President AL series: Quadcut blade disc torque and blade change
| Bulletin number | SB-2026-04 |
|---|---|
| Issued | 12 March 2026 · supersedes SB-2025-07 |
| Models affected | President 1500 AL 3'n1 (561751), President 2000 AL S18 (565877), 800 AL S21 SPV (564897), all serial numbers |
| Classification | Service procedure. This is not a safety notice. Warranty applies only inside the machine's coverage window. |
Symptom
Vibration through the handlebar at full throttle, a rattle from the deck on shutdown, or a blade disc that has worked loose within 20 to 40 hours of a blade change. In most reported cases the disc centre bolt was re-used and torqued dry, or the four blade bolts were tightened in sequence instead of in a cross pattern.
Cause
The Quadcut system carries four short blades on a cast disc rather than one long bar blade. The disc is clamped to the crankshaft by a single centre bolt through a friction washer, and the blades are held by four bolts around the disc. The centre bolt is a stretch fastener: once it has been torqued it must not be re-used. A re-used bolt loses roughly a quarter of its clamp load, which lets the disc creep on the crankshaft taper and shows up as vibration long before anything fails.
Procedure
- Park on level ground, stop the engine, let it cool, remove the spark plug lead and, on 60V machines, remove the battery pack.
- Tip the machine on its side with the air filter and carburettor uppermost so fuel cannot run into the cylinder.
- Block the disc with a timber offcut against the deck skirt. Do not block against the blades.
- Remove the four blade bolts, then the disc centre bolt. Discard the centre bolt. It is a single-use stretch fastener.
- Clean the crankshaft taper and the disc bore. Inspect the friction washer: any scoring, blueing or flattening of the tangs means replacement.
- Inspect the disc for cracks radiating from the blade bolt holes. A cracked disc is scrap, not a weld repair.
- Fit the disc dry, fit a new centre bolt and torque it to 45 Nm (33 lb ft).
- Fit the four blades so the lifting wing on each blade faces the deck, then torque the four blade bolts to 20 Nm (15 lb ft) in a cross pattern, then repeat the cross pattern a second time.
- Rotate the disc by hand through two full turns and confirm that no blade touches the deck skirt.
- Stand the machine up, refit the plug lead or the battery, and run at full throttle for two minutes. Residual vibration after two minutes means an unbalanced blade set: replace all four blades as a set, never singly.
Parts
- Quadcut blade set (four blades, supplied as a matched set) and disc centre bolt kit, ordered per model from Parts & accessories.
- Model pages and exploded views: Masport equipment.
Labour and warranty coding
Flat-rate allowance 0.4 h for the inspection and re-torque, 0.6 h when the blade set is replaced. Blades and the friction washer are wear items covered for 30 days from the date of sale; outside that window this is a customer-pay repair. A cracked disc inside the parts coverage period is a warranty part. Open the claim from Warranty claims and quote SB-2026-04 in the fault description.