I've been fighting a strange issue with an FCR39 that I've been attempting to fit to my '03 FE400. Well, after several attempts I'd all but given up for a while. The only thing I hadn't given a go was putting in an OEM fuel screw. Well, I had an OEM fuel screw in my container of jets-n-stuff. I installed it and all is well. So I had a look under a magnifier at the metering portion of each and the after market appears to be a bit thicker, so much so that some of the aluminum was scuffed from the FS orifice up near the pilot passage. :?