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YZ Fuel Injection Spy Photo

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Posted by: xsnrg

I was leafing through some MX mags last night and saw either in DirtRider or in MXA a "spy photo" of the Japan Yamaha Factory MX team's YZ with Fuel Injection. Anyone heard or know more about it? Looks like it will be coming to us soon. Can't imagine it will be something just for 'works' bikes.


Posted by: BMWPower

Thats great!!! do you have any pics?


Posted by: xsnrg

No, like I said, just saw it in a magazine at the bookstore. Seems the factory team racing MX in Japan is riding YZs equipped with it. That's all I know. Looked like a black box where the carb would be that had rounded corners.


Posted by: MX851

Here you go

Click here


Posted by: xsnrg

That's it. Dirt Rider, pg 22.


Posted by: Pete Payne

Is taht a choke knob ?? or maybe a hot start knob ??? Fuel injection wouln't need this ????


Posted by: bedell99

It's probably hot start.

Erik


Posted by: MX851

It may be a choke knob. A choke knob would be needed in this case because it looks to be only a prototype and it can not start correctly with a cold motor. The other thing with FI is that you will need to have TPS, CPS, CKPS, and either a engine or coolant temperature censor.


Posted by: BMWPower

O it's a 4-stroke. that sucks


Posted by: Rich Rohrich

Quote:
Originally Posted by MX851
It may be a choke knob. A choke knob would be needed in this case because it looks to be only a prototype and it can not start correctly with a cold motor.


EFI systems do not use manual choke systems.


Posted by: MX851

oops


Posted by: tony91

Quote:
Originally Posted by Rich Rohrich
EFI systems do not use manual choke systems.


Rich,

Not trying to start a pissing match here but.....my RC51 is EFI with a manual choke.

Tony


Posted by: Rich Rohrich

Quote:
Originally Posted by tony91
Rich,

Not trying to start a pissing match here but.....my RC51 is EFI with a manual choke.

Tony



Thanks for the info Tony. I learn something new everyday.

On most conventional EFI systems the onboard sensors will tell the control unit that the engine is cold and it will modify the injector pulse width and raise the idle speed to compensate for the temps, and change them accordingly as the engine warms up. . After I saw your post I did some research (note to self .. it's always better to research BEFORE touching the keyboard ) and I found out that as you pointed out the RC51 doesn't use this electronic "choke" system, it has a manual plunger system not all that different from carbs. I assume this is to ensure the bike can be started at warmed up regardless of the extent of the engine mods performed. Anyone who has played much with EFI based engines knows this can be a real issue. Not a bad idea when you think about it. Those Honda guys are always thinking.

So MX851, you are probably corrrect in your assumption. It's very likely that Yamaha adopted the same approach.


Posted by: steve.emma

maybe they did that so they wouldnt have to use a coolant temp sensor (for the cold start phase) and so the ecu could be made more simple.
the big question for me about this yz efi system is that they say no sign of a battery, and a battery would be rather heavy for racing,so if no battery then how does it start?... can of ether?!?!


Posted by: MX851

The battery to run the EFI system would not have to be that large and would not weigh that much. Plus that little extra weight would be worth it compared to the fact that your air fuel mixture would be correct at all times.

But I don't think that the system could be run on a couple AAs.


Posted by: KDXruss

None of this seems like news to me. The July 05 issue of Trail Rider mag has a write up on the 06? Sherco 4.5i, It's a 4 stroke 450cc offroad bike with a Magneti Marelli EFI system, no choke lever and a 7 amp battery under the seat.
Dirt Bike Oct. 05 tested the Gas Gas EC450 with EFI and a Montesa trials bike with a Honda motor and Honda EFI.
The trials bike has no battery, "It has fewer moving parts than you would think and does not require a battery. When you start the kickstarter stroke, a high performance generator and capacitor instantly produce enough electrical power to run the PGM-FI and fuel pump (which is located in the fuel tank)"


Posted by: MX851

No, none of this is new news, there have been many bikes that have used fuel injection(cannondale). But this time it is a big deal because they are applying the technology to a bike that is already a good bike to just make it better.


Posted by: Dirt Bike Dan

I believe yamaha's raptor (700cc? atv) has FI. Won't be long until the bikes do as well.
Also, I might add I was greatly disappointed when I saw the picture of a four-stroke.


Posted by: hellbertos

When I saw this thread I was SO excited (still am actually) that one of the big 5 is testing FI on a flagship motocrosser... but HUGELY disappointed to see it was not on a 2T. However, given that Yamaha has excellent 2T's which apparently still sell fairly well, perhaps all is not lost...

A long shot? Maybe... but while everyone else gave up on 2Ts, they revamped theirs. Perhaps they will do it again.. and make it emissions friendly!! I will be on the waiting list for a green sticker YZ 2T!!


Posted by: CaptainObvious

Quote:
Originally Posted by Rich Rohrich
I found out that as you pointed out the RC51 doesn't use this electronic "choke" system, it has a manual plunger system not all that different from carbs.

I always thought that was an enrichment circuit.


Posted by: OZKX250

Some EFI models have a high idle circuit (albeit older ones like the GPZ's) for cold starting if they dont run all the sensors that the newer models do eg R1 or CBR's. It could just be a real basic EFI system to work out if it will handle the big shocks from jumping or the constant on and off the throttle needed in MX rather than a more so constant throttle position on road bikes.


Posted by: Ford357

Now those expensive pipes will need to be cusotm fitted with o2 sensors


Posted by: phranticness

Ya I don't understand what the "choke" nob is all about either, FI cannot use a choke, the pcm just enrichens the mixture. unless that nob was just for disguise or it took the place of a CTS, a switch that just manually told the pcm the moter was cold and to enrichen. hmmmmmmmmm, we'll probably never know.


Posted by: blackduc98

All my FI bikes have a "choke" control on the handle bar, but in fact it is nothing more than idle stop control.

If you will permit me to engage in a bit of wild speculation: I'm thinking that if you took a standard carb and plugged up all jets and circuits except for the starting circuit which is operated by the choke knob, then you could kill 2 birds with 1 stone. The choke circuit should be enough to kick-start the motor with the throttle closed, so you don't need a battery for starting. Once the motor is spinning you've got enough electricity to power an electric fuel pump, fuel injector solenoids, MAP sensor, temp sensor, O2 sensor, etc., and the EFI computer. After you shut off the choke, the carb body becomes simply a throttle body, so all you need to do is attach an injector downstream of the throttle slide. So basically you end up with a carb/FI hybrid that eliminates the need for a battery.


Posted by: steve.emma

yes you are right that could work but then you would have a carb/throttle body unit that would be far more complicated and more expensive to produce than a simple injection throttle body in the first place. plus you would also have to have a gravity feed for fuel to the carb (as in a normal bike) as well as a high pressure feed (via the fuel pump) for the injection to operate.... see what im saying? the simplest way to get cold start enrichment (if you even really need it for racing) is to use a temp sensor as allready disscused by other posts.



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