i have the cb550 k3 and found during the initial rebuild of the engine that the head had to be removed for one reason or another
so i ended up doing away with the pesky oil seals at each end of the head between that n the barrel.
i fitted a 7mm dowel to each side and the head fits snuggly onto the dowels n torqued down.
have done 150 miles so far and all is good,no leaks and cyclinders/plugs are dry,means you dont have to buy a full gasket set
any time the head comes off too.my next step is to cut off the studs that hold the inlet stubs on,drill and tap threads so that
the stubs can be fitted to the carbs before mounting them and 10mm bolts to hold them on instead of the painstaking task
of trying to feed a bank of carbs past the stubs and squashing the inlet rubbers,what a job that is!
