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Participants Cha0z97
Skills Mechanics, Electronics, Soldering, megasquirt
Status Finished
Niche Electronics
Purpose Fun
Tool No
Location Nurdspace
Cost Priceless
Tool category


Cytherea.jpg {{#if:No | [[Tool Owner::{{{ProjectParticipants}}} | }} {{#if:No | [[Tool Cost::Priceless | }}


  • Assembling the ECU
  • Fitting the fuel tank with a fuel pump
  • Building the cable loom that ties the whole thing together
  • Aquiring, calibrating and fitting various sensors
  • Aquiring and mounting the trigger wheel
  • Machining a custom fuel rail out of aluminium extrusion
  • Removing the carburettors
  • Mountin throttlebodies from a different bike
  • 3D print a prototype of a simple mountpoint for the trottle cables
  • Having said design machined by a friend
  • Having said design laser cut by profzon (y)
  • And probably some more

Assembling the ECU

Assembling the ECU wasn't that hard. I ordered a kit off of which included the PCB, all the components and the casing. I also orderd to stimboard, used to simulate different sensors, and actuators. Assembly was pretty straight-forward, as the instructions were very clear (steps) and it would have you test the board at different stages of assembly. I took particular care in soldering everything, as it's supposed to last and I dread the idea of having to find a cold joint on the ECU.

One cool feature of the ECU is that it comes with a proto area in which you can hack your own cool features. In my case I used it to build support for a second ignition coil, the ECU comes with support for just one by default. I also added a transistor to drive the tachometer from the ECU.

Another cool feature is that is comes with support for Hall sensors, VR sensor and a thingamagic sensor to let the ECU know about the engine speed and position. The type of sensor determines how to assemble the board, so it comes with different "pathways" which you can enable/disable by bridging PCB traces or not.

Throttle bodies

Throttle bodies are the place where the fuel meets the air for the first time, setting themselves up for an explosive relationship. We'll need some way of controlling them, therefore throttle valves have been invented. Throttlebodies therefore allow for passage of air, come with a mounting hole for the fuel injector and have a throttle valve fitted. In my case, I didn't have holes for injectors, so rather than drilling them myself, I want to look for a bike which had them already. My bike is a Suzuki Bandit 600, so I deemed it natural to look for a Suzuki 600cc injected bike. Enter the GSX-r 600 SRAD.

The throttlebodies are separate units fitted next to eachother on two rails. They are mounted with rubber rings to the engineblock. This was very fortunate for me, because the spacing between the cilinders of the GSX-r is not the same as on a bandit. So, no hacksaw needed in this case :)

One sucky thing which turned out to be a pain in the ass was finding the right rings. The rings that came with the TB's didn't fit my bike and the rings that came with my bike didn't fit the TB's. Fortunately, with some careful measuring, it turned out that the rings of 1989 1200 cc GSF Katana would suit my needs, and they did!

So, now we have an engine block with mounted throttle bodies

Fitting the fuel pump

In order to get the fuel through the injectors one needs to have some pressure. Unfortunately, my bike didn't have a pump. Rather, fuel would just drip into the carburattors when the valve was engaged, and that's about it. So, I had to get a pump inside somehow. First I had to figure out what pressure I needed, turns out it's pretty much all the same, (3bar) so I got an pump from a Yamaha R1 from the salvage yard and did some guestimation about the size and wether or not it would fit. So, got the pump, but now how to fit it? Luckily I have a friend working in a metal shop, and he was kind enough to machine a flange on which to mount the pump. Now, the flange had to be welded onto the tank. For this I contacted a welder, as I don't have the required skill to pull this off. Unfortunateley, the welder didn't have it as well, as shown by the fuel dripping from the seams, so I had to have another welder redo the job. It took some effort, but I ended up with a fuel pump in the tank! (and no leaks)

Machining a custom fuel rail out of aluminium extrusion

Now that we have the tank + pump, how do we get the fuel to the engine? This is done by means of a fuel rail. A fuel rail is a hollow piece of metal with holes drilled into them that house the injectors. The injectors are put into their sockets and clamped onto the the throttle bodies by the fuel rail. The fuel rail is then connected to the fuel pump.

As I said earlier, the spacing between the cilinders of the GSX-r and the Bandit aren't the same. The GSX-r uses 100mm spacing between all cilinders, whereas the Bandit uses 100mm between the outermost cilinders, but 110 mm between the innermost. The reason for this is that the chain that drives the cams in located in the middle in the case of the Bandit, and on the side in the case of the GSX-r. So I had to bridge a gap. Mounting the TB's wasn't a big deal, I just had to cut a small bus in two, and using them as spacers. However, this also meant I couldn't use the fuel rail of the GSX-r. Which was a bit of a bitch, as now I had to create my own.

Machining a fuel rail isn't a big deal as it turned out. I drew up some plans in autocad, got myself a column drill, orded the extrusion, thread cutters, the right drills and off I went. I used special half inch bolts as end caps, and used the fuel hose mount of the GSX-r. Luckily I did it right the first time, using a slow speed setting on the drill, using machine oil to cool the drill and let it do its work. This is in order to reduce play, which could form a problem when inserting the injectors.

@ The tuner's

The 29th of may I took the bike to the tuner's. Right off the bat the tuner mentioned that the engine wasn't running on all fours. Strange, I thought it was, but I took his word for it. We started tuning anyway. Him operating the bike, me operating the tuning software. After a couple of runs, turns out the bike was running too lean. So we gave it some more fuel. Some more runs, and gradually the outputted power was climbing. Unfortunately, the bike wouldn't climb past 8000-9000 RPM. The reason was unknown, but it appeared to be a hardware problem. This is where we stopped as it made no sense to continue. This was a bit of a disappointment. I thought all problems were sorted, but apperently I was left with two.

  • Bike not running on all fours
  • Engine not revving past ~9000 RPM

Solving the remaining problems

The remaining problems we fortunatly not that hard to solve. After taking the bike for a spin to heat up the engine, I touched the exhaust pipes to see if they were hot. It turned out that cylinder 1's pipe was cold. So we've got our suspect. Apperently, cyl1 wasn't firing. To be able to fire, a cylinder needs a combustible fuel mixture, spark and compression.

  • I checked spark by removing the plug, fitting a plug and checking. Worked
  • I checked fuel by listening to the injector with a screwdriver. Injector fires

At this point, 3 possible causes remaining.

  • Sparkplug defective
  • No combustible mixture due to injector flow problems
  • No compression

So, the following was done

  • Got injector cleaner and applied it to the fuel
  • Replaced sparkplug. Upon replacing, I noticed the plug wasn't fit properly

These steps seemed to have solved the problem cyl1 was having

The RPM problem turned out to be a controller malfunction. When the RPM's went above a certain point, the software showed that the controller counted 34 teeth and 1 gap, where it should have counted 35 teeth and one gap. So somehow, the controller was rejecting a valid tooth as noise. After fiddeling with some potmeters, it was suggested to replace a cap with a cap with a lower value. This makes total sense, as the cap was acting as a low-pass filter, and using a lower value would increase the cut-off frequency. So, big one out, small one in, tadaaa no more RPM problems!

Broken joint

After adjusting the valve clearances and mounting the tank again, I went for a little test drive. I may have slackened one valve a bit too much, as there is a new tickey sound, but it should be within spec. On this test-drive, a noticed that the bike was losing power at random points. With my newfound experience, I diagnosed it as an ignition problem. So, after some road-side inspection and wiggling of wires, it turns out that one of the leads suppling the ignition coils was being held together with the wire wrap rather than the actual solder joint, causing the intermittend power loss. I pulled the lead away, resulting in a slow ride home. Fixed the problem with a crown rock, and good as new


Throttle bodies

  • Remove throttle body assembly
  • Inspect throttle body assembly for signs of leakage and/or sludge
  • Disassemble trottle body assembly
  • Thorougly clean Tbodies
  • Make sure all throttle valves close properly and form a tight seal, creating a vacuum on engine start
  • Assemble Tbody assy

Fuel tank

  • Order rust remover
  • Order tank sealant
  • Purchase new external fuel filter
  • Remove fuel tank
  • Drain fuel
  • Remove fuel pump
  • Clean in-tank fuel filter
  • Clean tank
  • Apply rust remover
  • Apply tank sealant
  • Inspect hardening of sealant
  • Reassemble fuel tank


  • Purchase 4l 10-W40 engine oil
  • Purchase new oil filter
  • Drain oil
  • Remove old filter
  • Mount new filter<s/>
  • <s>Add new oil

Putting it back together

  • Arrange for syncrometer
  • Mount Tbody assembly (need blow torch)
  • Mount fuel tank
  • Setup test-run
  • Synchronise throttle valves
  • Adjust valve play
  • Arrange appointment with tuner
  • Take bike to tuner
  • Have the bike tuned
  • Have bike tuned again

Project management

  • Add more pics
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