Ok here is a draft of the project. I am not done but I hope this helps everyone.
The following is how I Sam Cotter fuel injected my 1998 DRSE 350
DR 350 Fuel injection project is as follows. The whole concept of the project began with what else surfing the internet. I was intent on learning about direct injection theory for 2 strokes. I was quickly side tracked to the megasquirt forum which is a diy fuel injection forum for the megasquirt diy ECU. At first I was intent on using the “microsquirt” but after realizing it was not going to be released soon enough I decided to go with a tried and proven “megasquirt” Just to give some back ground the megasquirt is the first generation of diy ECU’s by Bolling and Grippo. They are currently in the process of releasing what is called the micrsquirt a very small pre built user programmable ECU. In January of 07 I purchased a Megagsuirt I ver 2.2. It cost $140.00 for the kit. What you get is a bare circuit board and a bunch of labeled bags with all the electronic things that make the world go round. Also I purchased a kit for what is called the stimulator. It is not essential that you get this but I highly recommend it. I am not an electronics person so to be able to build the stimulator kit first was a big boost in confidence that I could build the ECU. Getting the ECU and the stimulator built was not that hard at all. All you need is some time, 10-12 hours total for a newbie electronics person, a solder pen, solder, and a well lit work area. I built mine right in front of my PC so I could read the online instructions as I went. There is not a hard copy of the instruction that come with the kit you have to either print out all the instructions or be online while you build either way works fine. I can’t say that there was anything too difficult about the ECU build just be careful soldering.
Once the ECU was built I used the stimulator to test it out and it functioned perfectly. Needless to say I was thrilled that I had gotten it all together without a glitch.
After the ECU was built I proceeded to collect all the other items and hardware that would be need to install the system on the DR.
Other items that are needed depending on your particular conversion are; a fuel pump, throttle position sensor, oxygen sensor, coolant and air temperature sensors, fuel regulator, fuel injector, wire, solenoids, electrical connectors, someway to adapt a throttle body to your application, and above all time.
I will give descriptions of what I used for each of the aforementioned items.
Fuel pump EBay I found a guy that had over 100 high pressure EFI fuel pumps for what he claimed were to a Apprila fuel injected scooter. I bought two $12 each. When I got them I realized they were in tank style and not inline. I had two options at that point, I could cut open my tank and try to come up with a way mount the pump in the tank or find an inline pump that would work. I decided to source an inline pump. If you go this route do not get the MSD in line pump it’s huge, I bought one from Jegs took one look at it and sent it back. Now I am back to my eBay specials. I decided to make an adapter that will turn my in tank to an inline pump. A side note on fuel pumps, from what I understand the Cannondale fuel pump it able to be gotten from NAPA using a ford ranger part number. The Cdale pump is suppose to by an inline set up. After making the adapter even though it worked fine if I do another bike I will look into the C-dale pump. I also bought an adjustable fuel pressure regulator off eBay; this was a new item that is oriented after all the street racers. I would like it to a bit smaller but for now it is working great. For the temp sensors I bought off the shelf GM air temp and coolant temp sensors from DIY autotune. They were cheap and new. The core of the hardware was a pair of throttle bodies off a 2003 SV 650. I thought this would be a good donor for my bike due to the fact that the 650 is a twin and half of 650 is 325 just inline with what I need. I was able to get a pair of these off eBay witch came with fuel injectors and TPS. When I received them I first thought I was all set but after trying some fitting I realized I would have to either make an adapter or bite the bullet and machine a throttle body from scratch to fit my application. I did not want to but I realized it would be the quickest way as opposed to trial fitting of misilaneaous TB’s. This was one of the few set backs that slowed the project. Only having so much time I had to work on TB after work hours and a few Sundays but I got it done. I do not want anyone to think that it is mandatory to machine a TB but in my case it was the shortest cheapest solution. I am a fully capable machinist that has access to a full CNC shop plus plenty of support equipment. When it’s all said and done I have a custom machined TB that is more portly than a donor. One of the few benefits of machining my own TB was that I was able to give the injector location my personnel feeling on best placement. I chose an underside 45 degree angle thinking that the effect of gravity and the velocity of the incoming air would not let the fuel pool at anytime. Only a theory but at least I was able to try it. Also by making my own TB was able to integrate the existing cable set up off the stock DR carb. Once the TB was done it was time to start the installation.
First I mounted the TB. To do this I had previously took off the seat, rear fender, airbox, I unbolted the voltage regulator, unbolted the shock reservoir, and anything else that was in the way of having full access to the intake area. While I had the air box off I cleaned it to factory specs. I installed the TB at the intake. I attached the throttle cables and checked operation. I then reinstalled all the items that I had taken off. Now at this point I had a bike with a throttle body installed but nothing installed to tell it what to do. This is where it can get tricky. I you are going to do the same bike as me you can follow what I did exactly. If anyone reading this has a better way to do something that I did by all means let me know what it is.
There are several main inputs that MS needs to function. They are with no order of importance: TPS, MAP signal, ambient air temp, engine temp, O2, some indication that an ignition event occurred. I will go through in the ore that I listed them. TPS or throttle position sensor is exactly what it sounds like the position of the throttle. These are common place on non fuel injected bikes. All a TPS is is a potentiometer. It varies its voltage out put based on where it is turned to. The ECU uses this voltage reading to know where the throttle is. I used the TPS that came with my donor TB’s. When I do another MS conversion I will use a standard GM tps due to ease of procurement and connector availability. The Mikuni TPS that I have is fine but if I ever had to replace it I would pay dearly for it at the Suzuki parts counter and I do not have the mating connector only small solderless terminals.
The MAP signal is not all that important for my application. I say this with much room for opinions. I am currently running what is called Alpha-N algorithm. This does not take into account the varying pressure difference from the engine to determine how much fuel to inject. What Alpha-N does is use the TPS and RPM as the main determining factors in determining how much fuel to inject. Some people will say this is crude but from what I have read this is very effective way to inject a small single cylinder engine. From what I understand a small single does not create a bunch of pressure difference through its rpm range.
For the temp sensors I went with standard GM of the shelf stuff. They are cheap durable and widely available. I bought it from a place called DIY Autotune.
For the O2 sensor I am currently running what is called a narrow band single wire non heated O2 sensor. It cost $18 at AutoZone and has a million applications Bosch # 11027. I also bought what is called a wide band set up. This was fairly expensive $200. The difference between the two is the narrow band can only tell the ECU if you are rich or lean but not by how much. The wide band tells the ECU how much you are rich or lean. Then benefit is when using the autotune function you can quickly dial in the proper VE numbers. I have only installed the narrow band so far because I still am learning the whole system so I do not want to prematurely jump into to anything until I really know what’s going on. So far I am very pleased with the cheap narrow band. The discussion of what O2 sensor to use could go on forever but like I said before so far I am happy with the narrow band. When I get the confidence to install the wide band I am sure I will see the benefit. Also after a wide band is installed to dial in the tuning you can remove it and just run a Narrow to keep a check on the air fuel ratio AFR.
The ignition input was pretty tough to get working. The megasquirt needs to know that an ignition event occurred to inject fuel. For each ignition event that occurs MS injects an appropriate amount of fuel based on RPM, TPS, air temp, motor temp, and air pressure. The MS that I used is not directly compatible with CDI ignitions. The basic way the MSI gets an ignition signal is from the negative post on the coil. This won’t work with a CDI ignition. I spent two weekends try to come up with an ignition signal. I was getting disappointed. I finally thought about the tach that came stock on the bike, which has to work off an ignition signal some how. I used a multimeter while cranking the bike over and finally found a source for the ignition signal. There is a chip on the circuit board for the tach that puts out what MS needs. I can not say anything else then that because I have no idea what this chip does. All I know it make MS give fuel to my motor. I will post a pic of what I did to connect this pin on the chip to my MS. For a description all I did was solder in a lead so I could tie it into MS. I know this is vague but for people who are going to do this mod PM me and I will get in touch with you.
Ok now for the fun part, make it run. To do this I install the pure basics. What I mean by that is I did not co anything permanent that did not need to be. All that really needed to be permanent was the TB and air box set up. Everything else could just hang there. About an hour of hooking stuff up and I was read to hit the button. Naturally I was quite excited. I cranked for a bit and nothing. A bit more and nothing. What I figured out was that the fuel pump did not have a prime yet. The best way to do this is blow into the gas cap vent hose to pressurize the tank. A little more cranking and VROOM. It died rite out but it started. Now is where the tuning begins. Why did it die? Well this is where your particular background comes into play. Do you have enough knowledge on what a motor needs to run; can you identify what a sputtering motor is looking for? I did some adjustments with the laptop and got it to idle nicely in 15 minutes. I was thrilled I thought to my self this has to be the world’s first fuel injected DR 350.