In Europe there is limit to the kW output of motorcycles someone with a learners permit can drive, so in a lot of cases the output of a more powerful bike is limited so they can learn on the same bike to what they will be driving.
To achieve this on some bikes you can restrict the air flow through the carburettor, which can be as simple as adding a piece of cardboard in the right place...
A few years ago the EU introduced a change/addendum to the A2 class restriction barring holders of that license class from driving bikes that were too limited in order to get their vehicle certification:
Motorcycles of a power not exceeding 35 kilowatts (47 hp) and with a power/weight ratio not exceeding 0.2 kilowatts per kilogram (0.12 hp/lb)
and not derived from a vehicle of more than double its power.
My very first bike, and those of all my friends who rode, was the same. The process (called derestricting) usually involved removing a cross feed pipe between the exhaust and the intake.
In Europe there is limit to the kW output of motorcycles someone with a learners permit can drive, so in a lot of cases the output of a more powerful bike is limited so they can learn on the same bike to what they will be driving.
To achieve this on some bikes you can restrict the air flow through the carburettor, which can be as simple as adding a piece of cardboard in the right place...