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Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Call us at: 0433 880 748
Free shipping over $200 (excludes tyres and bulky items)
Need help? book@xpertmotogear.com.au
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- ➔ Engine rebuild kits (1447 products)
The Vertex Top End Rebuild Kit (V24370B) is engineered to restore the engine of the Yamaha YZ85 to factory-specification performance, covering model years 2019 through 2025. Vertex is an Italian manufacturer with a long-standing reputation for precision-machined piston and engine components used in competitive motocross.
Sized at 47.46mm bore, this kit is suited to riders undertaking a scheduled top end service on their YZ85. Having the correct components on hand before splitting the top end simplifies the rebuild and minimises downtime between rides.
- Specific fitment: Yamaha YZ85 model years 2019–2025
- 47.46mm bore diameter
- Vertex part number V24370B
- Manufactured by Vertex, a specialist in precision motocross engine components
| Brand | Vertex |
|---|---|
| Part Number | V24370B |
| SKU | VK2066B |
| Bore Size | 47.46mm |
| Fitment | Yamaha YZ85 2019–2025 |
| Engine Type | 2-stroke |
- Before fitting, measure the cylinder bore with a bore gauge to confirm the 47.46mm kit is the correct size for your cylinder's current condition.
- Consult the Yamaha YZ85 factory service manual for the correct piston-to-wall clearance, torque figures, and assembly sequence before beginning the rebuild.
- Lightly coat the piston skirt, rings, wrist pin, and cylinder bore with fresh 2-stroke engine oil prior to assembly to prevent dry-start damage.
- Ensure ring end gaps are correctly positioned as specified in the service manual before sliding the piston into the bore.
- Replace the cylinder head gasket and base gasket at the same time as the top end rebuild; do not reuse compressed gaskets.
- After reassembly, run a gentle break-in procedure — avoid sustained high-RPM operation for the first few heat cycles to allow rings to seat correctly.
- Inspect the powervalve (YPVS) and clean any carbon deposits from the exhaust port while the top end is apart.
- Dispose of used components (old piston, rings, gaskets) appropriately; do not reuse worn rings or a stretched wrist pin.
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