Needs Replacement?

[luckyd20]

So i was working on replacing my Push Rod seals and I noticed:



If you see in the right side mid pic the hole is slightly deformed. Nothing is loose but would this be something to be concerned about?

Also since I have the cylinder head off, should I clean the piston and the cylinder head from the black build up?

[Session101]

how are you going to clean the piston? i would also hone out the cylinder and replace the rings right? i would want that piston nice and shiny. are you doing a top end rebuild? i need to do that over winter

[Barry]

If you see in the right side mid pic the hole is slightly deformed. Nothing is loose but would this be something to be concerned about?

If you mean the pushrod hole I can't see from the picture what might be wrong with it. The pushrod tube should be a moderately tight press fit otherwise it will leak.

If you mean the hole on the far right with the obvious damage, one of the 2 side securing studs on the valve cover passes through that hole to be fastened on the other side by a nut and wavy washer. Can't imagine how it got damaged like that as those nuts should be barely more than finger tight. Maybe it was dropped and the valve cover took the force and transferred it through the stud to the head. As long as it doesn't leak oil I wouldn't worry about it.
  

[Bob_Roller]

What year bike do you have ?

Starting with the '81 model year bikes, the cylinders are plated, it's called Nikasil, it's like a nickel or chrome plate .

Don't hone it out, you'll ruin the cylinder, if you have the plating .

You can clean the cylinder head and piston top if you like, it's not going to make any real difference if you do or don't .

[nhmaf]

+1 with Bob R.

A hint to our newer members - it can be very helpful to us if you put your bike(s) including model year in your signature, so that we can refer to that when dispensing information to ensure we are talking about the right stuff.   The R65 twinshock-framed bikes shared alot of newer technology over their ~7 year run than the other airheads, but they still had changes over the years, including the switch from iron cylinder liners to Nikasil plated cylinders for the 1981 model year.

As to the damaged stud hole - I'm with Barry on the diagnosis - it may be possible to use JBWeld to repair the stud hole and replace the stud - it doesn't have to withstand a large amount of pressure in the valve cover.  A machine shop could probably aluminum weld in that spot and re-tap the hole for you, but it would cost more $$.

[luckyd20]

Thanks everyone! There wasn't any leak noted so I guess I won't worry about it.

I'm not doing a top end rebuild just needing to replace the push rod seals.

[luckyd20]

BTW, Can you point me to the correct torque values? My Clymers manual is difficult to find out.

[Barry]

Official torque settings for the 79 cylinder head nuts is a 3 stage tightening sequence 11lbft, 25lbft, and finally 29 lbft.  But nobody uses these figures for fear of pulling a stud out of the crankcase. 25lbft is the maximum you should use and some use only 23lbft. Adjust the 3 stages accordingly.

Official torque settings for the valve cover are also to be ignored or you will risk pulling the studs. Just beyond finger tight is enough. Few people would have a torque wrench that goes low enough with accuracy but to put a figure on it - not more than 4 lbft.  If the joints are good it  won't leak or fall off with this torque setting.

[montmil]

IIRC, the common thought regarding torque values on the cylinder studs is to avoid over-doing it and pulling a stud from the crankcase. Expensive. 23-25 ft/lbs is the most I'd use. Follow the tightening sequence shown in the manuals.

If you're planning on scraping carbon build up on the piston crown, be advised some of that grit can easily slip down the cylinder and reach the ring lands. That would not be a good thing.

Some folks pull the head and cylinder as a unit. When the piston wrist pin becomes exposed, draw it out and then remove the head/jug leaving the rings in the cylinder barrel. Base O-ring can be fitted over the connecting rod. The two small O-rings can be held in place with a dab of grease during reassembly. A very thin smear of YamaBond on the base is needed. Avoid using too much and keep the stuff away from the upper studs as they are oil passages to the valve train. Danger, Will Robinson!

[luckyd20]

Perfect thanks! I want to get this bike back together and start riding again