Little EVO fun today14 Dec, 2017 in Head Hoggers tagged harlay head porting / harley 4 valve porting / harley big inch kits / harley engine building / harley engine performance / harley HP / harley machine shop / harley machining / harley service and parts / Head Hoggers / motorcyle mobile tuning by headhoggers Doing some EVO building today. Had to fix the case stud holes. Do not use serts or Coils to fix case stud holes! Does not work at all. We use a special lock and stitch insert with a jig to install. Check out the pictures below.