The KTM 50sx and 50 Mini can be very aggressive bikes right out of the box; they are made for racing after all. Many new riders won’t be expecting the sudden acceleration which can cause them to be thrown to the rear of the bike, or even worse, they could end up whiskey throttling and lose control of the bike altogether. Lucky for us, KTM offers an adjustable clutch. This allows parents to wind down the clutch so when the rear tire engages, it won’t be as aggressive. As your child becomes more comfortable, the clutch can be wound up giving them a more forceful take off suitable for racing.
Tuning the clutch on these dirt bikes is simple and easy. We will start by draining the gearbox oil. Then after removing the clutch cover, we will show you how the clutch works as well as how to adjust the number of clicks. After you’ve mastered tuning, we will give you some recommended settings to try out depending on your rider’s skill level. At the end, we will show you a few tricks on how you can do this at the track without needing to drain the gearbox oil as well as some useful clutch covers that allow for changing the clicks without the need to remove the cover.
We will start by draining the bike’s gearbox/clutch oil. This is most easily performed with the bike on a side stand. A center stand can be used but this makes the process much more difficult. If you don’t currently have a side stand, we strongly recommend getting one for maintenance purposes. Pit Posse offers a universal triangle stand that we find comes in handy.
Draining the Oil
Begin by removing the oil cap from the throttle side of the bike. This prevents a vacuum from forming within the gearbox and will assist in ensuring the oil is drained thoroughly. Next, locate the oil drain bolt on the left-hand side of the bike. Place an oil pan under the bike and slowly remove this bolt. These drain bolts are magnetic, and the tip will collect filings. It is a good idea to thoroughly clean these when changing the oil since they will collect a lot of gunk. Leave the bike for a few minutes to ensure the oil is completely drained. Once sufficiently drained, replace the oil drain bolt and toque to 20 Nm (14.8 lb-ft).
Removing the Clutch Cover
With the oil drained, the clutch cover can now be removed. Locate the clutch cover on the right-hand side of the bike. There are four 8mm bolts holding the cover in place. Remove these four bolts and carefully remove the cover. You may need to wiggle the back brake to make enough room. Be careful removing the cover to avoid doing any damage to the engine case.
Adjusting the Clutch
There are three adjustable bolts that are connected to your springs and they will be used to adjust the clutch. If you don’t see these bolts, rotate the clutch basket until they become visible. We will start by turning these counterclockwise until it stops. Once the bolt is fully unwound, you will want to turn it clockwise until you hear and feel the click. This setting is click 1. As the bolt is turned further clockwise, the click setting is increased. The bolt can be clicked up to a maximum of 17 times. It is important to remember that all three bolts will need to be set to the same click number.
Attaching the Clutch Cover
Now that the clutch is tuned to the desired number of clicks, the clutch cover can be replaced. If needed, replace the old seal ring with a new one. Be careful sliding the clutch cover underneath the break. You want to be sure not to gouge up the case. With the cover in place, reattach the four 8mm bolts. Using a torque wrench, ensure these are tightened to 10 Nm (17.4 lb-ft).
Refilling the Bike with Gear Oil
With the clutch adjusted and the cover replaced, we’re ready to refill the bike with oil. The manual recommends using Motorex ATF Dextron 3. Regardless of whether you have a mini or a pro-senior, the bike will take 200 mL of oil. You’re going to want to make sure that’s accurate and a cheap way to do that is using a small measuring cup like this. Not enough oil and you risk burning everything up and if you happen to use too much oil you can end up blowing your seals. It can be a little tricky getting to the oil fill cap and you will have to use a small funnel to fill it up. Finish by screwing the oil cap down firmly.
Adjusting the Clutch at the Track
It’s possible to adjust the clutches on the KTM 50s without draining the oil and removing the clutch cover. This can come in handy at the track when you have to make a change quickly. This can be done by laying the bike down on its side. Ideally, you want to position it so that the clutch cover is level and no oil will leak out when the cover is removed. To make it even easier, there are clutch covers specifically designed to allow for adjusting the clutch without the need to remove them. These covers allow you to turn the clickers through a small port in the side of the cover and don’t even require leaning the bike over on its side. In addition, this cover holds an additional 50cc of oil. This extra oil will help keep your clutch running cool and slow down the wear.
The KTM 50sx clutch comes from the factory at 9 clicks. This is a good intermediate between an extremely snappy response and a more beginner-friendly option. We don’t recommend going any lower than 6 clicks. In our experience, going lower than 6 clicks results in unnecessary clutch wear as heat builds up. If 6 clicks is still too aggressive, you can always put on a 39 or 38 tooth sprocket. The new sprocket will give it more top end and reduce the torque down low. On the other hand, we wouldn’t recommend going passed 13 clicks. At this point, the adjustments don’t seem to make much of a difference and at this setting, the clutch springs will be frequently wearing out.
Beginner – 6 Clicks
Standard – 9 Clicks
Experienced – 13 Clicks
These are just starting points and we recommend you experiment with your own settings. Once your child starts to feel comfortable with a given setting, go ahead and move a click up. The clutch on these dirt bikes can be a little tricky at first but soon you will be making adjustments in minutes. Tuning the clutch to fit your child’s needs will increase their confidence at the track and lead to faster lap times and more enjoyable ride days.