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#Post#: 88114--------------------------------------------------
Sachs Dolmar 122 rebuild
By: Yozhek Date: June 21, 2021, 2:49 am
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Hi,
My name is Ade, i am now of an age that folks here in the UK
call 'second childhood'. OK so i still have control over my
bowls and i don't dribble (except for when i see a KMS-4), but i
do have some fond memories of my first job working for a small
garden machinery company and some of the saws and generators we
sold and repaired. Back then Dutch Elm diesease struck the UK
and we sold lots of Sachs Dolmar, 118, 122, 144, 152 and i think
2 KMS-4, plus Pioneer and some Homelite.
122's were the most popular, good tough farm saw with magnesium
castings, ball bearing mains, Tillotson Carburettor and
Antivibe. So when an early 122 came up for sale on EBay i bought
it just because i like them :-)
The saw wasn't i too bad shape externally but the cylinder was
scored quite badly, looked like it had seized at one time. Time
to strip, clean and check what parts were OK and which were bad.
[attachimg=1] [attachimg=2] [attachimg=3]
The chain/clutch cover was broken but thanks to those great
folks at Chainsawr i have a new one, decals are of course wrong.
Also someone drilled holes in the cylinder cover to fit a
horrible hand guard so i kind of covered it up with a 122s hand
guard until i can find better.
[attachimg=4][attachimg=5][attachimg=6]
Antivibration mounts are a comon failure on 122's and four of
the five has split apart, lucky they are available as pattern
parts. Fuel tank vent rubber sleeve had long since split and
gone. The oil tank was filled with old engine oil and needed a
good clean out, lucky the clunk pipe was in good shape. Fuel
tank gasket failure is not uncommon on these saws but the early
ones vented the oil tank through the gasket, later models had a
jiggle pin vent.
[attachimg=7][attachimg=8][attachimg=9]
[attachimg=10]
Once i get the engine parts i will post some more, thanks for
reading :-)
#Post#: 88124--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Yozhek Date: June 23, 2021, 11:55 am
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Crankshaft and crankcase.
The original crank looked good but was a little bent on the
chain side
[attachimg=1]
Chainsawr to the rescue again, they had a NOS crank and proper
122 crankcase gasket. The crank was quite rusted but the big end
was waxed and good, 15 minutes with some Jenolite got rid of the
lumps of rust on the shaft and it was good to go ;D
[attachimg=2]
[attachimg=3]
The 122 crank is a tight fit in the main bearing on the chain
side and a sliding fit on the flywheel side, i find it easiest
to warm the main bearing and oil pump worm gear and drop them
onto the chain side of the crank first
[attachimg=4]
[attachimg=5]
Then warm the crankcase and drop the crank assy in
[attachimg=6]
Next warm the flywheel crankcase and add that main bearing,
followed by the oil seal. The old stock gasket was hardened with
age but a little grease softened it and helped it fit.
[attachimg=7]
Once the seal lip was greased it was time to assemble the
crankcase. The crankcase halves can get slightly rotated in
relation to each other resulting in a bit of misalignment on the
cylinder base gasket face, this can be prevented by temporarily
bolting down the cylinder to align everything before final
tightening of the crankcase screws.
[attachimg=8]
[attachimg=9]
Bottom end nearly done, thanks for reading.
Ade
#Post#: 88125--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Yozhek Date: June 23, 2021, 4:33 pm
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Oil pump
The Dolmer 122 achillies heel, the oil pump is driven off the
crank by a worm gear and pumps using a piston with a cam and
spring mechanism, the flat on the end of the piston working as a
rotary valve. The pump never wears out but the worm gear pair
wear rapidly if engine lubrication is less than perfect and
eventually the teeth strip resulting in a loss of bar oiling.
Dolmar modified the pump twice during the 122's lifetime, first
the drive end of the pump was extended to form a support bearing
(122S) and secondly the whole pump was moved from part of the
crankcase to a seperate casting as in the later 123 saws (later
122S & 122SL).
As this saw is an early 122 model it has the early type pump,
for which parts are no longer available. Lucky for me the pump
was not in bad condition, the worm gear has some life left and
fitting it on the crank in the opposite orientation presents
unworn gear teeth to the pump pinion. The pump was showing wear
but as only the later 122s type pump piston is available as a
spare part i had to modify a 122s pump by removing the support
bearing with a lathe and increasing the depth and diameter of
the spring recess with a carbide drill.
[attachimg=1]
Thanks for reading :-)
Ade
#Post#: 88126--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Chainsawrepair Date: June 24, 2021, 5:54 am
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Very nice work. [emoji1303]
#Post#: 88129--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Yozhek Date: June 24, 2021, 5:08 pm
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Thanks Cut4Fun :-)
#Post#: 88130--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Yozhek Date: June 24, 2021, 5:21 pm
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Clutch and Magneto
With the oil pump back in the crankcase, the oil flow adjuster
fitted and everything checked the pump side oil seal can be
pressed in.
[attachimg=1]
[attachimg=2]
There were two types of clutch used in the lifetime of the 122
series, both are interchangable, the early ones had bonded
clutch shoes, they didn't wear the clutch drum out like the
later all metal clutch but if they got overheated or oil soaked
the clutch lining would come unbonded and could wear through the
side of the crankcase. The clutch on this saw was dry and in
good shape so it was refitted.
[attachimg=3]
The 122 and 122s used a Bosch points magneto, these things are
indestructable, in all the years i worked with these saws not
one replacement part was ever needed for one of these magnetos.
All i had to do here was clean the points, add some grease to
the points pivot and cam wick and check the gap was 15 thou,
perfect spark...
[attachimg=4]
By the way, the points cam fits with the key piece toward the
flywheel and the wavey washer under the cam not on top.
[attachimg=5]
On with the flywheel, fan and starter dogs
[attachimg=6]
And we have something looking like a saw again, just got to be
patient while i wait for the barrel and piston to come from
Chainsawr.
[attachimg=7]
Thanks for reading
Ade
#Post#: 88133--------------------------------------------------
Re: Sachs Dolmar 122 rebuild
By: Yozhek Date: June 25, 2021, 7:46 am
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Final assembly.
I got a present in the post this morning from Chainsawr
[attachimg=1]
Nice NOS barrel and piston
[attachimg=2]
Piston, barrel and exhaust all fitted
[attachimg=3]
This saw has a Walbro SDC carb instead of the later Tillotson
HS-148A, this makes me sad :(
[attachimg=4]
Chainsawr managed to find me 2 new O rings for the oil pump,
good job the pump can be removed without taking the clutch off
again ;D
[attachimg=5]
[attachimg=6]
Finally all done, runs very nicely, smooth and quiet like it
should. The carb is leaning out after prolonged idle so need to
get some new diaphragms and check it.
[attachimg=7]
[attachimg=8]
Many thanks for reading this far :-)
Ade
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