I would put non ferrous bits in the tank , but I doubt you will dislodge all the rust. Not sure what good the oxalic acid will do? I have a 18 month since last run Blade engine. I took plugs out, sprayed 3in1 in , left 24hrs, turned engine over with nut on end of crank about 4 times. Spayed more 3in1 or WD40 in, left 24 hrs, turned over by hand again and resprayed. Left 24 hrs then spun engine with starter motor, plugs out, more 3in1, 24hrs, more spinning. Plugs back in and I fired it up. If that engine is an air cooled TSCC engine, I have stripped and rebuilt them a few times! http://i145.photobucket.com/albums/r240/megawattblade/My%20Bike%20pix/File0004-1.jpg