Saturday 13 April 2013


A bit late updating this but I am delighted to announce I have ignition!!!

I got my transistors in the post a while back so I built the coil driver module and had a crack at starting the bike. At first I was getting a whole pile of nothing, then a few backfires and then a dead battery. I figured I must have had the wrong cylinders at TDC when I calculated the base advance angle so I went back 180 degrees and tried again the next day. It seemed to be making an attempt at starting but couldnt quite get there.

Coil driver module temporarily plugged into the old CDI plug.

So I went back to the drawing board and discovered that a bit of ambiguity around the language for calculating base advance in the manual had made me measure the angle the wrong way around. I took a stab at an estimated angle and it fired up first time! I had set the advance to be fixed at 20 degrees BTDC so I checked with the timing light and found it was actually firing at 1 degree BTDC. It just took a moment to redefine the base advance less 19 degrees within the ECU and everything lined up perfectly after checking again with the timing light.

Testing in progress

I had purchased a Bluefox race ignition unit for the mc22 a while back and had one of the guys on the forum map the ignition advance from it. Thanks to him, I was able to load in the Bluefox ignition map straight into the microsquirt table. The map is only 2D but it serves as a good base point until I get the fuelling sorted and then I can play with modifying it into a 3D map. The bluefox map is running with no issues now. I intend to ride the bike to test it out, make sure there are no signal dropouts or misfires at higher rpm and do some preliminary data logging but there are a few wires to tidy up first! Unfortunately, I have been travelling quite a bit lately so I've been behind on this project.

Screenshot of the ECU running the Bluefox map. The only gauges working correctly here are RPM, Ign advance & MAP

While running the bike on the Microsquirt ECU, I tried plugging the TachOut wire into the stock tachometer but the signal is clearly different. So rather than messing with the signal to get it to work, I used it as an excuse to pick up a Koso RX2N digital gauge! The installation of that will come at a later date.

Also, while browsing eBay one day, I happened across a set of CBR600RR ignition coils and harness for nice and cheap so I purchased. These are coil-on-plug so should tidy the engine area up quite nicely. Another advantage of the COPs is the lack of HT leads should minimise ignition "noise" in other signals going to the ECU. The wiring harness for the coils needed to be modified to allow for wasted spark firing. The coils should be installed shortly and I will update how they go.


Jzkk said...

Just wondering if i could use your ignition and fuel map as a base for my cb250f efi project??

motthomas said...

Hi! I would be able to give you the maps but I would advise caution in using them for your engine. Its the hornet 250 right? As far as I know, the hornet does not rev as high as the mc22 and has more mid-range power achieved through different cam timing. That would throw the VE curve off from the mc22 engine and consequently the ignition and fuel maps. I can give you copies of the maps but only as a base to use for proper tuning to your specific engine.