Join Date: Aug 2011
Location: Newhall, CA
Motorcycle: '03 GSXR1000, '88 GSX 1100F, '92 GSX 1100F
Posts: 1,961
Re: How a choke in a carburettor works....explanation!

You bastage, both of my answers pertained to that.
Apok is offline   Reply With Quote
Old 11-12-2012, 01:20 PM   #16
THE SRADIATOR
!##NULL##!
 
THE SRADIATOR's Avatar
 
Join Date: Nov 2001
Location: Works & Plays Well with Others (Sometimes)
Motorcycle: THE SRADIATOR
Posts: 23,122
Re: How a choke in a carburettor works....explanation!

When he whips out the word "Venturi" from his vocabulary tool box, things are gonna get serious right quick round here! (I hate when things get serious as it goes against everything I stand for!)
THE SRADIATOR is offline   Reply With Quote
Old 11-12-2012, 01:22 PM   #17
THE SRADIATOR
!##NULL##!
 
THE SRADIATOR's Avatar
 
Join Date: Nov 2001
Location: Works & Plays Well with Others (Sometimes)
Motorcycle: THE SRADIATOR
Posts: 23,122
Re: How a choke in a carburettor works....explanation!

Quote:
Originally Posted by TT750 View Post
cold fuel doesnt atomize well..

wish this showed a air choke like on the srad. instead the choke valve actually opens a port to let more fuel where in our carbs the choke valves lets vacuum travel to the diaphram and lift the slide and needle to let more fuel.

http://www.youtube.com/watch?v=wyspAHrMbb8

when you look at srad carbs and many others you will see the choke valve on the top of them. basically the direct opposite position then the video. because you want vacuum to be directed to the top side of the diaphram. when you pull the choke you open the port in the top of the bore on the engine side of the butterfly to let vacuum up to the top of the diaphram lifting the slide and needle.

Ohhhhhhh...pretty colors!
See pretty...
THE SRADIATOR is offline   Reply With Quote
Old 11-12-2012, 01:30 PM   #18
dj_smurph
Lifetime Premium
 
Join Date: Jun 2012
Location: london, UK
Motorcycle: 98 600 srad,97 aprilia chesterfield rs125
Posts: 2,038
Re: How a choke in a carburettor works....explanation!

https://www.youtube.com/watch?v=APq5...e_gdata_player

This shows mjn kit working as well as fuel atomising
dj_smurph is offline   Reply With Quote
Old 11-12-2012, 07:23 PM   #19
TwistedMister
Lifetime Premium

 
TwistedMister's Avatar
 
Join Date: May 2003
Posts: 2,725
Re: How a choke in a carburettor works....explanation!

Quote:
Originally Posted by Armi View Post
In another tutorial, it says that the choke opens an air circuit and runs the engine at a higher rpm, which is totally contradictory to what was said above?

he said, it adds more air, he also said that in another thread a while back when I was going through my carbs when I thought fuel may be leaking out the choke o-rings..

he said "remember the choke adds more air"

I fear you blonds aren't going to do so well on the test...
TwistedMister is offline   Reply With Quote
Old 11-12-2012, 07:26 PM   #20
TwistedMister
Lifetime Premium

 
TwistedMister's Avatar
 
Join Date: May 2003
Posts: 2,725
Re: How a choke in a carburettor works....explanation!

Quote:
Originally Posted by dj_smurph View Post
https://www.youtube.com/watch?v=APq5...e_gdata_player

This shows mjn kit working as well as fuel atomizing
is that the perforated needle set up?

like to get me a good set of spares and try those some day, prolly when I hit the lotto..
TwistedMister is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump

Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 04:13 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2008 2013 Gixxer.com
Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Forum Honda 600RR Kawasaki Forum Yamaha R6 Forum Yamaha FZ-09 Forum
1199 Panigale Forum Roadglide Forum Honda CBR1000 Forum Vulcan Forum Yamaha R1 Forum Yamaha R3 Forum
Ducati Monster Forum Harley Forums Honda CBR250R Forum ZX10R Forum Star Raider Forum Yamaha Viking Forum
Suzuki GSXR Forum V-Rod Forums Honda Shadow Forum Kawasaki Motorcycle Forum Star Warrior Forum KTM Duke 390 Forum
SV650 Forum BMW S1000RR Forum Honda Fury Forum Kawasaki Versys Forum Drag Racing Forum Ducati 899 Panigale Forum
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes BMW NineT Forum
Volusia Forum BMW F800 Forum Triumph 675 Forum MV Agusta Forum HD Street Forum Suzuki GW250 Forum
Yamaha Motorcycles Victory Gunner Forum Honda Vultus Forum HD LiveWire Forum Ninja H2 Forum Ducati Scrambler Forum