Building a Puch for classic racing.

Through the Dan Jeppesen- Puch project I experienced the qualities
of this Austrian make and during the talks with Albin Sterbenz, he
pointed out the ruggedness of the 337-50 type engine. And rugged it
is compared to any 50cc engine - the Maico being an exception as it
is based on 125cc crankcases. The Puch shares bore and stroke with
the Kreidler as well as a chromed cylinder, but clutch and transmis
sion dwarfs even some 80cc cross bikes. Many Puch models carried
this engine, and two different crankcases were produced to cover
both tube- and pressed steel frames. Here in Denmark, we saw this
engine in the MC50 Super only. More than a hundred of them actually
with 11,2hp engine, and two with 14hp!
First time a 337-50 engine is known to be used for road racing,
were in the Austrian national championship, in early 1974. Same
year Pennti Salonen participated in some world championship races,
with a Tunturi Puch also carrying the same engine. Puch 50cc motocross production model MC50 Super.

Puch Cobra MC50 Super engine.

Disc valve conversion.

Race frame for the 337-50 engine - dec 2013.

DeJager style frame with Cobra engine.

DeJager Puch - january 2014.

Ready for fairing.

New pattern for the headstuds.

Reversing the crankcase bolts.

More pipes - hopefully one will do the trick?

Angled primary drive and clutch - will be exchanged. Straight cut primaries.

Dry clutch setup.

Pre- Cobra engine. Sandcasted.

Pre- production Puch 337-50 engine, sandcasted early version of the Cobra. Notice the symmetrical bolt- pattern for the cylinder/ head and
large, square shape of the cooling fins. Upper surface of crank-
case reveals that this engine also have the left crank mainbearing
lubricated with transmission oil like the 299xxx series seen at
right, which features twin seals at left side of crank.

Fabricated set of straight cut primary gears for original clutch.

Update to the Cobra roadrace engine - straight- cut primary gears for use of original as well as Honda style clutch.

Fabricated crank primary and clutch shaft destined for a Honda dryclutch.

Honda CR clutch adapted to 337-50 Cobra engine.

Dry clutch progressing. Using Honda parts....

Cover for dryclutch.

Seal should go in here. Dry clutch and actuator.

Some progress....

First startup.

13/34 ratio first gear with needle bearing. Straight- cut primaries - original style.

E-T Cobra engine #3...

E-T Cobra dry clutch.

Latest version of the Cobra dryclutch.

Rotating assembly from the factory MC50super.

Needle bearings in trans and clutch - straight- cut primaries and crankshaft without shock- coupler.

Another Cobra engined special:

Tunturi Puch replica being assembled.

Through the Dan Jeppesen- Puch project I experienced the qualities of this Austrian make and during the talks with Albin Sterbenz, he pointed out the ruggedness of the 337-50 type engine. And rugged it is compared to any 50cc engine - the Maico being an exception as it is based on 125cc crankcases. The Puch shares bore and stroke with the Kreidler as well as a chromed cylinder, but clutch and transmis sion dwarfs even some 80cc cross bikes. Many Puch models carried this engine, and two different crankcases were produced to cover both tube- and pressed steel frames. Here in Denmark, we saw this engine in the MC50 Super only. More than a hundred of them actually with 11,2hp engine, and two with 14hp! First time a 337-50 engine is known to be used for road racing, were in the Austrian national championship, in early 1974. Same year Pennti Salonen participated in some world championship races, with a Tunturi Puch also carrying the same engine.
















	Pre- production Puch 337-50 engine, sandcasted early version of the Cobra. Notice the symmetrical bolt- pattern for the cylinder/ head and large, square shape of the cooling fins. Upper surface of crank- case reveals that this engine also have the left crank mainbearing lubricated with transmission oil like the 299xxx series seen at right, which features twin seals at left side of crank.