History behind the Raket Karting Engine success

Which go-kart engine has been manufactured in most copies? Yamaha? Rotax? Some Italian brand? No, the answer is that the engine that is not only manufactured the most but has also been in production and use for the most years, is an engine called Raket and it is still going strong. You can read about the history of the engine below.

At the end of the nineteenth century, the Italian engines Komet, Saetta and Parilla dominated the market. New engines were constantly developed every year, with more power, which was usually applied at even higher rotation speeds. Sure, these were exciting engines, but they were also expensive and not always the safest. This led to go-karting becoming more and more an expensive elite sport, as there was no class for young drivers or drivers who wanted to race for fun, drivers that couldn’t afford two or three engines per season. By the way, at that time there was no mention of go-karting, which was the original American designation, but the sport was called Formula K.

In the mid-sixties, attempts were made to introduce classes that could become more popular by competing with simpler, cheaper and more reliable engines. Such a venture was called Class A Popular. For this class some remodeled chainsaw motors were homologated, including an older 90 cm3 engine from Partner. Common to the engines in the class was that they were equipped with a reed valve. This ingenious invention fits very well with a membrane carburetor, and normally provides motors with good torque at low and medium speeds. The reed valve also automatically becomes a speed limiter. 

However, Class A Popular did not become as popular as the Formula K committee had hoped for, at least not until converted Italian engines that had been equipped with reed valves appeared. Then, of course, the situation became that those who had Italian engines could do laps around those who had a Partner or Husqvarna engine. And there the fun ended. The Formula K committee once again found that it was not so easy to invent a class where you could not buy a prize on the podium with the help of a thick wallet.

Then why did no one come up with the brilliant idea to produce a simple, cheap and reliable go-kart engine that also looked tough and did not look like you had dropped a chainsaw behind the backrest on the kart? The answer is that some components such as piston, cylinder and crankshaft must be manufactured in very large series in order to come down to acceptable unit prices. The attempts that had been made with chainsaw motors were permissible, because they used a bunch of components that were available, and these kinds of engines are normally very reliable. The mistake that they had made was that they had retained too much of the chainsaw, so that the real go-kart feeling was lost.

Background with Partner

In the early seventies, a development team at Partner in Mölndal worked on producing a series of chainsaws with 85 cm3 and 100 cm3 cylinder volume respectively. This is quite a lot for a chainsaw, as the saws were intended for exotic markets where they worked with the really big trees, for example in South America. Production-wise, the two models would very similar even down to the piston and cylinder. In 1971 and 1972, these engines were put into a brake dyno to optimize performance and reliability. The brake dyno engines consisted of a simple sand-cast crankcase, a simple fan cover but otherwise with completely correct components such as crankcase, cylinder and ignition system. At the end of 1972, the tests were completed and Partner ordered production tools for the new chainsaws. A young man who worked in the lab quit the company at the same time and wondered if he could bring some of the test engines as a memory.

Creating the Youth Class

The following year, Leif Radne and former Partner staff member Bo Sörensson met and the idea of a new engine for a youth class came to life. The test engines were then brought back, and Leif Radne turned and pondered and scratched his head. A sand-cast crankcase and a fan cover, that could be arranged. Buying a piston, cylinder, ignition system and carburetor from Partner? Hm, Hm maybe - we have to think about it. And as it is said in such contexts, the rest is history. Once at home on Violabergsvägen in Vendelsö, Leif sat down and redesigned certain parts, such as the crankcase, to make it suitable for go-karting. A first test series was made, half with 85 cm3 cylinder and half with 100 cm3 ditto. Test driving at the karting track Ös-We-ring showed that Leif was on the right track. Not only did the engines, which were initially called Partner RS85 and Partner RS100, behave well, they looked like go-kart engines, they sounded like go-kart engines and they even smelled like go-kart engines.

Leif took the engines in a box and went to the Car Sports Association and presented the new engines to the Formula K committee. The result was two new classes one for each cylinder volume. Other engines with the same background also made some lame attempts, but from the beginning the engines from Radne Motor came to dominate. It turned out that the 85 cm3 engine was virtually indestructible, while the 100 cm3 engine had many problems with cooling. Therefore, after a few years the 100 cm3 variant was discontinued, and the 85 cm3 engine became homologated for the Mini and Micro classes.

Long Term

What is it said about the original Volkswagen, that although the look was largely maintained, there were no parts from the original that fit in the latest year models. With the Radne Motor engines, components are almost exactly the opposite. Of course, a lot has changed. The sand-cast crankcase is now cast-molded, the fan cover is plastic and, by the way, the engine is no longer called Partner, but Raket. But, if you have a 1974 cylinder, or a carburetor or crankcase, well then they still fit in a brand new 2014 engine. This has been an important principle for Radne Motor, not to change what is already working well. If you have bought an engine for one year, you should be able to ride with the same stuff for several years and not have to change to a new model every year. It will also be the benchmark for the future. As long as Radne Motor can buy the basic components, the Raket engines will continue to be largely unchanged, though constantly improved.


One of the big and heavy molds for the engine Each weigh over 100 kg and is made from homogeneous steel

Over Fifty Thousand Engines

Since its first successful start in 1974 until this year, Radne Motor has produced more than 50,000 Raket engines. Today they are used in youth classes such as Mini and Micro in many places on our earth. From Radne Motors warehouse on Markörgatan 2 in Handen, Raket engines are shipped to several European countries, but also to happy riders in Russia and far away in New Zealand. Raket engines are not only used to compete with, there are models for rental karts as well as for hobby use for those who do not want to compete but think it is fun to be able to race every now and then. A strong increase in the use of Raket engines is for flying. Yes, it's really true. For the lightest machines like Ultra-Light Aircrafts and hang gliders and paragliders, the Raket motors are engines to rely on. They are then equipped with propellers, either directly on the crankshaft or via a gear. Next time you hear something buzzing in the air, look up, there is a high chance that it's a Raket on a paramotor.

Where are the Radne - Raket Engines Made?

Do you want to know how and where the Raket engines are manufactured today? Then you are welcome to the factory in Handen. The crankset is manufactured in Sweden, and the piston and cylinder are manufactured by the German company Mahle. The crankcase is cast in south Sweden, the carburetors come from Ireland. All these components are purchased, checked and stocked at Radne Motor. Here also the final assembly and final inspection takes place. Production is about 30 engines a week if we count all different types.

There is a stubborn reputation that there are specially selected engines that are a snap better than the normal engines. Anyone who has seen the stock with hundreds of cylinders, hundreds of crankcases and so on and seen that all are checked against the same templates and that deviations are within extremely strict tolerances, understands that it would be a hopeless task to find just the combination of all the components that could give any driver an advantage on the track. Especially if you consider what a tremendously greater impact a properly tuned carburetor has. And finally, the biggest difference between different vehicles is to be found in the person behind the steering wheel.

Fifty Years

Wait a moment, the first production was in 1974. In 2014, this means that the Raket 85 engine will celebrate its 40th anniversary. How many engine brands can boast of having been at the top for forty years? No, there will be no anniversary model. Radne Motor does not want to contribute to the rumor that there are engines with different performance. 

The founder himself, Leif Radne, who has more than fifty years of experience in the go-kart industry, defines a good Raket engine as the engine that gives all drivers the same conditions - it should only depend on the driver, and to some extent, the mechanic.

You are welcome at any time to call us and talk about our engines


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