So i've read alot about the rough idle that occurs in the heat while sitting in traffic on the f4. Stalling, hard to start, and runs like crap when hot and not moving seems to sum it up. The gist of it all seems to be a week spark at the coils as i've seen most guys just put a jumper wire between the battery and fuel pump transfer relay and bingo...no more running issues. But no one seems to have taken it any further than replacing stock parts or putting in the jumper wire. This black/white wire powers a lot of items like the coils, fan, fuel pump, and all of the relays. All that stuff on an 18ga. power wire makes no sense to me at all. It seems to me that the coils should have a relay and straight battery power with nothing else connected to them to interrupt the spark. I already removed the fan from the black/white loop and installed a manual switch for it. Now i'm going to install a bosch 30 amp relay between the coils and the black/white wire, powered straight from the batterry, turned on by the black/white wire leading to the coils. I'm going to rewire the coil harness with some nice 12ga. wire and plug it all back in. Just as a side note, this was a very common mod on older bikes with the two large coils. Always worked a charm too. Thoughts?

 

Part of the issue is that the standard honda Reg/Rec does not really charge at idle so you are running on the battery only. ( the worse condition your battery is in the worse the bike runs )

The blackbird seems to have the same lumpy idle when hot and sitting in traffic.
I changed the reg/rec on my blackbird to an FH012AA mosfet reg/rec from a Yamaha R1.
( the replacement is the new FH020AA )

Bike now charges from idle to redline and the hot running is also cured.