Wiring the coils directly to the battery through a relay on an RD400, where did you place the relay? I have a 350 y-boot with a K&N filter. It's pretty tight back there.
Looking for advice before going forward.
Thanks!
I ended up fitting it on one of the bolts of the rear brake piston mounting bracket I fabricated.
Voltage to the coils is good now and it runs much, much better. Still dialing the carbs and timing in as it runs great at 3/4 throttle, but not getting over about 75mph,stumbles a bit from a stop.
Many thanks to all who help out here!
only time ive dont that mod revently was on my kz. only 75? somethings def amisd
Quote from: m in sc on June 08, 2026, 04:46:25 PMonly time ive dont that mod revently was on my kz. only 75? somethings def amisd
Definitely. I do plan on tracing the voltage drop through the entire run. This was more or less a proof of concept to get to a real baseline. I was getting 9v at best at the coils prior to running through a relay from the battery.
yeah . thats def a problem
Keep in mind the RD400 has that ballast resistor ahead of the coils so voltage right at the coils is not going to be 12 volts.
Quote from: 1976RD400C on June 09, 2026, 06:00:20 AMKeep in mind the RD400 has that ballast resistor ahead of the coils so voltage right at the coils is not going to be 12 volts.
The ballast resistor has been bypassed. This was recommended by Economy when installing their replacement coils.
Quote from: ElFuegoBlanco on June 09, 2026, 06:31:16 AMQuote from: 1976RD400C on June 09, 2026, 06:00:20 AMKeep in mind the RD400 has that ballast resistor ahead of the coils so voltage right at the coils is not going to be 12 volts.
The ballast resistor has been bypassed. This was recommended by Economy when installing their replacement coils.
:thumbs: