Our verdict
Discontinued but still working all over the country. Cricket clubs, schools, and head gardeners run G21s with 4000+ hours on them and no end in sight. Buy on hours and service history, not year, and this is the cheapest way into proper Kubota diesel groundskeeping.
Pros & cons
Pros
- Direct predecessor to the G23, same Kubota D722 diesel
- HD body and reinforced collector for daily commercial work
- Parts shared with the current G-series, still well supported
- Used examples are a third of the price of a current G26
Cons
- Discontinued, no factory warranty on a used unit
- Older 3-cylinder lacks the cleaner emissions of the D902
- Heavy at 460kg, needs proper barn or trailer storage
Full specs
| Type | Ride-on |
|---|---|
| Cut width | 122 cm |
| Engine / Power | Kubota D722 diesel 3-cylinder |
| Weight | 460 kg |
| Deck | Steel |
| Self-propelled | Yes |
| Rear roller | No |
| Mulching | Yes |
| Cutting heights | 6 positions |
| Bag capacity | 500 L |
| Suited to lawn | Large |
| Noise level | 100 dB |
Buying second-hand
£4500-9000 used depending on hours. Under 1500 hours is excellent for any G21, 3000-4000 is normal and fine if serviced. Always confirm the deck spindles spin freely without grinding, replacement is a five-figure job on the older G-series. Diesel injector spray pattern matters, ask for a recent compression test on anything over 2500 hours.
Where to buy the Kubota G21-II HD
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Repair-cost reference
UK 2026 ballpark prices for the parts you're most likely to need on this mower. OEM is dealer-genuine; aftermarket is what you'll find on eBay or generic small-engine suppliers. Use these to sense-check any quote and to negotiate on used buys.
| Part / job | OEM | Aftermarket |
|---|---|---|
|
Replacement 122cm blade
Annual sharpening is free; replace when bent or cracked.
|
£24–£32 | £8–£12 |
|
Oil filter
|
£15 | £8 |
|
Fuel filter
|
£25 | £12 |
|
Air filter element
|
£35 | £18 |
|
Deck spindle bearing
Replace if blade vibrates or the deck whines under load.
|
£48 each | £22 each |
|
Transaxle service (gear oil change)
Hydrostatic units need fresh fluid every 200 hours.
|
£60 dealer | £15 DIY |
|
12V starter battery
Generic 12V 18Ah lawn-tractor battery — fits most ride-ons.
|
£45 | £28 |
Fair-offer calculator
Tell us about a specific used listing for the Kubota G21-II HD you're looking at. We'll compute a fair offer range from our used-market data and the condition signals you provide.
Calculations are guidance, not gospel. Used-market prices vary by region (Scotland is typically 10–15% cheaper than the South-East), season (October cheapest, March most expensive), and seller motivation.
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