Hi guys, I recently wanted to change to a pair of Dr Pulley rollers (sliders) on my X-Max 300, the amount of information out there on how to do this was fairly scarce so I thought I'd make a short guide while it's still fresh in my head. Maybe it will help someone. This is for the X-MAX 300 but there will obviously be similarities between a lot of scooters. The X-Max 300 uses six 23x18 17g rollers. The engine delivers max torque at 5750rpm and max hp at 7250rpm. So for max performance you want to get as close as possible to 7250 during acceleration, if max performance is your goal that is. My goal was different however, I was more than happy with the original acceleration of the X-Max 300 and instead I wanted to bring the rpm down while cruising at around 60mph from around 5800 rpm to something a bit closer to 5000rpm. To do this I replaced the original 17g rollers with 23g Dr Pulley sliders. This is not what Dr Pulley recommends but it was what I wanted. The engine is now much more relaxed while cruising and while in town the rpm rarely goes above 6000rpm even with full throttle. This means I'm now happy to give it more throttle more of the time, similar to short shifting. The driving experience is now closer to the X-Max 400 engine characteristic, it feels more like a 400-500 cc scooter now than a 300 cc scooter actually. The engine is more relaxed, but still fast. Maybe I lost 1 second or so in 0-60 time but personally I don't care, this suite my driving style better. So on with the guide then. Step1: Tools needed: Pulley holding tool ($12 on ebay, had to be modified slightly to open wider but otherwise good), medium size screwdriver, 8mm socket, 10mm socket, 17mm socket, 1/2 socket wrench, socket wrench extension. Recommended: 1/2 Breaker bar, small rope, towel. Step2: Remove upper air filter cover for access (lots of screws and two bolts) Step3: Remove lower cover for access and secure airbox with rope to get it out of the way Step4: Remove transmission ventilation duct for access Step5: Remove transmission cover (loosen all bolts and tap gently around the cover, then wiggle it straight out) Step6: Prepare to remove the primary sheave bolt like so. This will be a tight sucker and breaker bar is recommended. Remember to push down with your left palm on the 90 degree bend and pull up with your right hand on the handle. You want a rotating torque on the sheave bolt and little to no force up or down. Step7: Remove the primary sheave bolt Step8: Remove the primary sheave and then pinch and fold away the belt like so. Step9: Remove the variator unit by pinching it and pulling it out Step10: Take note of the orientation, it might not matter but just in case. Step11: Open and carefully clean all surfaces then replace rollers / sliders. Step12: Correct slider orientation for Dr Pulley. Step13: Put the cover back and then while pinching and holding the variator unit together put it back in the scooter. IMPORTANT!! Hold the unit together to prevent the sliders from falling into a strange position while putting it back. Avoid getting any kind of grease on the sheave surfaces. Step14: Put the belt back. I recommend putting something between the belt and the primary axle, like so. It will make it easier to get the primary sheave on. Step15: Put the primary sheave back on (it will only go in one way I believe) and prepare to tighten everything up again, this might be the one part of the job which requires some "feeling". I haven't been able to find a service manual, or someone who knows how tight this bolt should be, but the recommended torque for the X-Max 250 primary sheave bolt was 80 Nm. So I would guesstimate that if you torque this bolt to about 80-100Nm it should be in the ballbark. Suffice to say this bolt is one you want really tight, as tight as a wheel nut. 100-130Nm is not an uncommon recommendation for wheel nuts so that can serve as a some guide. If you don't have a torque wrench I recommend that you took note of how hard the bolt was when you loosened it. I tightened the bolt as hard as I could make it with my "small" socket wrench below and then a little bit more with the breaker bar. If the scooter starts tipping backwards while on the center stand you should be in a decent spot. I would also recommend that you tighten the bolt a little, the rotate the entire assembly a couple of turns to make the belt move out of the way and then tighten it some more. If you're nervous about this part a basic torque wrench is about $20 on ebay, just make sure it does the torque range required. If anyone finds out the exact torque recommendation for the X-Max 300 let us know and we can update the text. Step 16: Everything back together, check that all looks ok, rotate it around a couple of times, no parts forgotten inside, no grease on sheave or belt etc. Step17: Put everything back together in the reverse order. Take note of the ABS sensor wire and also final transmission air hose, as below. Hope you enjoyed my little guide, personally I was very happy with the result of this modification for my driving style and my X-MAX 300 now has a more "grown up" and relaxed character, but still fast. If you want max performance probably go with 15-16g sliders, but it will be "buzzy". If you want relaxed go with 22-24g sliders. If you want somewhere in between... well you get the idea.