MicroSquirt.com read only forum (Jan.15,2018)

i am in need of a set of throttle bodies for a 250cc ninja. anyone have a clue as to where i would come up with around a 30-35mm throttle body apart from "make it your self"?

Will's Fiero wrote:

Marcus wrote:Make/Model: GSXR750
Year: -98, -99
Number of Tb: 4
Inside Diameter: 46mm
Center-Center (left to right from behind): 80-80-80mm
Overall Length: 91mm
Outside Diameter (intake): 54mm
Outside Diameter (filter): 54mm
Separate casting: Yes
Injector Make/Model: Keihin,
Flow Rate (45psi/100%): 240cc
Fuel Rail Inside Diameter:
Additional Info: No sec. throttles.

I have it from a reasonably knowledgible source that this is the only setup that does not have "vacuum operated secondary throttles" behind the driver operated main throttles. Does anyone have any information about this? I'd like to find out more about how these secondary throttles work.
According to the specs posted, these also seem to be the biggest throttles around as well.

Yes you are correct, those TBs from the 98-99 GSXR750 dont have secondaries.

However with regard to your main question, the secondaries are there to help control the airspeed in the inlets, just like a slide in a CV carb does. They are controlled by the main suzuki ECU and operated by a stepper motor (I believe its a stepper motor). Thus far most people seem to agree that there is more to be gained by removing the secondaries and their shafts, than leaving them in (even in their stock applications like the GSXR series of bikes that now come with them).

Hope that helps.

Make/Model: Suzuki GSX-R 750
Year: 2002
Number of Tb: 4
Inside Diameter: 42mm
Center-Center: 80mm
Overall Length: 347mm [stock TPS to Throttle Cable Bracket]
Outside Diameter (intake): 48mm
Outside Diameter (filter): 52mm
Separate casting: Yes
Injector Make/Model: Keihin QB28 BBS A
Flow Rate (45psi/100%): (168ml/10 seconds)
Fuel Rail Inside Diameter: 2.4mm
Additional Info: Sec. throttles controlled by ECU.
High Impedence Injectors

http://s94381261.onlinehome.us/240SX/Th ... 20Open.JPG

http://s94381261.onlinehome.us/240SX/Th ... Bottom.JPG

http://s94381261.onlinehome.us/240SX/Th ... Plates.JPG

Devilman wrote:
Yes you are correct, those TBs from the 98-99 GSXR750 dont have secondaries.

However with regard to your main question, the secondaries are there to help control the airspeed in the inlets, just like a slide in a CV carb does. They are controlled by the main suzuki ECU and operated by a stepper motor (I believe its a stepper motor). Thus far most people seem to agree that there is more to be gained by removing the secondaries and their shafts, than leaving them in (even in their stock applications like the GSXR series of bikes that now come with them).

Hope that helps.

You are correct!


Schematic of the GSX-R1000's SDTV (Suzuki Dual Throttle Valve) fuel injection system, which functions like a digital CV carburetor to tame the lurchy off-on throttle response encountered with earlier fuel injection systems.

The 750 is the same..

Info retrieved from here: http://venus.13x.com/roadracingworld/is ... xr1000.htm

I didnt see this thread when I posted this in another:

I got most of these from MCNEWS.com.au, these seemd to be motor-side sizes but I cant really say...

kawasaki:
2005 zx6r : EFI with 4 x 38mm oval throttle bodies
2004 zx10 : 43 mm throttle bodies
2002 zx6r : Fuel injection with 38mm throttle bodies
2002 zx12 : Fuel injection with 46mm throttle bodies

yamaha:
2005 r6 : EFI with 40mm throttle bodies
2004 r1 : 45mm throttle bodies; with primary and secondary butterfly valves
2003 r6 : 38mm throttle bodies

honda:
2006 cbr 1000 : PGM-DSFI electronic fuel injection, 4 x 44mm throttle bodies
2004 cbr 1000 : PGM-DSFI electronic fuel injection, 4 x 44mm throttle bodies
2003 cbr 600 : 40mm throttle bodies

suzuki:
2006 gsxr 750 : 40mm
2003 gsxr 1000 : Keihn electronic fuel injection with 42mm throttle bodies
2001 gsxr 600 : 38mm

I´ll put that in the list and see what happends, maybe someone can come up with some more measurments and/or info.

Thanks to all who are sharing there info and pics on these bike TB´s.

(if only I had seen some of the pictures earlier but "what the heck", it might be fun to modify an other set in some other way later)

Hi all, i've just gotten hold of two sets of 38mm (choke plate size) cbr 600 bodies for my 3.9 rover v8. The engine is in a relatively mild state of tune, do you reckon these will be big enough for it? I'm starting to wonder. . . . . Also, does anyone know if the injectors will be any good and if not if there is any direct fit (no mods required!) bigger injectors available for them? Thankyou all!

Nice manifolds!

I've got the same TB's on my Dolly Sprint. Mine were sourced from a CBR954 and have bluey/green coloured injectors. These are currently making around 40-45hp per cylinder at just over 50% duty cycle....

Here is a set of 2002 gsxr 750 throttles set up for a Nissan ka24e.








Staged sequential injection with COP coming soon