Wiring harness. Making one from scratch sucks. Especially with a FI bike. The variety of sensors and the fact that I got some from a UK supplier made getting all the crimp terminals, housings, strain reliefs, backshells, etc, a real PITA. The first go of the harness was a bit of a mess but it worked. I was lucky enough to know Peter H., great all around guy and owner of a Dynojet dyno! The initial runs on the bike were done at his old shop in Brooklyn, only 5 miles but nearly a 1hr drive away!
There was definitely a learning curve to getting it running right. To minimize electrical interference I needed to have have a custom PCB made to control the various relays and fuses needed for the ECU, fuel pump, fan, O2 sensor, coils, and water pump. We also load tested all the components so that I could be sure that each circuit was properly fused and the low output race alternator would suffice to run the system. The sparx generator we initially used did not last long as the rotor uneventfully threw itself apart due to excessive high rpm usage. I then switched to an expensive Ducati race part which worked with no problems.
Once I got a couple of minor gremlins corrected, and an ignition and a basic fuel map going we immediately were making nearly what the old engine was. Even more encouraging was the fact that I had reduced displacement significantly from the previous engine from 640cc to 560cc so our overall thermal efficiency had increased significantly, not unexpected due to switching from air to water cooling.
To get the engine to respond smoothly we had to make an airbox to keep the injector in still air. It made a big improvement on how the bike responded on the track. You can see a quick video of the injector here: http://www.youtube.com/watch?v=qZ2HfKN9KRM
Unfortunately, I was in uncharted territory on several fronts. We were finally above the magic 64Hp! Like how they marked the unknown on old maps, 'here be dragons' I was soon to be deep in 'here be broken parts' waters. Now with the airbox and a decent fuel map we were getting 72-73 Hp at the rear wheel, a great improvement. It produced noticeably faster laptimes and higher top speeds. There was one major problem, the engine had a very short fuse. We rarely had a trouble free weekend and the procedure was usually as follows: take it easy on a Friday practice, have the engine break on Saturday, spend all Saturday night fixing the engine, then winning our Sunday race. Helicoil stud holes, straighten bent valves after a belt breakage, replace yet another $160 head gasket. Once I used copper flashing from Home Depot to make a temporary head gasket! It worked and Todd won. In fact, that gasket may still be in the engine!
Sometimes we had problems that could not be fixed at the track. Todd was not having too much fun as a rider wants to ride, not watch the mechanics pull the engine yet again. I think it was the year that Todd spent a lot of time at the track but very little time actually riding. It was a tough time, the engine failures were expensive to fix and morale was relatively low. But we didn't quit and soldiered on. Todd was amazing in that even with the worst engine failures he never crashed or dropped the bike, a fact I was continually impressed by and gratified for!
We reached an upper limit of about 78Hp before we started pulling the top off the crankcases! It was not the end of the world as we could only get 78Hp in a test configuration with the gas tank removed. Since the chassis was originally designed for a horizontal inlet carburator there was not enough room for a downdraft throttle body to breathe. Chalk that up for the next revision.
Gotta run for now, will continue soon.