30 March 2003 - I decided to start engine disassembly. I removed
the cover over the magneto timing gear. I also removed the front cam gear
cover. On both the magneto gear and cam gear I noticed a mark on a tooth. When one mark was in the 6 o'clock position the other was also in the
same position. With the cam gear
cover plate off I could not see any mark on the crankshaft gear (the gear was
not easily visible when trying to view it). The photo below shows the cam gear.
The mark on the gear tooth is in the 6 o'clock position, but is not easily visible in this photo. If you look closely
at the case right below this tooth there is an arrow stamped in it (I am sure
this is to line everything up when installing the chain.
2 April 2003 - I found an arrow on the flywheel mark
"TDC" there is also a mark on the flywheel housing at the 6 o'clock position. The camshaft and magneto will make one
complete revolution for two revolutions of the crankshaft. If you line up the
TDC arrow on the flywheel with the mark on the engine case (the TDC arrow is
also at 6
o'clock). The marks on the
camshaft sprocket and magneto sprocket are at 6 o'clock. If you rotate the flywheel one complete revolution
(the TDC mark at 6 o'clock) the marks
on the camshaft sprocket and magneto sprocket are now at 12 o'clock.
I removed the magneto
chain by removing the clip on the link and then the link that holds the chain
on. Next I removed the screw on the top of the magneto-securing band and
removed the magneto.
3 April 2003 - I removed the covers to the valve adjustments.
This gave me access to the 12mm nuts that are located between the valve
tappets. This nut is one of 5 that secure each cylinder to the engine housing.
Next I removed the remaining 4 15mm shouldered nuts the secure each cylinder.
Once the nuts were removed the cylinders slid right off. A quick examination of
the cylinder sleeves showed nice shiny, well oiled sleeves with no scoring or
marks. Upon further examination it appears that the cylinders match and are
interchangeable from side to side. Each piston has three rings on it.
5 April 2003 - Today I debated whether to remove the clutch, remove the pistons or remove the crankshaft. After
removing the clips from one piston, I found that the pin that secures the
piston to the rods would need to be pressed out. So I decided to remove the
crank. The top of the engine case was secured to the lower case with 13 13mm
shouldered nuts and 13 shouldered washers. Once they were removed the top of
the engine case lifted right off. With the top of the engine case removed I was
able to remove the crankshaft. The rod bearings seem nice and tight. I am not
so sure about the front and rear crankshaft bearings.
6 April 2003 - I decided to go ahead and remove the clutch. 6
14mm nuts hold the clutch assembly in the flywheel. I removed every other bolt
(3) and replaced them with 8mm x 1.25mm (50mm long) bolts with a nut screwed
down to the top plate (see photo). Next I removed the remaining 3 bolts. I
slowly backed the nuts on the bolts I added to release the clutch assembly.
Once the clutch was removed I had access to the 38mm nut that secures the
flywheel to the crankshaft. There is a washer under this nut that is bent up on
two sides to secure the nut in place.
8 April 2003 - Today I removed the oil screen in the bottom of
the lower engine casing. This screen is right below the crankshaft. It was held
in place by 4 dome shaped screws with small holes in the heads. The screws were
safety wired into place with a single piece of safety wire that passes through
all 4-screw heads. I am in the process of trying to locate a 38mm impact socket
so that I can remove the flywheel from the crankshaft. I have spoken with
"Vech" from Bench Mark Works. He offers a
solution to replace the felt seal that is at the rear of the crankshaft,
between the flywheel and crankshaft. It replaces the felt seal with a modern
seal to eliminate oil leakage into the flywheel area. It requires no machining
of the engine case.
9
April 2003 - Removed the
10mm nuts and washers that secured the oil pump and filter cover to the lower
engine case. Removed the pump and filter. The filter
was an original style and the pump pumped oil through when the top shaft was
turned. The lower engine case is covered with hardened grease and oil. I am
going to scrap it off with a wooden dowel before putting the case in the parts
cleaner. I drained the remainder of the black molasses oil that was in the
engine case (probably from WW2).
13 April 2003 - An update, not much in the
disassembly area this weekend. I
started to clean the engine parts and sandblasting them (this will continue for
a while). Note: the $199.00 sandblast cabinet from Harbor Freight works great
(I am using a 60 gallon air compressor set at ~80psi with medium glass beads).
The photo below shows some clean parts next to dirty parts.
On one piston the oil scraper ring is
broken. I have been unable to locate a direct replacement with any of the repo parts vendors so far. Anyone?
22 April 2003 - Today I removed the camshaft. The first thing to
come out was the bolt on the right side of the engine housing that is safety
wired to the housing. This holds the camshaft in place (along with the press
fit of the front bearing housing). See the photo below.
Once the bolt was removed
I heated the engine case at the front and rear of the camshaft where I thought
the bearings might be. I tried to use a gear puller to extract the camshaft but
could not get it around the front gear. I decided to tap the camshaft out by
tapping on the back of the front bearing housing. I was able to tap it out but
the housing has some marks from the tool that I will need to smooth out. The
photo below shows the camshaft and the valve tappets. I removed the tappets
from the ends of the cam followers (they contact the cam lobes) thinking I
could then get the cam followers out of the engine housing. Wrong, apparently
the bushings that the cam followers are in need to be pressed out of the engine
housing in order to get enough clearance to remove the followers. I decided not
to remove them as they appear to be in good condition.
23 April 2003 - Cleaned off top engine case and camshaft with carb cleaner. I found an interesting stamp in the cast BMW
logo on the right side of the housing. There is an eagle with a swastika
stamped into the middle of the "W". It had a number underneath it
which was "4754" or "754".
24
April 2003 - Bead blasted
the upper engine case. Reinstalled the camshaft. I heated
the engine case up in the oven to 400F, stuck the camshaft in the freezer. The
camshaft dropped right into the upper housing. A couple of taps with the hammer
and the front bushing was in place for the camshaft locking bolt that passes
through the right side of the engine case to lock the camshaft in place. What a
nice clean engine!
25 April 2003 - Today I removed the pistons. I remove the four
clips that help hold in the piston wrist pins. I then heated up the pistons with
a torch. I then used a 12mm socket and tapped out each wrist pin. Next I
decided to remove the front bearing off of the crankshaft. I removed the front
gear with a gear puller and then removed the bearing with the puller. There is
an outer cover on the bearing that I need to figure out how to remove. Below is
a photo of the parts that come off of the front of the crankshaft in the order
they came off.
29 April 2003 - Today I removed the flywheel. I used a 1.5"
(38mm) impact socket along with an impact wrench to remove the rear crankshaft
nut. Next the washer came off. I used a large gear puller hooked into two of
the six holes in the flywheel to remove the flywheel from the crankshaft (along
with a couple of whacks from the hammer. Next I removed the woodruff key from
the crankshaft and then used a small gear puller to get the rear bearing and
carrier off of the camshaft. The photo below shows the rear bearing carrier
taken apart and the bearing removed. I am holding up the
splashguard portion of the carrier with what I believe to be the
"felt" seal in it (see circle). Vech of BenchMarkWorks offers and upgrade
that removes the felt seal and utilizes a modern seal in order to prevent oil
leakage from the rear of the crankshaft.
30
April 2003 - Tonight I
cleaned up the crankshaft. By applying radial pressure to the base of the rods
I was able to see and feel some movement. I suspect I may have to send the
crankshaft off to get the rod bearings replaced. I was hoping this would not be
the case but am not surprised. I may also send out the cylinders and pistons to
get them checked as well. I know I need new rings but am not sure about
pistons. I also received a care package from BenchMarkWorks.
I ordered a gasket set, crankshaft bearings, the oil filter adapter and a few
other parts. The oil filter adapter is a neat little gizmo.
1 May 2003 - I spoke
with Ed Korn about my crankshaft. It should not have
play in the rods. I decided to send off the crankshaft. I was going to take off
the valve covers so I can go ahead and send the cylinders and pistons in to get
the checked out. Things come in two's, or is that three's. Today I attempted to
remove the valve covers from the cylinders. All of the nuts came off except the
nut above the exhaust on each cylinder (see red circle). I heated them up
red-hot but they would not break loose. They were rusted solid. It looks like I
am going to have to cut them off.
2 May 2003 - Today I cut
the two bolts off that were holding the valve covers on (one per cover). The
photo below shows the disassembled cylinders and covers. The cylinder walls
show no scoring and no noticeable wear. Of course the bore needs to be measured
for wear.
With the covers off, I
started to clean the caked up gunk off of the cylinders with a screwdriver in
preparation to soak them in the parts cleaner. I found another spot the serial
number is stamped. It is in the cylinder housing near the valve adjustments.
Both cylinders match the frame (more good news, photo below)
May 3 2003 - I degreased the cylinders and valve covers. The valve covers are now
ready for sandblasting. The cylinders, crank, and pistons will be sent off to
Ed Korn. I cleaned off the top of the carburetor and
found some interesting markings on the top plate. I think the lower line may
refer to jet sizes.
May 4 2003 - Cleaned and sandblasted valve covers.
Photo below shows one blasted and one degreased.
May
21 2003 - Progress is slow
and not much is worthy of website update. I am cleaning nuts and bolts. I had
to replace one of the studs that secure the oil filter cover as it snapped in
half. It is 6mm with ~ 30 threads per inch (not typical for the US - and I
wonder if it is in Europe). I went to a local specialty fastener warehouse and
it was something they could not order. I decided to convert it to SAE.
1/4" - 28 is very close to the original size and pitch. I drilled out the
old threads and installed a helicoil.
May
30 2003 - I am having
NU-Chrome in Fall
River MA cad plate the hardware for the engine. They have
gotten the parts. I got an email today from Ed Korn.
He is doing my crankshaft cylinders and pistons. He has measured the pistons
and cylinders and I am getting replacements made.
He sent the follow data:
Cylinder A
Max Cylinder diameter 3.0760 (78.13mm)
Piston Diameter 3.0615 (77.76mm)
Piston to Cylinder Clearance 0.0145
New (Clearance) 0.0025 wear limit 0.007
Max taper 0.0045
Max out of round 0.0015
There are (no pits or scores) fins (are
undamaged)
Cylinder B
Max Cylinder diameter 3.0795 (78.22mm)
Piston Diameter 3.0655 (77.86mm)
Piston to Cylinder Clearance 0.014
New (Clearance) 0.0025 wear limit 0.007
Max taper 0.0075
Max out of round 0.0055
There are (no pits or scores) fins (are
undamaged)
27
August 2003 - Today I
measured the thickness of the two clutch disks. Vech
of Bench Mark Works offers clutch disks on exchange. The overall thickness of
the renewed disks is 6.6mm (0.2598"). My disks were:
#1 5.89mm
(0.232")
#2 5.74mm
(0.226")
The material on both disks has a little bit to
go before it hit rivets. I am going to try and find out what the minimum
serviceable thickness is before I decide to trade them in.
2
February 2004 - I received
my heads back with two of the studs replaced and the threads on the others
cleaned up. A summary of the work I had done on the cylinders. They were bored,
powder-coated, new valve seats, valve job, and new pistons.
A brief note on some of my
original fasteners that I had CAD plated. After sitting for a bit they started to tarnish in spots. I decided to
buy the stainless fasteners that Vech has available.
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I removed the magneto
chain by removing the clip on the link and then the link that holds the chain
on. Next I removed the screw on the top of the magneto-securing band and
removed the magneto.
Once the bolt was removed
I heated the engine case at the front and rear of the camshaft where I thought
the bearings might be. I tried to use a gear puller to extract the camshaft but
could not get it around the front gear. I decided to tap the camshaft out by
tapping on the back of the front bearing housing. I was able to tap it out but
the housing has some marks from the tool that I will need to smooth out. The
photo below shows the camshaft and the valve tappets. I removed the tappets
from the ends of the cam followers (they contact the cam lobes) thinking I
could then get the cam followers out of the engine housing. Wrong, apparently
the bushings that the cam followers are in need to be pressed out of the engine
housing in order to get enough clearance to remove the followers. I decided not
to remove them as they appear to be in good condition.
1 May 2003 - I spoke
with Ed Korn about my crankshaft. It should not have
play in the rods. I decided to send off the crankshaft. I was going to take off
the valve covers so I can go ahead and send the cylinders and pistons in to get
the checked out. Things come in two's, or is that three's. Today I attempted to
remove the valve covers from the cylinders. All of the nuts came off except the
nut above the exhaust on each cylinder (see red circle). I heated them up
red-hot but they would not break loose. They were rusted solid. It looks like I
am going to have to cut them off. 
2 May 2003 - Today I cut
the two bolts off that were holding the valve covers on (one per cover). The
photo below shows the disassembled cylinders and covers. The cylinder walls
show no scoring and no noticeable wear. Of course the bore needs to be measured
for wear.
With the covers off, I
started to clean the caked up gunk off of the cylinders with a screwdriver in
preparation to soak them in the parts cleaner. I found another spot the serial
number is stamped. It is in the cylinder housing near the valve adjustments.
Both cylinders match the frame (more good news, photo below)
