'77 R100/7 Head Torque

[RICHO2006]

I need to replace the push rod seals on a '77 r100/7. Can anyone help me with proper torque for the head nuts?


Thanks

Richard
Commerce, Michigan

[20774]

Everyone's afraid of anything to do with pushrod tubes lately. :ha

I think the spec is 26-29 ft-lbs, but most will say not to exceed 26. I'd shoot for 24-25 or so and call it good. Torque should be in a criss-cross pattern and in stages, maybe taking 3 stages to get up to the final value.

Kurt in S.A.

[flash412]

If you replace the head gaskets. After one good heat-cycle, retorque the heads and re-adjust the valves. Then you're good to go 'til the next service interval.

[robsryder]

I needed to replace the leaking left side pushrod seals on my R100GS/PD recently.

Here is what I did :
0) Remove carb and exhaust header from left hand side (LHS) of engine.
1) Remove plugs from both cylinders.
2) Remove valve cover from LHS - note a bit of oil will drip out
3) Remove rubber plug from "timing" hole on left side of engine, just aft of the engine oil fill port.
4) Place transmission in 5th gear
5) Rotate rear tire while viewing timing hole (flashlight helps!)
6) When at top-dead-center (TDC) shown as OT, check that the LHS valve rockers have some movement (same as though one were going to check / adjust valve clearances). If the rockers are tight, then rotate rear wheel so that engine turns over one revolution and you are back to OT. Check for rocker movement. If rockers are still tight, then either remove right-hand-side valve cover and check for rocker movement or carefully observe valve motion when rotating rear tire - the objective is to be at TDC on the compression stroke.
7) When at TDC loosen each of the six head bolts in a criss-cross pattern 1/4 turn (90 degrees - or if viewing a non-digital clock face, from 3 o'clock to 12 o'clock).
8) You can save some money by keeping the head and cylinder connected together - do not loosen the top and bottom nuts any further.
9) Loosen and remove the four head nuts holding the valve rockers in place.
10) Prior to removing the rocker, I like to loosen the locknut and adjuster - it may be best to do this prior to removing the nuts from the cylinder studs.
11) Carefully remove each rocker assembly - maintain the relative orientation of the components. Some have suggested use of a "twist-tie" to keep things together. I prefer to carefully set the rocker assembly in a small plastic tray and set the tray inside a plastic bag. Don't confuse the inlet and exhaust rockers with one another!
12) Withdraw the pushrods. I like to maintain the pushrod orientation (so that the end that was in the engine goes back into the engine). Don't confuse the inlet and exhaust pushrods with one another!
13) Gently begin withdrawing the head/cylinder assembly outward. Do not let the piston completely come out of the bottom of the cylinder. Some rocking motion may be required to allow the pushrode seals to become unseated.
14) When the piston pin (connects the piston to the rod) is visible, but before the rings have emerged, stop withdrawing the head/cylinder from the engine.
15) Remove the circlip or ring that secures the pin in the piston. The ring is most easily slipped out using a small screwdriver or other similar object and prying with the little opening. [This step really needs a photo illustration, particularly for reinstalllation of the ring {new ring recommended}]
16) Once the circlip or ring is removed, withdraw the pin from the piston sufficiently to allow the piston to become free from the rod. No need to fully remove the pin. Note: on my GS/PD the pin was easy to remove. On my /7 RS I had to heat the piston with a heat gun and gently tap the pin out. A special tool is available for withdrawing the pin, but some heat may still be needed.
17) Once the piston is decoupled from the rod, the head/cylinder (with piston still partially stuck in the cylinder) may be fully withdrawn from the cylinder studs. I use a rubber band about two of the cylinder studs to keep the rod from striking the engine case. Be careful and do not let the rod fall and ding the soft aluminum engine case!
18) Remove the old pushrod seals.
19) Install new pushrod seals onto pushrod tubes. The "lines" should be oriented downward when the cylinder is in its proper orientation. I use a bit of silicone lubricant on the rubber seal to help it onto the tube. I put just a bit on the part of the seal that will go into the engine.
20) There were some small O-rings on the top studs on both my GS/PD and /7 RS. These O-rings were renewed.
21) The GS/PD was shown as having an O-ring about the base of the cylinder, but mine did not have one from the factory! There was a slot where such an O-ring would seat. I placed a new O-ring at the base of the cylinder. The /7 RS did not have an O-ring at the base of the cylinder.
22) Clean the area where the engine case and cylinder (and pushrod seals) meet. I use a kerosene wetted rag and a small bit of ScotchBrite. Carefull with the ScotchBrite as it is undesireable to get either the debris removed or aluminum oxide embedded in the ScotchBrite pad into the engine.
23) While accessable it may be desirable to withdraw the pushrod lifters and inspect - use of a magnet is not recommended as it may slightly magnetize the lifters thereby attacting small ferritic fines which could damage the engine. Mileage and other conditions may dictate the desirability of this inspection step.
24) Apply a very thin coat of hylomar about the base of the cylinder and engine case (where it meets the cylinder). I also put a thin coat of hylomar about the pushrod seal holes.
25) Replace the head/cylinder onto the cylinder studs.
26) Fit rod into cylinder. Aligh and push pin into place. This always seems to take me a bit of time. If it took heat to get the pin out, it will likely require heat to get the pin back in place. Use of the special tool is recommended over tapping the pin. It is really, really undesireable to bend the rod while banging the pin into place! For my GS/PD the pin easily slid into place once the hole in the rod and piston were lined up.
27) Replace the ring or circlip securing the pin in the piston. The circlip was easy. The first time I tried doing the ring replacement it took me 2 hours and 3 rings. Two of the rings are still somewhere in my garage, where they flew I know not! Subsequent efforts went a bit easier. You have been forewarned!
28) Continue pushing head/cylinder into place.
29) Check that the pushrod seals are beginning to go into their holes. You did replace the pushrod lifters if removed, didn't you?
30) I usually can't get the pushrod seals to seat fully just by pushing by hand. Once the head / cylinder is mostly in place, I re-insert the pushrods, then carefully replace each rocker assembly in place - everything should be in the same orientation as when removed.
31) Replace the four head nuts on the studs and hand tighten.
32) Use a torque wrench and tighten each of the six head nuts in a criss-cross pattern to 8 ft-lbs. While tightening the nuts on the studs observe the seating of the pushrod seals and the cylinder to the engine case. I like to give each nut on the cylinder studs a quarter turn while observing everything seat. Carefully observe that the top of the pushrod is properly seated in the adjuster. Stop if something is hanging up. The end of the pushrod may not be fully in the lifter - a little movement of the pushrod should help it slip into place if not already so.
33) For my /6 bike I use a large C-clamp and sockets to keep the rocker end float to a minimum. [A photo would really help illustrate this better than I can describe.]
34) Torque each of the six head nuts to 16 ft-lbs in a criss-cross pattern.
35) Torpue each of the six head nuts to 26 ft-lbs in a criss-cross pattern. It is assumed that one has an appropriate torque wrench, that is working properly within the 20 to 80 percent range.
36) Adjust intake and exhaust valves to proper setting.
37) Rotate rear tire so that engine undergoes two revolutions. The LHS valve rockers should be able to be moved. Re-check valve clearances, adjust if necessary- and re-check.
38) Replace valve cover, spark plugs, rubber plug in timing hole, carburetor, and exhaust header.
39) Check cables to carb to ensure that they are properly seated.
40) Start bike, check for leaks. If no leaks go for ride, get the bike warmed up.
41) Upon return from warm-up ride, resynch carbs.

This procedure was generated from my recollection as I sit at the keyboard. Users are encouraged to consult their manuals and/or other resources (e.g., Snowbum's website, Oak's Top End manual, etc.)

[RICHO2006]

Thanks for all the information.



Richard

Commerce Michgan

[pmdave]

Just wondering here...are you attempting some engine work without a shop manual? (you know, where all the torques are listed, and they have lots and lots of neat photos showing exactly how to put it all together again)

pmdave