Just installed a pair of zerks for the head bearings today. I think just one would have done it if I would of put it about another Inch up from the bottom.
Gave her about 30/40 pumps and grease, came out top and bottom. Drilled one small hole first then the correct bit for the 1/4-28 thread. Vacuumed out the hole instead of blowing it out even though the particles are pretty small.
Don't see why it wont work? Sure does beat tearing down the front end for a little grease. I probably will never have to grease it again.

 

Is that on a 1917 Yamaha or what?

 

Looks good. I plan on plan input to g a fitting in mine.

 

 

Possible mess but no different than on the later models that had zerks.
Little soap and water will take care of it.

 

If you use the right type of grease there will be no mess. I used the Lucas red stuff it never run

 

Considering the service manual puts servicing the bearings at 50k, I would prefer to have the bearings inspected. Had to replace mine at 100k.

 

Warranty concerns with frame integrity compromised comes to mind.

 

I would not worry much about weakening the tubing with two quarter inch holes filled with zerks. The welded tubes to the neck tube with break first.

 

Always a good idea to give grease to those bearings.