A Honda BeAT CVT vibration is most obvious when pulling away, but the source can be the clutch, the belt, the rollers, the variator faces or an engine mount. Replacing the belt alone is the most common way to spend money and keep the judder.
Before you start
The CVT contains a strong spring and sharp edges. Do not open the case with the engine running, do not put fingers near the belt, and do not reuse a damaged belt. If the scooter vibrates so much that it feels unstable, stop riding and have it recovered.
Machine file Honda BeAT 110
- Engine
- Air-cooled SOHC single
- Cooling
- Air
- Fuel
- PGM-FI
- Transmission
- CVT
- Final drive
- V-belt
Describe the vibration before opening the case
Does it happen only as the clutch engages, at a steady 30 km/h, or when accelerating hard? A judder at take-off that disappears once the scooter is moving points to the clutch or the belt. A vibration that follows road speed rather than engine speed points to a wheel, tyre or bearing.
A vibration that follows engine speed in neutral points to the engine or mounts. That distinction matters because the CVT case is not the first place to look for every shake.
Vibration pattern and likely source
| Pattern | Likely source | Check |
|---|---|---|
| Judder only as it pulls away | Clutch shoes or bell | Glaze, scoring, spring tension |
| Shudder at small throttle | Rollers or sliders | Flat spots and free movement |
| Chirp or squeal on acceleration | Belt edge or dry bearing | Belt width, bearing play |
| Vibration follows road speed | Wheel, tyre or bearing | Balance, pressure, play |
| Shake at idle in neutral | Engine mount or exhaust | Mount bolts and hangers |
Clutch shoes and the bell
The centrifugal clutch engages as engine speed rises. Glazed shoes, a scored bell, weak springs or dust in the housing make that engagement uneven. The rider feels a shudder, sometimes a chirp, and the scooter may creep or snatch when the throttle is barely open.
The bell and shoes must be inspected together. A new set of shoes on a scored bell will not seat properly, and a new bell with glazed shoes will glaze again. Cleaning the housing and checking for oil from the input seal is part of the job.
Belt, rollers and variator faces
The belt transfers drive and changes ratio as the variator closes and opens. A belt that has lost width, has a tight spot or a damaged edge can vibrate. Flat spots on the rollers or worn sliders make the variator move unevenly, especially at small throttle openings.
Inspect the variator faces for grooves and the rollers for flat spots. A roller that no longer rolls will wear a flat and the vibration will return. Replace the belt, rollers and sliders as a set when they are worn together.
Contamination and seals
Oil or grease inside the CVT case is a separate fault. It can come from the crankshaft seal, the input shaft seal or from too much grease on a bearing. Contamination makes the belt slip and the clutch grab, and it will ruin new parts.
Clean the case, replace the seal and then fit the new belt. If the case is oily again after a few hundred kilometres, the seal was not the source. Do not solve an oil leak with a new belt.
Engine mounts and exhaust
A worn engine mount or a loose exhaust bracket can produce a shake that feels like CVT judder. The BeAT's small engine moves under load; if a mount is soft or a bolt is loose, the movement is transmitted to the frame. Check the mount bolts and the exhaust hangers before condemning the CVT.
A loose centre stand or a cracked body panel can also buzz at a particular engine speed. Ask a helper to hold the scooter steady while you listen with the engine idling. Do not put hands near the belt or fan with the engine running.
Repair options and the test ride
A workshop will measure the belt width, inspect the variator and clutch, and check the seals. The repair may be a clean and a set of rollers, or a belt and clutch service. The right answer depends on the measured wear, not on the mileage alone.
After the repair, test the scooter from a stop on a quiet road. The engagement should be smooth, the engine speed should rise and fall without a step, and there should be no chirp. If the judder remains, go back with the exact conditions rather than accepting a second guess.
Keeping it from coming back
Smooth, progressive throttle openings are gentler on the clutch shoes than repeated hard launches, and they cost nothing. Clean the CVT case and its vents so dust and water can escape, and have the belt width, rollers and clutch bell inspected together rather than one at a time. A squeal or judder that returns after a belt change means the bell or the shoes were not measured.
A short checklist
- Note whether the vibration follows engine speed or road speed.
- Check tyre pressure and wheel balance before opening the CVT.
- Inspect the belt for width loss, cracks and glazing.
- Check rollers and sliders for flat spots and free movement.
- Inspect the clutch shoes and bell for glaze and scoring.
- Look for oil or grease inside the case before fitting new parts.
Questions owners ask
Does a BeAT CVT vibration always mean a new belt?
No. The belt is one wear item among several. A glazed clutch, flat rollers, worn sliders, a scored variator or an engine mount can produce the same complaint. The belt should be measured, not replaced by default.
Can I ride with a juddering CVT?
A light judder at take-off is a reason to book an inspection. A vibration that makes the scooter unstable, a smell of burning rubber or a belt that is clearly damaged is a reason to stop riding.
Why does the judder come back after a repair?
The most common reasons are a reused worn part, a scored bell or variator, contamination from a leaking seal, or a mount that was not checked. Go back with the conditions and ask which parts were measured.
