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We have been testing and testing with our Rok engine, mounted on a Tony chassis, and after months of testing we can recap this long period.
Start and mode of testing
We started at the beginning of the year with our Tony Rok that had raced twice and was in good conditions, maybe with about 2 hours of running already. We decided to proceed with our testing month after month without doing any great maintenance, apart from using chain grease and putting mixture in the tank. All the rest was limited to chassis setup, tires substitution and some cleaning. This was done since we wanted to find out the reliability of such kart, especially the engine, for someone who had no idea at all on how to maintain a kart. Even carburetion was always kept at its standard value…and this worked all year perfectly, until our latest test, done in very extreme conditions
Long test diary
First of all we must say that our long test had the aim to verify the duration of the engine, as already said without any maintenance and tuning (carburetion first of all). So we went along with our testing month after month and were waiting for something to happen to the engine sooner or later. What was surely incredible was the fact that it was possible to run each time with the same carburetion from March until now, with extremely great temperature and humidity differences. Engine worked always well, with good performance and incredible reliability, something I never experienced with 100cc direct drive engines or any other kart competition engine.
From March to May – total 7 hours, no problem at all!
We ran with the Rok about 5 hours of testing, which had to be added to the 2 hours of racing done before we received the kart from Tony. Never a problem in this phase. We just took the kart to the track, put mixture in the tank, grease on the chain..and ready to go! This is something that you cannot really afford with other competition engines, and surely puts in evidence how good such a solution is for any driver who wants to use a lot his kart and eventually do some racing, always with good performance but no real fuss to look after the engine.
June to September – 11 hours, just a spring of the clutch braking. Rear barking pads worn
Still very good functioning, also the chassis was incredible. The Esprit adapted to all tracks with great easiness. No setup change or only slight adjustments were needed for good performance. Any regulation of setup also gave very good reactions to behavior of the chassis indicating wide range of possibilities to adjust the kart to driver’s needs.
Only stop we had was with the clutch where a spring broke and, even if the clutch still was working, we had to fix (easily and quickly) for good functioning. The spring system is actually the old clutch system and today the new clutch does not have springs any more as to avoid them braking.
Also rear braking pads had to be changed. No malfunctioning, just simple wear, that impacts much more rear brake of course, then front brakes, which are used less and are also double.
October to November – 13 hours, clutch pads worn.
Clutch wear problems occurred. This also happened because a difficulty we had once starting the kart because the battery was low. This led to a heating of the clutch and a deterioration of the pads with subsequent fast wear. A fast and easy change solved the problem.
December – 15 hours, carburetion to be adjusted. Rear brake pads worn.
In a freezing Winter day, with temperature between 1 and 5 °C we decided to go testing and try some new LeCont tires, recently tested with good results at the group WSK testing with many of the major International brands, such as Tony, Birel, CRG, Kosmic, at La Conca track in Italy, after the Nations Cup Final. The new tires built with new oils much “greener” then the previous as for new International regulations. In the specific day LeCont had good performance (not best of all, but good), and where appreciated mostly because of the constant behavior lap after lap.
So we were ready for deep testing of the tires, but after about 10 laps we had the feeling the engine was not performing as well as usually and we decided to stop and open the engine cylinder…for the first time!!! We found a “suffering” piston with worn crown probably derived from very poor carburetion determined by the freezing weather conditions. As we know the colder the weather the riches the carburetion must be and vice versa. If we consider we had ran with the same carburetion setup in August in Italy, maybe we had asked too much to the engine. The piston showed the crown was somehow deteriorating, loosing bits as if it was crumbling down. This effect is determined by detonation generated by poor carburetion. When fuel/air mixture is poor the combustion is not uniform and small explosions are generated in the combustion chamber, especially in the areas further away from the spark plug where combustion starts. This can be easily seen looking at the piston from the top, where a light colored crown can be seen, indicating very high temperatures and detonation.
On the other hand cylinder head was in perfect conditions showing the engine works fine and is never challenged too much in its base setting. This is also the reason why the engine did not seize. So on one side we understood it was time to stop, on the other we thought that only a good reliable engine as the Rok could go on running without seizure in such conditions and we once more had the feeling that one of the best choices for all who want to start running with a kart and one day also try racing, is surely to go for the Rok.