Drill and tap the aluminum dowel to remove with slide hammer. Heat block and support flange then drive out the tappet block. Spraying it with electronic freeze helps. Replace O-ring 70-6560, chill tappet block and drive back in whilst supporting flange. Dowels are 70-9465. Tappet block I measured is 1.157" but it does not have the O-ring groove so presumably 1.0625"? #023 O-ring 1.051" I.D., 1.191" O.D.
And when reassembling the push rod tubes, do you use all the stock paper washers and white seals, or is there a better parts list or procedure to follow ? I've done maybe ten 3-cylinder top ends in recent history, but they've all been T150's. This R3 leans forward and may put undue emphasis on the exhaust tube seals.
I use my adjustable pushrod tubes.I do not use a gasket at the cylinder base or rockerbox, just Gasket Eliminator, so that changes the the rocker angle slightly. Plus, depending upon the seat grind I might have to skim the valve tips to get the adjuster movement correct. I prefer not to raise the rockerbox because it adds another joint to seal. Everything is bolted down so the tilt of the R3 cylinders is not a factor in sealing the pushrod tubes. The head steady probably puts more stress in the cylinders due to frame flex than the weight of the top end.
Thanks for the info and part numbers. We saw the blocks, o-rings and pins listed in the 1974 X75 parts manual that were not shown in the 1970 R3 manual. ...But then we also noted that the tappet block oil delivery tubes were NOT used on later models.
We are now considering simply blocking off the flow of oil to the tappet blocks... which is a far less expensive way to keep the tappet block from leaking. What do you think of this idea ?
Tridentman / John - Thank you for that information. That's going to go a long way to making this bike better. And this is rather mandatory because Semper Gumby rides the heck out of this thing. Atlanta to Boston and return already this year !
So what is the advised method of blocking ? Did the Service Bulletin suggest a method ? Was there a special part ? Left to my own devices, I would remove the cap, and drill a hole about 3/8" deep from the inside to accept a tight-fitting ball bearing that is bigger than the stock oil gallery. In this way the bearing is trapped forever and can never work loose. Then I would stake the 4 holes closed in the cylinder base.
If I remember the factory recommendation correctly it was very crude---involving cutting the pipes and crimping the ends. Your suggestion IMHO would work fine and is certainly much more elegant! Best of luck!
So I went back into the R3 top end today and got it all fixed up in a 9 hour marathon job. The oil lines, due to thread locker on the retaining screw, were a bear to get out. Once the screws were out things went according to plan. The main bearing cap is quite beefy in this location with plenty of room to drill. The cap ended up being drilled using 15/64 and 1/4 inch, then the burr pushed up by drilling was removed. After that a clutch roller from a twin was tapped into place with some LocTite for good measure. Then the cap was cleaned and torqued back into place with the same bearing insert as before. There was no noticeable wear on the insert !