I use gun cleaner.  Hoppes 9 I think is what it is (I'll verify when I get home).

Open the bottle, drop in the injectors, slosh them around gently, and let it sit for 45 minutes or so.  They come out sparkly clean :)

Kevin
________________________________________
From: Lancair Mailing List [lml@lancaironline.net] On Behalf Of Paul Miller [pjdmiller@gmail.com]
Sent: Thursday, November 07, 2013 6:01 AM
To: lml@lancaironline.net
Subject: [LML] Injector cleaning

This is what I'm using to clean the injectors in the IO550.  So far, it is inexpensive and effective.  The $32 harborfreight ultrasonic cleaner is just fine for me.   It does have a short cycle which is OK for frequent inspections.  The finished product is clean outside and spotless inside.   The last photo shows the troublesome deposits on my injectors.  The shot is looking into the injector from the engine side of the nozzle so that's the area where the jet expands and exits into the intake manifold.  This #2 is still showing some black after an hour of repeated cycles in the bath.   These injectors were obviously quite dirty and overdue for cleaning.