How do you know 133 km/h is its top speed? If that's the manufacturers claim, then know they always exaggerate horsepower or top speed figures. They don't lie, they just use the figures from perfectly tuned machines running at sea level under optimum temperature and humidity conditions. The higher elevation you're at, the higher the ambient temperature and the higher the humidity , the less power an engine is going to make no matter what you do.
If that's the claim of your friends or someone else, know that many people have a tendency to embellish the facts because they think it makes them look cooler than everyone else.
In addition, speedometers are often inaccurate and if cable driven from the front wheel, putting a smaller front tire will spin the speedo faster, falsely indicating a higher speed. If driven from a pulse generator in the tranny, changing the rear tire size or sprockets will give a false reading.
If your bike actually should go faster, then make sure the air filter is clean and free flowing (old paper ones can look clean but still be restrictive), the spark plug is new and that the throttle is actually opening the carb slide or butterfly all the way. When miss-adjusted, you're never giving it all you should. That's what the threaded adjusters on the ends of the throttle cables are for.
