Thought I'd resurrect this thread with some info on fitting a Keihin FCR39 to my EC400.
Bike has sat, and refused to start for nearly two years. I've had the head rebuilt, got spark and compression, and injector tested fine when connected to 12 volts. Bike just refused to start.
A couple of weeks ago, I got fed up, and connected an FCR39 carb I had in the shed to the bike. Hit the button, and she roared into life!
Not only that, but the bike went a lot harder with the FCR than the EFI, so I decided to make it permanent.
Fitting the FCR was a bit tricky, I actually had to remove the left upper rear shock support. If need be, I can reinforce it later.
The shock fits in pretty snugly.