Rear CV Boot Inspection and Replacement on the 2018 Kymco Mxu 150X
Shop parts for a 2018 Kymco Mxu 150X ATV.
Why CV Boots Fail on the Mxu 150X
The CV boot on the 2018 Kymco Mxu 150X protects the rear axle CV joint from the contamination and grease loss that lead to joint failure. On a utility ATV used for hauling, plowing, or trail work, the boot faces more demanding conditions than a recreational machine would see in equivalent operating hours. Deep mud crossings coat the boot exterior with abrasive material, water submersion tests the clamp seals, and sustained low-speed torque loads during work use cycle the boot continuously through its flexing range. The boot must maintain a sealed environment for the CV grease packed inside the joint through all of these conditions.
Age and UV exposure are the most consistent failure causes on the Mxu 150X. The rubber compound hardens over time, losing the flexibility it needs to flex at the fold lines without cracking. A boot that appears intact on a visual check may be brittle enough at the folds to crack during a cold-morning ride when rubber stiffens in low temperatures. Physical damage from trail debris is equally common on a utility machine—the inner boot at the differential end of the rear axle sits close to the ground and is directly in the path of anything the rear wheels kick up during field or trail work.
As a 2WD utility ATV, the Mxu 150X drives only the rear wheels. The CV boots are located on the rear axle only—the front wheels steer and roll freely without a driven axle, so this service is rear-focused.
Signs of a Failing Rear CV Boot
The clearest evidence of a torn CV boot on the 2018 Kymco Mxu 150X is grease deposited on a surface near the rear axle. Once a boot tears, the rotating axle slings CV grease onto the inner face of the rear wheel, the brake rotor or drum, the caliper, or the frame rail adjacent to the axle. CV grease is thick, dark, and adhesive—it coats surfaces differently than mud or brake dust and accumulates with each ride. Finding this on the Mxu 150X near the rear axle is enough to stop work and inspect before continuing.
A hands-on inspection with the wheel removed confirms the damage location and extent. Raise the Mxu 150X on jack stands, remove the wheel, and work each boot by hand while rotating the axle. Feel and look for any tear, crack, puncture, or gap at a clamp edge. The fold lines and clamp transition zones are the highest-stress areas. A boot that shows surface crazing or feels hard and inflexible at the folds should be replaced proactively. A clicking or popping from the rear axle during acceleration or tight turns indicates joint wear has begun—the inspection needs to evaluate the joint at that point, not just the boot.
On the Mxu 150X, CV boot service is rear-axle work. The front wheels are not driven and have no CV joints to service on this machine.
Tools and Parts for the Replacement
A rear CV boot replacement on the 2018 Kymco Mxu 150X requires: a floor jack and two jack stands; an axle nut socket in the correct size for the Mxu 150X; a torque wrench; snap-ring pliers for the differential-end retaining clip; boot clamp pliers or an ear-crimp tool; and shop rags. The CV boot kit must include the replacement boot, both clamp bands, and the correct CV grease. CV joints operate under high contact pressure between their precision bearing balls and races, and they require a molybdenum-based compound to maintain adequate film strength at those loads. Using a substitute grease type reduces protection and shortens joint service life.
Set a drain pan under the axle area before starting. Old contaminated grease from a torn boot needs to come out of the joint completely before new grease goes in. MotoSport.com stocks CV boot kits and axle assemblies for the Mxu 150X.
Removing the Axle and Damaged Boot
Raise the 2018 Kymco Mxu 150X on jack stands and remove the rear wheel on the affected side. Remove the cotter pin and axle nut. Push the axle spline inward to separate it from the hub—use a hub puller if the Mxu 150X has a tight spline fit. At the inboard end, compress the snap ring at the differential housing with snap-ring pliers and pull the axle free. Lay it on a clean surface, cut both clamp bands, and slide the damaged boot off the shaft. Clean the clamp groove areas on both the axle shaft and differential housing before installing the replacement boot on the Mxu 150X.
Checking the CV Joint While Exposed
With the boot off the 2018 Kymco Mxu 150X, clean old grease from the CV joint and articulate it through its full designed range—compression and extension along the shaft plus full angular rotation. Smooth, even motion through the entire range indicates a serviceable joint. Roughness or grinding at any point in the articulation means bearing wear that repacking won’t fix. Hold the shaft and push the outer housing in non-articulating directions to check for play. Any clunking or excess movement outside the designed articulation range on the Mxu 150X means the axle needs replacement, not just a new boot.
Cleaning, Packing, and Installing the New Boot
Clean the CV joint completely on the 2018 Kymco Mxu 150X—housing, bearing balls, and inner race free of all old grease and contamination. Slide the new boot onto the shaft before reconnecting the joint end. Pack the CV grease from the Mxu 150X’s kit into the joint by hand, filling the bearing pockets and rotating the housing for even distribution. Use the full quantity. Seat the new boot with both ends in the clamp grooves, crimp both clamps fully, and verify neither rotates. MotoSport.com stocks CV boot kits for this ATV.
Reinstallation and Final Verification
Push the inboard axle end into the differential on the 2018 Kymco Mxu 150X until the snap ring seats positively. A hand-pull should confirm it’s locked. Guide the outboard spline into the hub, install the axle nut, and torque to the Mxu 150X’s specification. Secure with a new cotter pin or re-stake the nut as appropriate. Reinstall the wheel and torque the lug nuts. Lower the Mxu 150X and cycle the rear suspension through its range to check for boot clearance. A brief low-speed test confirms the repair is complete. MotoSport.com stocks CV boot kits and axle assemblies for this ATV.
Related Shopping Categories
Shop CV Joints for a 2018 Kymco Mxu 150X ATV.
Shop Axles for a 2018 Kymco Mxu 150X ATV.
Shop Lubricants & Solvents for a 2018 Kymco Mxu 150X ATV.
Shop Wheel Bearings for a 2018 Kymco Mxu 150X ATV.
Shop Skid Plates for a 2018 Kymco Mxu 150X ATV.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your ATV's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.