TATRAN 50cc and 125cc RACERS
Some facts and Figures supplied by Lukáš Hromádk
Lukáš has been a motorcycle racer and is now a collector of the Tatran bike marque, racing models and an archivist of its history. Currently Lukáš is writing a book in the Czech language about the Racing and Enduro models of the Tatran and of their production in the Povazske Strojarne factory. He was a great help in the production of this page.
"I must state here quite emphatically that the JAWA factory had nothing to do with the creation and manufacture of these motorcycles”. Lukáš Hromádka
Lukáš was Speedway racing for 10 years from 1962 and his first bike on the speedway track was a Jawa two-stroke. Now, for him the interest is in the fantastic Classic Racing, Motocross, Enduro and Speedway motorcycles are his love but especially the Tatran 50cc racing motorcycle which is the Bedrich Fenrich version.
The following is a collection of messages from Lukáš giving information on the PS factory and the Tatran marque. I have re-written some but have not changed to context. Lukáš: “My Tatran is an 50cc RS, type 104 water-cooled factory machine and the Bedrich Fendrich (#47) machine which he campaigned so successfully".
This is one of only three machines made by the Tatran factory, on the left is the factory rider Otto Krmicek and on right, Oldrich Prasil who was the factory mechanic. This man hand built the first air cooled Tatran racer of the same type as the Terry Larner machine in the Classic Racer article”.
Lukáš Hromádka "These are my castings from moulds that I made for my replica Tatran engine which took me 4 year hard work to make !!!! These made a good quality replica crankcase and covers for my Tatran Enduro and Tatran Racer (the factory used the same crankcase castings for both engines) I built this from using the original factory drawings plus original parts"
This gallery of pictures, is of the Bedrich Fenrich Tatran engine when Lukáš stripped it for the re-build.
Back to the Factory
"The Tatran road racing project was created, as a black or secret project in the development workshop and was started by Oldrich Prasil for their racer Bohumil Kovár, from the Tatran Enduro motorcycle using the 6 gear transmission".
"In January 1964, a 50 cc motorcycle engine, with a 5 or 6 speed gearbox was introduced. This engine was developed to have a common road and off-road design. This was the first of the successful TATRANOV 50 RS series. It was air cooled and would have been one of those used in building the 'Larner JAWA'".
This new motorcycle was designed and built by Jozef Mandáček. Apart from the Motoforza fairing, he did the complete construction himself. It was also he who built three TATRAN racing motorbikes that are now in the museum. You can see the entire collection of motorcycles at the Museum of the White Carpathian Region, at the chateau in the village of Bohunice. The acquisition of the motorcycles was realized with the financial support of the Ministry of Culture of the Slovak Republic.
You can see the entire collection of motorcycles at the Museum of the White Carpathian Region, at the château in the village of Bohunice. The acquisition of the motorcycles was realized with the financial support of the Ministry of Culture of the Slovak Republic.
With the Tatran sport engine, that was introduced in 1964, a batch of production racers was built in 1965. A chassis of this bike was also produced in a off-road sport motorcycle mode 'Enduro' using with the same engine. Having a 6 speed gearbox, a rotary inlet system, and a dry clutch, the engine was very modern for its time. But the chassis was not a very bright construction. So a lot of race drivers started building their own chassis around the Tatran engine. To this end, in 1969 Tatran tried to make good their mistake with a more modern frame design for the second type of production racer: The TATRANOV 50RS VMW.
"These were then made from the design drawings created by two people Oldrich Prasil who worked from 1964 until 1969 and one more person named Miroslav Werner (I do not know exactly in what year he came to the factory but he was there until the end of the development department of the road racing motorcycle in 1973. He was also the mechanic to the most famous Czech motorcycle Tatran racer Bedrich Fendrich". Bedrich Fendrich Please click to go to his page
"The designer/ builder of these racing bikes was the factory’s leading constructor Ing. Zdeno Nagy". These motorcycles were designed and built in the Povazska Bystrica factory".
At this time the factory also produced for the JAWA Company, the 90cc engine, a sporty rotary valved model for the export markets. This Jawa 90 was a simplified version of the Povaszke Strojarne factories special motorsport engine.
The Jawa 90cc engine was quite a popular unit to build race bikes with and some were sleeved to 50cc. These racers are often declared wrongly as Tatran. The JAWA 90cc engine is a more compact unit compared to the early Tatran engine that it was based on. Due to a change in the gear-shaft arrangement inside the JAWA 90, as with the new Tatran engine, has a curved hump on it's back to accommodate the 6 gear cluster. JAWA never made 50cc factory racers, the small classes were Tatran territory.
Having a 6 speed gearbox, a rotary inlet system, and a dry clutch, the engine was very modern for its time. But the chassis was not of a very bright construction. So a lot of race drivers started building their own chassis around the Tatran/JAWA engine.
This is an example of the Cold War racers developing their own race bikes from the parts available. This one is using a sleeved down version of the JAWA 90cc motor which had a good reputation for tuning.
There are no details of the specification or history of its use. Some of the updates to the build include the water-cooling system, a new magnesium cast front brake and a change from the upside-down front forks. It still appears to have a 6 speed gearbox. There are changes to the frame design and the swing arm is now in box tube.
Jeep: If anyone has further details I would welcome them and would include them in the page. If the photographer would care to contact me and allow me to continue to use them I will happily add his name as the owner of the copyright.
To address this situation, in 1969 Tatran tried to make good their mistake with a more modern frame design for the second type of TATRAN production racer. After some re-engineering it was labelled the 'TYPE 104' and as part of the up-grade was given water-cooling to aid the power range.
The 'TYPE 104' had the spine frame of the off-road types but was a lower, individual structure for the racer. At the front, instead of pressed steel forks with a swing arm movement it had a 100 mm stroke telescopic fork. The rear spring units have their stroke reduced to 80 mm. Smaller 2.25 x 17 inch wheels and tyres guarantee a significantly lower machine build.
For off-road bikes, the wheels and brake hubs were from the J-05 model and were used on the racer from the start. The glass fibre laminated race tank has a low sleek profile allowing the rider to fit tight into the bike reducing air resistance. The bike was complimented with a racing seat, frame and a nicely shaped fairing. The engine was the two-stroke, single cylinder, water-cooled. It maintained the suction-controlled rotary disc valve.
The water-cooled, reversed cylinder had different port timings between the racers and off-road bikes air-cooled units. It also had the rear facing exhaust port allowing a better shaped expansion system to be manufactured, using the knowledge and skills of Walter Kaaden, and a better fitting within the frame. The cylinder had three transfer ports with the one exhaust port. The 40mm stroke combined with a bore of 39.6mm gave a capacity of 49.76 mm.
The engine does not have a starting system and a push start is required. The rotary disc induction system allows the horizontal carburettor to be fitted with a very short suction channel. The dry uncovered clutch is a substantial unit, more than capable of managing the power of the race competition engine. According to the catalogue data, it should have a compression ratio of 14.5:1 and develop 8-9 HP, 14000 rpm, giving a maximum speed: 142 km/h. (Jeep)
Tatran 125cc Czech Republic -a -New Racing Machine
Lukas: "Few people know that the Tatran 125cc twin was originally produced by building a Tatran 50cc twin engine. However, because in 1968 the FIM banned all two-cylinder 50cc engines, this project was not completed, it was ready for the 1969 season in two versions but the engines were destroyed in the factory and there is no picture. Some parts were used on the Tatran 125 Twin. The 50cc motorcycle does not exist but I know there is a chassis and a part of the engine. I have 30% of the drawing documentation from this motorcycle". Fendrich Bendrick on the TATRAN 125cc
Jeep: Following on from Lukáš comments I carried out some research but could only find one reference to the 125cc twin and nothing for the 50cc twin. The FIMs ruling for the 1969 125cc or 50cc GP, outlawing multiple cylinders and the 125cc, restricting it to a twin cylinder only. This stopped a tremendous amount of research and development by manufacturers from using some of the advanced technology in small engine efficiency and economy which would have benefited the public.
I have translated the following from a German language magazine and I hope it reflects the context of the information that was available. I have made changes and additions for a better read.
The company Pouazske Strojirny is based in Slovakia and has supplied engines and complete motorcycles to CZ and JAWA for a number of years. These have been to the customers specifications but with a great amount of development work from the TATRAN Development Department. A large amount of this work has been in improvement and promotion of the customers road bikes but evidently the development work in the sports motorcycle sector was not only for the likes of CZ and JAWA:
"A Czechoslovakian magazine journalist sent us pictures of an interesting road racing machine, which was created recently in the motorcycle factory of Pouazske Strojirny in Slovakia. This is the factory in which the Czechoslovak Manet -Roller was built along with the Tatran motorcycles and racers, and where they are now assembling this bike under the their brand name and that of of JAWA, along with running 50cc, 75cc and 90cc rotary valve two-stroke motorcycles".
Unfortunately, we do not have any further details about the engine and transmission. Only so much has been told to us for example a transistor ignition of Slovak manufacture is being used and the source also finds that the engine will rotate to 15 000 rev/min and that the machine should reach a top speed of 200km/h under favourable conditions. The 18-inch wheels are running with a 2.50 tyre on the front and a rear tyre of 2.70
The two Czech designers Zdenek Nagi and Antonin Hajek are the fathers of this water-cooled two-stroke, twin cylinder. racing machine seen presented here which, as the pictures show, has two rotating disc valves, one on each of the two crank housings with its own single-carburettor control and is consequently, the power control for such two-strokes transmission.
In the pictures you can also see the ignition system: obviously an AC generator with two separate coils and the transmitter for the plugs which is mounted with the remaining parts of the electro circuitry at the bottom of the high-voltage coils.
It is interesting to note the remarkable similarity in the design of the frame, tank and seat between the 125cc Twin and the Tatran 50cc single.
The Terry Larner 50cc JAWA
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