I'm trying to trouble shoot hard start problem to no avail.
The bike when cranking sounds like the battery is flat: every single lamp dims, cranking RPM suddenly droops, it sounds like nyeh-nyeh-nyyyeeeeeeeaaaaah-[everything dims]-nyeh-nyyeeeeaaah-[everything dims]. Bolting another battery and extra ~80A 12V power supply in parallel doesn't really help.
*HOWEVER* if I disconnect the injectors the starter turns crazy fast, hooking injectors back and here we go, the engine suddenly becomes hard to start and sounds like the battery is flat.
It really looks like the ECU is sparking too fucking early? I had carbed bikes with non-CDI ignition and a kickstarter, fuck up ignition advance and you'll get precisely that, albeit the bike will kick you and launch you to the moon.
Background / what I've done so far:
I got the bike few years ago, it's a 2002 busa with 32bit ECU. I got it with full titanium exhaust and DNA air filter and semi-flat battery, I thought the hard starter issue is due to stock ECU and lean mixture topped with old battery. Replaced the battery with a new one (YT12A-BS) and got an OEM air filter. Doing all that slightly alleviated hard start issue but not that much.
I also got the bike with few thick ground wires bolted here and there from the negative battery terminal, removed all of them and was unable to start the bike since it was cranking sloooowly as hell. New battery cured that.
Ok what I did since then:
0. new spark plugs, sync'ed TB's and adjusted idle / TPS
1. Replaced started motor/starter clutch/starter motor covers. Got all that from the next gen motor.
2. New in-tank fuel pump, trying first the one from 350z and now I run AEM 320 one with dedicated relay/fuse/wires. External fuel filter. AEM fuel pressure regulator. Fuel pressure is rock steady.
3. Went full retard and replaced starter motor "+" and "-" wires with two 4 Ga in parallel for "+" terminal and one 2 Ga for negative. The wire from the "+" battery terminal to starter relay is now 4 Ga.
4. Adjusted valves, everything is within the spec. Compression test shows 14-16 bar across all cylinders.
5. Tried two different ECU's. Tried OEM flash.
Going to check crank shaft position sensor. If it checks OK what should I do next?