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The new appointment with “Ask…”, the space dedicated to the answering the experts TKART readers’ questions. Once again, it is Franco Drudi head of TM Racing engines development department, to clarify kart drivers’ doubts regarding engine’s maintenance and provides specialized tips on basic preparation. Although it is true that 2-stroke engines are the combustion engines with the simplest operating principles, it is equally evident that there is always something to learn from one of the most qualified and successful engine specialists in the paddock.
Rather than being maintenance wizards, one must commit to maintaining the engine correctly. More damage is done on the track than in the workshop! For example, persisting on using a carburation that is too lean can shorten the useful life of the connecting rod, or downshifting without braking, as I see many beginners do, this can cause serious damage. Always remember to perform a proper breaking-in when the engine is new or that has been overhauled and, above all, use a good quality oil recommended by the manufacturer.
First of all, it is necessary to check that there is oil in the gearbox. Better safe than sorry! Then, yes, a good break-in extends the life of the engine significantly. The most common general advice is not to accelerate for too long when the kart is on the stand, because vibrations cannot be discharged to the ground through the chassis and tires. Therefore, the vibrations can possibly affect the engine in an adverse way, as they cannot be transmitted to the track. During the break-in process, you should never upshift or downshift gears too abruptly. Additionally, make sure that the water temperature reaches 50° C while the engine is warming up. In cold weather it is a good idea to cover the cylinder to retain the heat.
Let us say that reed valves, over time, lose their reactivity. They no longer flex as they should, that is at the right frequencies and amplitudes. But, they hardly break, especially those used in the KZ. As for the replacement, I would do it every 3 hours of use for an OK engine while on a KZ used for fun I would change them every two revisions or, at the limit, every 25 hours.