He passed his A2 in the spring, spent three weeks looking, and bought a big naked bike that had been professionally restricted to 35 kW with a dealer-fitted kit and paperwork to prove it. The restriction was genuine. The certificate was genuine. The bike was still not legal for him to ride.

The machine had made a little over 90 kW before it was restricted, and the A2 rules do not only cap what a bike produces. They also cap what it produced originally. A bike making more than double the A2 limit before restriction is outside the category however well the restriction is done.

He found out at a roadside stop, which is the expensive way.

First, the question everyone asks

What is the cc limit on A2?

There isn't one.

A2 does not cap engine capacity anywhere. It caps power, and power relative to weight, and what the bike produced before anyone restricted it. Capacity only matters through its effect on those.

Which is why the answer to "can I ride a 650 on A2" is sometimes yes and sometimes no, depending entirely on the model. Some 500s are outside the category. Plenty of 650s and a few 900s are inside it. Asking about cc will not get you a reliable answer, and a seller who answers in cc is guessing.

The three limits

The law is written in kilowatts, which is why every official source quotes 35 kW. Road tests, forums and dealers talk in bhp. They are the same limit in different units.

One trap worth knowing. Manufacturer specifications often quote PS rather than bhp, and they are not the same. A bike listed at 47 PS is about 46 bhp and comfortably legal. A bike listed at 47 bhp is sitting right on the limit. Check which unit a specification is using before you rely on it.

The 70 kW rule, and why it catches people

This is the one that costs riders money, because it is counter-intuitive.

You would reasonably assume that a bike restricted to 35 kW is a 35 kW bike. Legally it is not. The category asks two questions: what does it make now, and what did it make before anyone touched it. Fail the second and the restriction is irrelevant.

A 70 kW bike restricted to 35 kW is fine. Halved exactly, which is the limit.

A 90 kW bike restricted to 35 kW is not. It started above double, so no restriction brings it into the category.

A bike built at 35 kW or below needs nothing. Plenty of mid-capacity machines leave the factory A2-compliant.

The practical consequence is that when you are shopping, the restriction kit tells you nothing on its own. You need the original power figure for that model and variant. A dealer who says "it's restricted, you're fine" may be entirely sincere and entirely wrong.

The power-to-weight limit

The second limit trips up a different set of bikes: light ones.

At 0.2 kW/kg, a bike weighing 175 kg may produce up to 35 kW. A bike weighing 150 kg may produce up to 30 kW, and the 35 kW cap becomes irrelevant because the weight limit bites first.

Weight here means the machine's kerb weight as registered rather than a dry figure from a brochure. Manufacturers quote dry weights that exclude fluids and sometimes the battery, and using one will give you a number that flatters the bike and misleads you.

Getting the licence

1. CBT.
2. Motorcycle theory test.
3. Module 1, off road.
4. Module 2, on road.

Both practical modules are taken on a machine of at least 245cc producing between 20 and 35 kW, which is the DVSA minimum for an A2 test bike. Minimum age is 19. You may take A2 with no prior motorcycle licence, or as a progression from A1.

What you can ride

More than people expect, which is the good news after the warning at the top.

Plenty of mid-capacity machines are built A2-compliant from the factory: parallel twins, single-cylinder bikes and a good number of adventure-styled machines around the middle of the range. Those need no restriction, no kit, and no argument at a roadside stop.

Beyond those, a large number of bikes are offered with manufacturer-approved restriction kits, and provided the unrestricted figure sits at or under 70 kW they are legitimately A2 machines.

What is out of reach is the top of the market. Litre sportsbikes, big adventure bikes and most large-capacity nakeds start too far above 70 kW for any restriction to help.

Moving up to full A

Two routes.

Progressive access at 21, after holding A2 for two years, by taking the tests again on a bike meeting the full A specification.

Direct access at 24, which requires no prior motorcycle licence at all.

If you are 22 and holding A2, waiting until 24 is often simpler than progressive access at 21, because the route to direct access is the same either way and you skip a set of fees.

The DVSA consultation that ran from January to May 2026 proposed allowing progression through a training course rather than repeat testing. Nothing has changed yet.

When you sell the restricted bike

Worth thinking about at the point you buy it.

A restricted bike with the original parts kept and included sells to both markets: A2 riders who want it restricted, and full-licence riders who will remove the kit. A restricted bike whose original components have gone sells only to the first group, and it is worth less as a result.

FAQs

Can any bike be restricted to A2?

No. If it made more than 70 kW originally, no restriction brings it into the category however well it is done.

Does A2 limit engine size?

No. There is no cc limit. The limits are power, power-to-weight and original power. Capacity only matters through its effect on those.

What is the biggest cc bike I can ride on A2?

There is no maximum. Some 900s are A2-legal and some 500s are not, because it depends on power output and weight rather than capacity. Run the specific model through the calculator rather than working from engine size.

Is 47bhp the A2 limit?

Effectively yes. The legal figure is 35 kW, which works out at a shade under 47 bhp. Watch for specifications quoted in PS, which is a different unit and slightly more generous.

What happens if I ride a bike outside A2?

You are riding without the correct licence entitlement for that machine, which generally means your insurance is not valid either. It is a considerably larger problem than a licensing technicality.