Base O'ring check, change and precautions (PIC)

[mfrias2nd]

My 82 R65 had about 35k miles on it when I purchased it and it has been a project in the works since. It runs great but i noticed this wet base. Common sense tells me to change the o'ring, and gasket as it looks likes it's wet all around not just in one corner. However, I've never gone into this work on this machine, I know my way around engines and a tool box so I'm not worried and the instructions i've found are simple enough. Does anyone care to give me pointers? things to be careful with, precautions to take or tips? Or will should I try to retorque the head bolts first?

[Bob_Roller]

Your first problem spot, may be removing the finned nuts holding the exhaust pipe into the head .

If they have not been removed and had anti-seize compound applied to the threads before, you may need to cut the nuts off, or risk damaging the soft aluminum threads on the head .

[mfrias2nd]

Ok Ok this is a good precaution. haha...i hope that doesn't happen. I figured the right side dried out because it was stored on it's side stand for god knows how long.

[nhmaf]

Yes, the exhaust nut thread item is a good thing to be aware of - it can spoil your whole day.   Do you have the special exhaust nut wrench?  

I suppose that I would at least check the torque on the headbolts first - if they seemed low (under 20 ft-lb) then I'd carefully retorque them in criss-cross/diagonal pattern bringing them all first up to ~12-15 lbs, then 20, then stopping just under 25.  DO NOT GO OVER 25 or you will risk pulling a stud!!!

Of course, if you retorque the heads - you'll need to recheck the valve adjustments too.

BUT, if the nuts seem to be about the proper torque (23-25 ft-lbs), then I would start preparing for the job.   For each cylinder, you will need the large o-ring, and 2 small o-rings for the 2 studs that use them, and while you are there you may as well replace the pushrod tube seals so you'll need 2 of those.   You may or may not need a new valve cover gasket - if yours has been replaced in the past few years I wouldn't bother as long as it isn't damaged when removing the valve cover(s).     Also, you may want to just get a set of new head gaskets if you end up separating the cylinder from the head.  You will also need a tube of YamaBond or Hylomar to put a very thin schmear on to help seal things up again.

Alot of folks rotate the engine to TDC before removing the cylinder so that the piston can be left in the cylinder - you won't need to replace the rings that way.  There are tips on doing this step (removing circlip from wrist pin and drifting out wristpin from cylinder, leaving top of the piston inside the cylinder bore) are available in several places - including Oak's Top End Manual, which I have somewhere around here...

[mfrias2nd]

EXCELLENT TIPS. Also, I read that the later airheads had cone spacers which automatically spaced the rocker blocks accordingly. Can anyone verify this? I do not have the H Jig I've seen in other instructions.

[tvrla]

You can leave two of the head studs attached and remove the cylinder and head together. No need to replace the head gasket or fool around with it. I re-use head gaskets all the time, but I'll smear a light film of gasket sealer around the top two studs and the push-rod area - both sides of the gasket.

Oil to the rockers comes along the top two studs, so definitely keep the area around the top two studs clear! VERY IMPORTANT!  Only wipe a small amount of sealer all the way around the base of the cylinder - much easier than applying it to the block. Definitely apply a thin layer of sealer to the block/cylinder junction even though an o-ring is used. I never totally trust those o-rings. Apply some grease to the recesses in the head where the small o-rings go to help keep them in place on installation.