The Grey Ghost Restoration-Part 3 Engine

First, a quick update on the frame straightening.  I got the Ghost back in December after dropping it off on Halloween.   I was in South Africa most of November.  As the fork tubes were bent and on back order, it took a few more weeks to get them and complete the front end work.  Replaced parts included the upper and lower triple clamps, but fortunately, I secured a used lower clamp at $250 which was a good savings over the $460 retail. 

Today, my youngest son, Branden, came over and he took apart the the top end with some instructions from me.  I’ll take the parts over to BMW of Denver so Clem can check them out.  I suspect the valve seats will need replacing and the valves lapped.   I’ll also install new ring sets. 

Here’s the sequence of steps Branden followed to take apart the top end.

Remove Carbs & Plugs

This is pretty straight forward.  Removing the cables and the air tubes securing the carbs is simple.   Remove the air tubes then detach the throttle and choke cables from the body.  Branden is holding the carberator showing where the throttle and choke cables attach to on the back side of the carberator.

Carb removed 

When Branden pulled the plugs, it was clear the right side (top plug in the picture) was running pretty lean.  We’ll be doing a carb rebuild and will balance the carbs when we reassemble the bike.  I tagged the plugs with the side they came from so I can keep track of things like this.

Plugs - Top is Right, too lean 

As Branden removed parts, we put the parts we are keeping in the garage in one box, and the parts to take to BMW of Denver in a second box.  It’s good to label parts for which side they were on and take pictures during disassembly.  You don’t know how long it will be before you put things back together and you will forget small details.  Labels and pictures save a lot of time and mistakes.

Parts box 

Here’s the bike when Branden got the carbs and plumbing removed.

Carberator and pipes removed

Remove Exhaust 

We used the BMW supplied wrench to remove the exhaust nuts securing the headers to the heads.  Since these nuts are cast aluminum, banging on them with a mallet is a great way to break them.  The wrench ensures this won’t happen.  Be careful fitting it to the nut and make sure its inserted all the way or you can break a fin on the nut. You can use a cheater tube on the end of the wrench to get them loose, or you can use a mallet on the wrench handle to get the nuts to loosen up.  Then, you can spin them off by hand.  Branden used the mallet.

Exhaust pipe nut wrench 

Next Branden removed the bolts securing the muffler to the right exhaust hanger.  I had installed an after market Lueftmeister 2 into 1 exhaust back in 1980.  You have to remove the pipes from the right and left hangers if you have the standard exhaust.  I’ll be installing the stock muffler and exhaust pipes on this rebuild.  The Lueftmeister has a crack. so I’ll like scrape it or sell the headers on Ebay.

Bolts securing exhast

There are steel rings inside the exhaust nut that seal the exhaust pipe to the head.  These nest into each other to create a seal preventing exhaust gas from blowing by the exhaust pipe.  The outer ring is solid with a square profile and curved inside radius.  The other ring is split and has a beveled profile.  These fit together as shown. I taped them together the way they are assembled so we won’t have to think about how they go together when we reassemble the exhaust.

Exhaust head nut and seal reing Exhaust pipe seal rings 

Here’s the bike with carberator and exhaust plumbing removed.  We found we had to also remove the rear brake peddle to allow Branden to remove the exhaust.

Exhaust off the bike 

Remove Valve Covers

There is a chrome nut in the center of the cover and also two small nuts behind the valve cover near the intake and exhaust pipes.   You can see the stud on the cover here.

Back side of valve cover-stud w/ nut 

It’s a good idea to put a pan under the cover as oil will drip out from the bottom of the valve covers when they are removed.  You can see the oil stream as Branden pulls the cover off.

Pulling valve cover loose 

Remove Cylinder Heads

The cylinder studs extend through the head and are used to secure the rocker arm assemble of the valve train.  These are torqued in a cross-wise pattern, so I like to loosen them in a cross-wise pattern and then remove them.

Removing rocker arm nuts - cross pattern Removing rocker arm nuts - cross pattern 

The rocker arm assembly has two square steel blocks, pillow blocks, on top and bottom of the rocker arm assembly.  There is also a shaft that the rocker arm rotates on.  Inside the rocker arm are needle bearings.  Branden has his thumb on the rocker arm. The pillow blocks are visible with the slot cut through one side and the shaft the rocker arm rotates on can be seen at the center of the pillow blocks.  The nuts on the cylinder head studs have been loosened.

 Rocker nuts loosened 

To avoid dropping various parts, its a good idea to pinch the pillow blocks as you slide the rocker assemble off the cylinder head studs.  Branden is squeezing the pillow blocks together as he slides it off the cylinder studs. 

Pulling rocker arm assembly off 

Next Branden pulled the push rod out and labeled the parts showing the side, and if the rocker was the intake or the exhaust so we can assemble them correctly. Note that my push rods are not the standard steel ones.  They are titanium racing rods.  See Part 1 about how those got there 🙂

Rocker arm with pillow blocks & Push Rod 

Branden then removed the nut that is above the spark plug hole.  There is a second one on the bottom of the cylinder head directly beneath the top one.   Although I haven’t dropped one into the spark plug hole, be cautious when removing it.  If you do drop it inside the engine, no worries because in another minute, the heads come off anyway so you can retrieve the nut.

Top nut securing head 

It’s time to remove the heads.  There is a head gasket and sometimes the head does not want to slide back right away.  Working it back and forth will loosen it enough for it to slide back.  Be careful you don’t pull too hard, or when it comes loose, you can end up on your butt or drop the head.  Be patient.  It took Branden a couple of wiggles to get it loose.

Pull head off 

Remove Cylinders

I like to position the pistons at top dead center before removing the cylinders.  This leaves the connecting rod extended as you pull the cylinder back.  I don’t want the rod to fall onto the engine case when the piston comes out of the cylinder, so once enough of the connecting rod is exposed, I stuff some shop rags between the connecting rod and the engine housing to support it.  The base gasket can also be a bit stubborn, so you may have to rock the cylinder a bit to break it loose.  Branden didn’t have that problem on either cylinder.

Head off, piston fully extented Rags supporting connecting rod

Gently pull the cylinder back and catch the piston with one hand and gently let it rest on the cylinder studs.  It is a good idea to wrap it in some shop rags so you don’t harm the rings.  We’re going to replace them, so we didn’t worry about that. 

Head off some cross hatching still visible 

Once the cylinder is off, you can remove the head gasket.

Head gasket & piston 

And you can remove the push rod tube boots.  I knew they were leaking, so likely they were split.  As you can see, that’s the case.

Push-rod tube seals - cracked 

Remove Pistons

To remove the pistons, there is a C-clip on each side of the wrist pin that has to be removed.  There is a slot at the top of the wrist pin hole in the piston.  Use an awl in the slot to pry the C-clip loose. 

C-clip removed - note recess 

Branden is using the awl to pry one of the C-clips loose.

Awl in recess removing C-clip 

Now, we have to remove the wrist pin.  You need a drift to help tap the pin out.  I use an appropriate sized socket with an extension as the drift.  Be careful that the diameter isn’t too large or too small.  The socket should rest on the shoulder of the wrist pin.  Use a rubber/plastic mallet and tap gently increasing the force a bit until the pin starts to slide out the other side.  The mallet ensures you don’t ding the piston or rings should you miss hitting the drift.

Using drift to remove wrist pin Wrist pin coming out 

We labeled the pistons and wrist pins so we know which is from the right and left cylinders.  Here’s a picture of the pistons, wrist pins and tools used to remove the wrist pin.

Pistons, wrist pins, tools 

We completed the top end disassembly in about 2 and 1/2 hours working at a leisurely pace. 

Here’s the heads and cylinders after removal.

Cylinder and head removed Cylinder and head removed 

Next week, I’ll take the box of top end parts to Clem at BMW of Denver to inspect them and we’ll see what needs to be worked on or replaced.  In the meantime, I’ll be looking for more parts on eBay, inspecting the stock exhaust that I had stashed back in 1980 when I put the Luftmeister 2 into 1 on to see if I need to replace some of the components.  I also am on the hunt for a good local motorcycle paint shop.  I’ve finalized the color to be R90/S smoke silver similar to what is on the Ghost now.  However, that paint job was not done correctly, so I’ll be looking to get this one right.

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