Does anybody know how Yamaha's new throttle bodies work?

Petrovich · Post by **Petrovich** » Mon Mar 06, 2006 1:53 pm

Picked up a set for my GS for cheap. All fine, the sensors hook up real nice and easy, BUT there's this whole suction-piston setup thing. There's a little cylinder on top of those throttle bodies, and shields before the throttles (like in carburetors). So far I could not find out how it hinders me, other than the shields being somewhat obstructive (although I think they retract under vacuum). But I just want to make sure that I don't need to make any special accomodations for this throttle body.
It came out of an R6, and I'm going to be using it with 3.0 MSII and an in-tank fuel pump.
Also, the thing has a vacuum line going to the fuel pressure regulator - is this normal?...

keithmac · Post by **keithmac** » Mon Mar 06, 2006 3:09 pm

Can you post a pic?

Petrovich · Post by **Petrovich** » Tue Mar 07, 2006 9:21 pm

Attached...

nobbi1977 · Post by **nobbi1977** » Wed Mar 08, 2006 8:36 am

Hi

If this is the same sort of thing as my CBR bodies then the thing on the top is
Idle/warm up and works by bleeding air through bypass holes. if you look at the inlet side of the bodies there should be some small holes the go to the outlet side of the butterfly.

the other things are to keep air flow at maximum velocity, so when you slam the throttle open they open more slowly to keep air speed up. I think they are like the slides on an old CV carb

Petrovich · Post by **Petrovich** » Wed Mar 08, 2006 1:10 pm

Ok, that sounds good... But how do you control the warm-up thingie? It has no cables going to it, just two hoses and that's it.
BTW, there's an idle adjustment screw also,

evolotion · Post by **evolotion** » Wed Mar 08, 2006 2:08 pm

Petrovich wrote:Ok, that sounds good... But how do you control the warm-up thingie? It has no cables going to it, just two hoses and that's it.
BTW, there's an idle adjustment screw also,

i know nothign about this setup, but i'd hazard a guess engine coolant just goes through the hoses and the valve thing is some kind of thermostat. try hooking it up to the hot tap in your house(if you think itl be alright to put water through it) and see??

nobbi1977 · Post by **nobbi1977** » Wed Mar 08, 2006 2:36 pm

I think your correct about the coolant controled warmup. i am sure it could be replaced with a stepper motor if you wanted a lower idle, most bikes tend to tick over quite high (1.5-3k) and than drop as they warm up.

Petrovich · Post by **Petrovich** » Wed Mar 08, 2006 6:28 pm

Well, my GS is aircooled

But I'll try the cold/hot water trick, if it works I'll try to run my oil line through that, or something of that sort.

nobbi1977 · Post by **nobbi1977** » Thu Mar 09, 2006 12:34 am

Yam bits on a Suzuki!!!!!!

I would just rig it up to the choke cable you have now.

nobbi1977 · Post by **nobbi1977** » Fri Mar 10, 2006 6:57 am

Hi

Was surfing for other bits and thought about this thread.

try here for R6 shop manuals

They should give you an idea of what links to what

Petrovich · Post by **Petrovich** » Fri Mar 10, 2006 8:15 am

Thanks for the link! This should help me out with wiring. I got the fuel pump yesterday, so hopefully I'll begin tuning this weekend, if I sort my ignition issues by then.
As for yamaha bits... Suzuki throttle bodies are almost double the price, for some reason...
Plus, those weird slide thingies are starting to grow on me

nobbi1977 · Post by **nobbi1977** » Sat Mar 11, 2006 7:33 am

The Suzi bodies are better spaced to fit on a DOCE manifold so the car guys love them, hence the price.

smurph · Post by **smurph** » Sun Jun 18, 2006 7:56 pm

Those slides keep air velocity high. A variable venturi, so to speak. Look at the bottom of the black slides and you will see a air bleed hole there. As the air flow through the thottle body increases, a siphon effect is applied to the air bleed. This creates a pressure drop inside the pot that overcomes the spring pressure and raises the slide. The external tubes should not be connected to any vacuume source. Instead, they are connected to a filtered atmoshperic pressure air source (air box) and are there merely to keep pressure off the back side of the diaphram. The correct orientation of the throttle bodies is diaphram up, bleed hole down. In other words, the slide should raise, not lower.

The R6 injector is a nice unit. The slides should allow for the throttle bodies to be used on smaller displacement engines or engines that are not capable of the air flow that the R6 engine is. And it should make for easier tuning.

Also, spacing is not so much of an issue as each throttle body is it's own seperate unit. You and easily space them apart with bushings. I have made up a set of R6 throttle bodies that are properly spaced for an RZ350 here.

Steve

FIntruder · Post by **FIntruder** » Thu Jul 13, 2006 1:55 pm

The R6 throttle bodies are CV, constant velocity. When you open the butterfly it gives the diaphram vacumn and the diaphram is what opens the slide. It only opens as much as the engine needs and is more accurate in the carburator world than direct pull or flatslides. This is the only bike I've seen with a CV throttle body set up. I'd like to know Yamaha's reason for doing this.

FIntruder · Post by **FIntruder** » Thu Jul 13, 2006 6:24 pm

I guess what I meant by what Yamaha's reason for doing this was why on the R6 but not R1 or not by any other manufacturer. Does EFI react quickly enough so that a bog is avoided when the throttle is quickly whacked open?