New Zongshen RX3 (ZS250GY-3) Dual Sport

[Weldangrind]

Originally Posted by MotoJ

For someone who has no experience with EFI, just how does one "re-map" a fuel injection system? I'm experienced with tuning and re-jetting carbs, but I've never owned anything with EFI. The newfangled electronic stuff on this bike is the only thing that intimidates me.

I've done some reading on this topic, and here's how I think it works:

In any gas engine, you're striving for the optimal air / fuel (AF) ratio, whether with a carb or FI. The beauty of FI is the ability to feed back the oxygen content in the exhaust, so the PCM can make changes on the fly.

A standard FI system will work at maintaining 14.7:1 AF, but that is the best all-around number that factors power, efficiency and emissions. As you move a little richer in the ratio (say around 12.5:1), you tend to increase power.

To make the mixture a little richer, you alter the pulse width, which is essentially the time that a fuel injector remains open, and that determines the amount of fuel per intake stroke. It would take a dyno to quantify results, so you'd need to keep a close eye on the A/F ratio and the temperature as you try to achieve maximum power.

You can also alter ignition advance, but that requires the addition of a knock sensor to avoid detonating the engine to pieces. Again, careful monitoring of the engine while the bike is on the dyno is the key.

All of the changes are done with software, while the bike is connected to a laptop.

Make sense?

[jimjr21]

Originally Posted by Weldangrind

I've done some reading on this topic, and here's how I think it works:

In any gas engine, you're striving for the optimal air / fuel (AF) ratio, whether with a carb or FI. The beauty of FI is the ability to feed back the oxygen content in the exhaust, so the PCM can make changes on the fly.

A standard FI system will work at maintaining 14.7:1 AF, but that is the best all-around number that factors power, efficiency and emissions. As you move a little richer in the ratio (say around 12.5:1), you tend to increase power.

To make the mixture a little richer, you alter the pulse width, which is essentially the time that a fuel injector remains open, and that determines the amount of fuel per intake stroke. It would take a dyno to quantify results, so you'd need to keep a close eye on the A/F ratio and the temperature as you try to achieve maximum power.

You can also alter ignition advance, but that requires the addition of a knock sensor to avoid detonating the engine to pieces. Again, careful monitoring of the engine while the bike is on the dyno is the key.

All of the changes are done with software, while the bike is connected to a laptop.

Make sense?

Some injector systems also have variable input pressure along with open time.

Stoichiometric ratio depends on the fuel. Pure gasoline is 14.7:1. However most fuel in the pumps these days is E10 which is stoichiometric at 14.1:1. Pure ethanol is 9.0:1.

So again being able to alter the maps would be very nice.

[jimjr21]

Originally Posted by MotoJ

Thanks for the porn!

For someone who has no experience with EFI, just how does one "re-map" a fuel injection system? I'm experienced with tuning and re-jetting carbs, but I've never owned anything with EFI. The newfangled electronic stuff on this bike is the only thing that intimidates me.

Signed,
Unfrozen Caveman Biker

Programing EFI is really dependent on the computer program that has the ability to talk to the EFI module and rewrite the code.

Difficulty lies in knowing how all the different maps work together.

I am not familiar with the system used on this engine but would be fairly simple. With an O2 sensor is most likely an open loop system. These can be very nice where it the system reads the oxygen levels in the exhaust then makes a change map based on readings that vary the base map that is selected from inputs like throttle position and rpm.

I hope the EFI program is not too expensive to license a copy and works easily.

[SpudRider]

Originally Posted by MotoJ

Thanks for the porn!

For someone who has no experience with EFI, just how does one "re-map" a fuel injection system? I'm experienced with tuning and re-jetting carbs, but I've never owned anything with EFI. The newfangled electronic stuff on this bike is the only thing that intimidates me.

Signed,
Unfrozen Caveman Biker

You're welcome.

The Dobeck EJK (Electronic Jet Kit) allows you to enrich, or lean the fuel mixture to your preference for idle/cruise, acceleration, and full throttle. Therefore, you can tailor the bike's fuel economy and performance exactly as you wish, and easily change any of these settings at your convenience.

[Weldangrind]

Originally Posted by SpudRider

AJP selected a nice location for the O2 sensor, which can be seen at the lower left of the photograph.

That would be a worthy modification to the RX3.

[SpudRider]

Dobeck uses load based technology to program its EJK controllers.

[SpudRider]

Here is a video showing how to install the EJK controller on a Honda CRF250L. The installation would be similar on a Zongshen RX3.

[SpudRider]

Dobeck also offers the new, AFR+ controller for the Honda CRF250L. I don't know if Dobeck would offer this option for the Zongshen RX3. However, the following video shows the difference between the EJK controller and the AFR+ controller.

[SpudRider]

Here is a video which more thoroughly demonstrates the AFR+ adjustment modes.

[Wolftrax]

Spud, PM sent

[SpudRider]

Originally Posted by Wolftrax

Spud, PM sent

I got your PM, Mark. Thank you.

[Wolftrax]

I have the EJK on my Honda and it is simple yet very effective way to dial the EFI in. The honda had a lean stumble off idle and the EJK fixed it. I also did a Stage 1 on my honda and was able to enrich my fuel over the entire throttle. Great product that does away with all the programming hassles.

[SpudRider]

Originally Posted by Wolftrax

I have the EJK on my Honda and it is simple yet very effective way to dial the EFI in. The honda had a lean stumble off idle and the EJK fixed it. I also did a Stage 1 on my honda and was able to enrich my fuel over the entire throttle. Great product that does away with all the programming hassles.

I assume we are planning to stick with the RX3 stock muffler, and not make any air box modifications. I'll know more about our options after the RX3 motorcycles arrive.

[Wolftrax]

Originally Posted by SpudRider

I assume we are planning to stick with the RX3 stock muffler, and not make any air box modifications. I'll know more about our options after the RX3 motorcycles arrive.

The CRF250L has recommended settings for stock, Stage1 and big bore. I think setting it up as stock will be the baseline. The CRF EJK only allows you to add fuel. I noticed that the EJK for Delphi equipped HD's allows for adding as well as subtracting fuel. More than likely I'll probably open up the airbox and knock the cat out if it has one.

[SpudRider]

Originally Posted by Wolftrax

The CRF250L has recommended settings for stock, Stage1 and big bore. I think setting it up as stock will be the baseline. The CRF EJK only allows you to add fuel. I noticed that the EJK for Delphi equipped HD's allows for adding as well as subtracting fuel. More than likely I'll probably open up the airbox and knock the cat out if it has one.

I can see where the AFR+ controller would greatly facilitate fine tuning the final adjustments, since it includes an AFR meter. If using the EJK controller, I can also see where it would be best to first optimize the stock setup. After the stock setup was optimized, one could then alter the air box, and play with the settings until it was optimized. Finally, one could remove the catalytic converter, if present, and optimize the final settings.