EFI for 50cc-250cc Scooter! (UPDATES!!)

I am modifying this first entry with the accumulated information of this article
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[note: this is not a product plug, I have no association with Ecotrons or their EFI kit. I'm just a regular scooter user who sees the advantage of having EFI on his scooter]

*This article reprinted with the express permission of the author, me.

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Why EFI?

Every one of us loves our little scooters. They are fun, convenient, cheap to operate, easy to work on, and did I say fun? Many of us use them as our primary transportation, scooting all over town on our two wheelers or three wheelers, 50's, 250's, and all sizes in between.

The small scooter engine sips gasoline. That's one reason we ride them. 100 miles per gallon or more. While an SUV might take $100 to fill up, we just borrow their overflow container to fill our tanks.

As we all know, most scooters have carburetors. While this is cheap and effective, it isn't really the ideal option considering the technology we currently have at our disposal. They are inexpensive to produce and easily modified, but they are also touchy, sensitive to environmental changes, and sometimes just don't work well. Some of the most basic issues are resolved by answering the question, "did you clean the carburetor?"

Electronic fuel injection has the potential to make the scooter more reliable, have more power, and get better gas mileage. In other EFI engines this is the case, so why not for our scooters? EFI kits for small engined scooters aren't widely available and remain a dream to many, until now.

A few companies have started making "bolt on" EFI kits made specifically for small engines, from 50cc to 350cc or thereabouts. Since the kits have only been recently available, their actual usefulness and usability have yet to be determined.

Enter me.

I LOVE my scooter. In fact, I'm starting up a scooter rental business this summer to rent and sell scooters. Growing up with EFI cars I am well aware of the reliability and ease of use of EFI systems. I have only been dealing with carburetors for the past year or so, mainly because of this scooter. I would like the reliability and the tunability of an EFI system.

Now before you yell that carburetors are reliable and they are tunable, let me concede those facts. However, you have to be somewhat knowledgeable in how carburetors work in order to tune them. If you are going on a road trip from the seashore over the mountains, you most likely will have to suffer bad engine performance along the way, or suffer a few stops to tune the carburetor to the changing conditions. A properly programmed EFI system will make those changes automatically, by computer, or even a Palm Pilot on the side of the road.

Ecotrons is one company I have come across that manufacturs small engine EFI kits. I have been in contact with Ecotrons and they have sent me a unit to evaluate so I can write this article.

$299 plus shipping. The company Ecotrons is based in WI.

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Again, Why EFI?

To be a little more precise and clear about this, here are some advantages to EFI systems.

• Instant starts
  
• Better throttle response
  
• Better gas mileage
  
• Increased reliability
  
• Cleaner emissions
  
• Easy tuning
  
• Custom timing advance
  
• More overall power
  
• Accurate sensors (RPM, TPS, O2, MAP, and others) - An accurate tachometer isn't generally found on a stock small engine scooter. An aftermarket tach might be cheap, but it won't record your tuning session. Also, an aftermarket gauge cluster might have recording functions, but they are often more than $400.
  
• Ability to fully record all sensor readings and analyze over 600 variables graphically.
  

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4/29/2011

I was awoken to the rap rap rapping,
tap tap tapping
tapping, at my door...

It was the DHL faerie delivering the Ecotrons EFI Kit!


DHL brought me a gift from Hong Kong

The box was packaged very well, everything wrapped nicely in bubble wrap. I was amused by the homemade box though. Who says you can't make the perfect size box for your shipment?


Notice the homemade box but also the bubble wrapped parts

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Delivery Inspection

Some pictures of various parts of the kit:




All the parts nicely laid out

Here are a few quick observations about the kit:

• Nicely made. Some manufacturing defects, but much better than I expected. The wiring harness seems to be wound really well with plastic. All the wires are labeled.
  
  
• The stock throttle cable is too short for the 23mm carb. The overall cable itself is fine, but the exposed part between the anchor and the button is about 1" too short. NOTE: Ecotrons will provide an optional throttle cable in the near future
  
  
  The stock throttle cable installed on the new throttle body - too short
  
  
• The stock airbox won't fit. I have an aftermarket filter I just bought for my scooter but that won't work either. The flute at the entrance to the throttle body flares out to nearly 42mm. Definitely need to get a larger air filter.
  
  
  You can see how the stock airbox snorkel won't fit over the new throttle body opening
  
  
• The throttle body and the new intake plenum bolt together. This makes it easier to buy (or fabricate) a longer intake runner if you want to tune the intake more. I think it might be good to add another 5" or so if possible. It would help with midrange power.
  
  
  You can see how the throttle body and the intake plenum bolt together
  
  
• The oxygen sensor isn't too large, but it is in comparison with the stock exhaust tubing. The ideal location to put the O2 sensor is a few inches down the header. Perhaps an aftermarket exhaust pipe that is about 25% larger width is needed.
  
  
  Looking down the exhaust header/pipe to the oxygen sensor
  
  
• The switch to change modes between CDI programs is kinda cheap. It's an inline lamp plug. I'll replace it with a switch I can embed into the dash and that looks OEM.
  
  
  The Performance switch and DTC lamp
  
  
  I bought this lighted switch from Radio Shack, look cool doesn't it?
  
  
• The kit comes with a CDI that can replace yours to control the timing via ECU
  
  Stock vs. new CDI
  
  
• The kit does NOT come with the USB/Serial adapter shown in the picture.
  

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Pre Install Setup

Before install there are a few things that need to be done:

• Get manual petcock for the gas line
  
• Get another 2 tees for the vacuum lines as there is one less nipple on the TB
  
• Get heavy duty zip ties
  
• Get a new throttle cable or modify your current one
  
• Get quick disconnects for the electronics
  
• Get a nipple or other attachment for the fuel return line to attach to the fuel tank
  
• Get a new switch for the mode/program switching
  
• Get additional wire in case you need to extend some sockets or sensors
  
• Get a free flow filter that can fit over a 44mm tube
  

There are a few other things that I did, including removing casting flash from the inside of the throttle body (smoothing out the bumps with sandpaper) and trimming the rubber of the inside of the air filter connector for better airflow.

In the future I will smooth out the transition between the intake plenum spacer and the intake port on the head. It just takes some JB Weld and some sandpaper. TIP: if you use a smooth roller on the JB Weld when it's no longer tacky but still not yet fully hard, you can smooth the surface out really nicely without having to sand it.


The ports do not match up very well as this kit can support up to a 250cc engine.

I installed the software, ProCAL-SE onto my touch screen netbook and on my desktop. There were a few problems installing on Windows 7, but after a few workarounds I got the software to install properly. The issues have since been fixed with a new software release.

The ECU connects to any Windows based computer using a 9 pin serial port. Nowadays computers aren't made with serial ports. However, a few bucks will get you a USB to Serial adapter that you can plug into any computer. Just be aware that some of the older and cheaper USB/Serial adapters need drivers that aren't readily available for Windows 7.

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Bench Test


Bench testing the Ecotrons EFI system

After going through the instructions and verifying all the parts are present, I wanted to test the ECU to make sure that it was working properly. Following the schematics, I hooked up the ECU to a charged scooter battery and attached all the sensors that I could. When I touched the ignition wire to the +12 pole I heard the fuel pump turn on for 5 seconds. I was able to successfully connect the software and got a realtime readout from the sensors. I twisted the throttle and the readout changed. Everything seems to work.

Now that the brain was verified, I needed to get the rest of the odds and ends sorted out before I could commit to the install.

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Throttle Cable

I originally tried purchasing a new throttle cable to modify. By mistake I bought a Type 1 cable when I need a Type II. The difference is the screw threads at the throttle handle end. It needs them. After I spent an hour carefully cutting 1.5" off the sheathing and reconnecting the sheathing to the attachment assembly, I put it on the scooter and found out that I cut about 1/2" too much! Even with all the adjustment points extended to the maximum it still wasn't enough. I found a brass nut for a 1/4" plumbing fixture, filed out the hole that the trunnion can fit through and fit it as a spacer. Worked fine for the one day I needed it until I got a new one that had the proper length. The one I purchased is 78.7" in length. A 70" cable would be perfect, but the extra 8.7" can fit underneath the floorpan without any trouble.



Proper length throttle cable

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Oxygen Sensor

A trip to the local body shop and $25 got me a bung welded onto my exhaust pipe. The bung came with a screw insert to close the hole if you need to remove the oxygen sensor. It took alot of work to get it attached since the exhaust pipe is so small. We ended up having to weld on extra metal on the sides to marry the bung to the pipe wall and close the gaps on the sides. In the future it would be easier to get a short length of 5/8" pipe and form fit it around the exhaust pipe for a better fit.


The oxygen bung welded onto the exhaust pipe

I decided to place the oxygen sensor in this little cutout underneath the frame. It fits perfectly, and it's somewhat protected from anything on the road, except a huge pothole or speed bump. It was unfortunate but the oxygen sensor covered the access to one of the exhaust studs. It wasn't impossible, but it did take over 20 minutes to tighten that bolt.

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Fuel Petcock

I searched all over for a manually operated fuel petcock that fits our scooters. I tried a dozen parts websites, I visited half a dozen stores. I went to Lowe's and other plumbing stores to see if I could *make* something that worked. I succeed in creating one. It ended up leaking and dumping 1 gallon of gas on the garage floor. I'm still high from the fumes.


My DIY manual petcock that leaked

I ended up mounting this.



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Install

I started the install by removing the seat bucket and a few body panels. I installed the ECU with zip ties on the frame ahead of the valve cover, next to the battery box.

TIP: You really want to buy sturdy zip ties. The ones that come with the kit are fine for vacuum lines, but they will not support the weight of the fuel pump or the ECU. About $10 gets you a bag of 50 heavy duty (longer) zip ties from any home improvement or auto parts store.


ECU installation location

After the ECU was suitably secured, I started installing the different sensors in the proper locations.

In order, left to right, top to bottom:

1. Ground, fuse, CKP Crank Position Sensor, CDI_ctrl control wire
2. +12v, -12v
3. KEYSW Ignition on +12v and relay
4. Ignition on +12v connected to ignition on power (black wire)
5. IAT Intake Air Temp sensor
6. MAP Manifold Absolute Pressure sensor
7. Fuel injector connector
8. Oxygen sensor connector
9. Serial connector




10. CDI replacement harness
11. Power wires connected and tested
12. Engine Coolant Temp sensor location
13. Valve cover
14. Intake Air Temp sensor plugged into air filter
15. Removing old intake gasket
16. Old intake spacer vs. new intake spacer
17. Homemade soldering iron holder
18. Everything installed

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Installation Steps

1. The Reference Ground (GND) wire mounts to the frame. There are wires that are already grounded to the frame next to the battery box, so it's easy to just add the wire. I added a crimp on circular connector for a good solid fit.

The Crank Position Sensor (CKP) attaches to the ignition pickup wire, which is accessible near the crank or in the ECU harness. I used a crimp on connector that splices a blade type socket to an existing wire. That way I could remove the wire without un-soldering if I need to later.



If you want to use the optional CDI to allow the ECU to control the timing, solder the connecting wires into your CDI wiring harness, wire for wire. You can leave both harnesses attached and just splice into the wires. They should match up as long as you have a 6 wire CDI. If your pinout is different, refer to the installation instructions to determine the proper wiring connections. Cut the the Crank Position Sensor wire indicated as above, connecting the (orange) CKP wire to the Crank Position Sensor and the return (grey) PG wire to the CDI harness.

I chose not to install the provided CDI yet, but I will at a future date. Instead of cutting the Crank Postion Sensor wire I spliced into it with the (orange) CKP wire.

NOTE: If you would like to reference the wiring harness diagram, it is provided at the end of this article.

2. The +12v power connects directly to the positive battery terminal, and the -12v ground connects to the battery ground.

3/4. The KEYSW wire connects to a +12 volt wire that is powered when the ignition key is turned on. I spliced the KEYSW wire into the (black) ignition key on wire under the front cowling of the scooter. Originally I wired it into what I thought was the tail light but was actually the brake light. When I would release the brake after starting, the ECU would shut down. D'oh!

5. The Intake Air Temp (IAT) sensor was easy to mount. I zip tied it to the frame and poked a hole through the foam air filter for the sensor tip. I also put the Crankcase Ventilation return line through a hole in the foam air filter as well, as seen in the picture 14 above.

6. The Manifold Absolute Pressure (MAP) mounts at a convenient location on the frame. It connects to the intake manifold vacuum lines through a T connector.

7. The Throttle Position Sensor (TPS) plugs into the socket on the TB.

8. The Oxygen Sensor harness plugs into the oxygen sensor on the exhaust pipe.

12. The Engine Coolant Temperature (ECT) sensor attaches to the engine by any bolt that is not in a direct airflow. If you have a liquid cooled engine, it would be mounted to the cooling system.

I installed the serial connector on the frame by the fuel pump. It is easy to get to and protected from the weather. It might be worth it to cut a hole in the seat bucket and affix the connector to the hole, so it is accessible from inside the seat bucket. That way the travelling laptop computer could be locked inside for security and still have data access to the ECU.


Serial cable data connector

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Fuel System

The fuel system is a little more complicated to install. The fuel pump needs to be lower than the fuel petcock but higher than the fuel injector. That way gravity will assist the fuel flow and there shouldn't be fuel starvation issues.


Choosing the location for the fuel pump


Fuel pump and pressure regulator


Make sure the fuel lines clear all obstacles like the seat bucket mounts


Location of the manual petcock and fuel filter


Everything installed



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Fuel Return Line

This kit requires the fuel return line to be installed into the fuel tank. This involves draining the tank and drilling a hole for the fuel return to connect to. Instead of just shoving a fuel line through a hole and covering it with RTV sealant, I decided to install a nice nipple for a more professional install.


Choosing the best location for the fuel return line


Poly nipple I bought at Lowe's for $2

I decided on a location that would be on top to minimize fuel leakage, a spot that was easily accessible, and one that is protected from the seat bucket. I originally planned on using a backing screw to hold the nipple onto the tank. It turns out that it fit so well with just the RTV sealant I didn't bother with the nut.


Hole drilled for the fuel return nipple


Completed fuel return line nipple

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Initial Test

If you have everything installed up to this point, turn on the ignition key. Do not start the engine yet. The fuel pump should power on for about 6 seconds.

Fuel Economy

Date ----- Odometer -------- Gas -------- MPG
??/??/?? 733.1 - 757.3 ---? gal --------- ? ------- Gas tank leaked! Have to start over.
??/??/?? 757.3 - 856.4 ---- 1.001 gal --- 99.00 --- Hard cold starting
06/11/11 856.4 - 958.2 ---- 1.083 gal --- 93.33 --- Fuel pump leak and overfilled!
07/22/11 958.2 - 1046.5 --- 0.962 gal --- 91.78 --- Hard starting issues
08/09/11 1046.5 - 1152.3 --- 0.972 gal --- 108.8 --- More TRUE numbers
08/20/11 1152.3 - 1249.0 --- 0.885 gal --- 109.2 --- Awesome gas mileage!

LIFETIME: 491.7 miles --- 4.903 gal --- 100.28 MPG


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Potential Issues

There has been some question of the electrical requirements for the kit. I have been contacted by the owner of the company and he sent me the following info:



They are aware of possible charging issues. I haven't heard any word from him yet as to how much testing they've done specifically with a 50cc motor, but I'm sure it's not much. This is a learning experience for all.

There have been some suggestions for upgrading the stator. I suggested the possibility of a smaller fuel pump or even a backup battery if you need to idle alot or need to kickstart the bike. I'm sure others can come up with better contingency plans.

UPDATE: Ecotrons is in development for a smaller fuel pump that draws less power. News of the release will happen shortly

I have also swapped out the brake light bulb (35w) with an LED light. Power and charging issues have disappeared!


Wiring Harness Diagram

This image is automatically resized. A larger version is here: scootdawg.proboards.com/index.cgi?action=downloadattachment&board=discussion&thread=37715&post=380314&key=Nuir61oCivYPNXPkYbia
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