Qianjiang — the parent company behind QJMotor and Benelli — just had a US patent published for an engine that looks like a V-twin, sounds like it should be a V-twin, and is, underneath all that, a single. I’ve read this filing three times now instead of doing actual work, so let’s get into it.

What the patent actually shows

The filing, published by the USPTO on 27 August 2026, describes a single-cylinder engine built inside a crankcase cast in the shape of an 80-degree V-twin — the same layout as Qianjiang’s existing 997cc Morbidelli/MBP V-twin. Only one of the two cylinder bores does any actual work. The other houses a second piston, connected to the same crankshaft via its own connecting rod, that never sees a spark or a fuel charge — it exists purely as a moving counterweight. That dummy piston has a vent hole running straight through it, top face to bottom, so it never compresses the air trapped above it, and the dummy cylinder itself is bored noticeably smaller than the real one.

The point is smoothness on the cheap. A single-cylinder engine vibrates in ways a proper multi-cylinder doesn’t, and the usual fix — a geared balance shaft — adds cost and complexity. Qianjiang’s version gets a similar damping effect by reusing crankcase tooling and casting architecture it already has set up for its V-twin production, rather than engineering a separate balance-shaft assembly from scratch.

An old idea, tried again

If this sounds familiar, it should: it’s the same basic approach Ducati’s Massimo Bordi tried — and then abandoned — while developing the 1993 Supermono, which also used an inert dummy piston purely as a balancing mass rather than a geared shaft. Ducati moved on from it decades ago. Qianjiang, working from a very different cost base and a very different target market, is having another go.

The filing traces back further than the August publication date suggests: the underlying design was first filed in China back in August 2022, followed by a PCT international application the following year, before this specific US document was filed and finally published this week.

What we know / What’s still unclear

What we know: - The US patent was published 27 August 2026, describing a single-cylinder engine in a V-twin-shaped crankcase with a vented dummy piston as the balancing mass. - The design traces back to an original Chinese filing in August 2022, followed by a PCT application in 2023. - The V-angle (80 degrees) and general architecture match Qianjiang’s existing 997cc V-twin, meaning the same tooling could plausibly be reused.

What’s still unclear: - Whether this design will ever reach a production QJMotor or Benelli model, or stays a patent-shelf curiosity — nothing in the filing or Qianjiang’s public statements confirms a specific bike. - Displacement, projected power output, and target market (small-capacity commuter engine vs. a performance single) aren’t specified in the patent itself. - Whether it would be built and sold in Europe, where QJMotor and Benelli both already have a dealer network, or stay China/Asia-market only.

FAQ

What is Qianjiang’s new patent actually for?

A single-cylinder motorcycle engine built inside a crankcase shaped like a V-twin, where the “second cylinder” holds an inert, vented dummy piston that only acts as a counterbalance — it never fires.

Why build a single disguised as a V-twin?

Cost. Reusing V-twin crankcase tooling that already exists is cheaper than engineering a separate geared balance-shaft system, while still smoothing out the vibration a plain single would otherwise have.

Has anyone tried this before?

Yes — Ducati’s Massimo Bordi used a nearly identical dummy-piston balancing approach during early development of the 1993 Supermono, before abandoning it for later designs.

Is this engine going into a production motorcycle?

Unknown. The patent doesn’t name a specific model, and Qianjiang hasn’t confirmed one publicly. The design could end up in a future QJMotor or Benelli engine, or go no further than the patent office.

Qianjiang isn’t the only Chinese-owned manufacturer working engine tricks into an unusually crowded small-and-midsize segment — Kove’s own 660X emerged the same way, via leaked homologation paperwork rather than an official reveal, before Kove confirmed it themselves. And if you want a reminder of how differently a legacy European brand handles the same “reveal an unbuilt engine via a filing” moment, Ducati’s own CARB paperwork just outed a 2027 Panigale V4 SP months ahead of any announcement.

Reporting via: motorcyclenews.com, cycleworld.com, rideapart.com