My lifan 125cc is spluttering threw the gears n isnt accelerating properly

No. However it most likely has a rev-limiter to prevent overrevving/damage.

1. Worn clutch: If the clutch is worn, it may not be disengaging properly when you change gears, causing the engine to continue to rev as if you were still accelerating. This can also cause difficulty shifting gears or a slipping feeling when accelerating.
2. Dirty or faulty throttle body: The throttle body controls the amount of air entering the engine and adjusts the idle speed. If it's dirty or faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.
3. Vacuum leak: A vacuum leak can cause the engine to rev excessively or idle roughly. The leak can be caused by a cracked or disconnected vacuum hose, or a malfunctioning intake manifold gasket.
4. Faulty idle air control valve: The idle air control valve regulates the engine's idle speed. If it's faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.

The carb is flowing over, check the needle valve in the carb floater.

may do but I think that it is in the carby
probably an accelerator pump jets blocked or failing to work properly
a carby overhaul may be in order

Check your vacuum lines. May have a lean misfire.

Regular unleded

Hello i have a Lifan Mirage 125cc 4 stroke does anyone know how to de restrict them at all many thanks

Bradley

air filter is clogged or you need to clean the carb make sure you have good carb compression and that your gas is running threw the lines properly

Unless you find a small "restricting washer" between the head and the exhaust pipe...Then usually there is no easy means. In the past these "washers" were put in place to reduce performance, the idea was as the riders skills improve the washer can be removed. It also was a way for parents to keep their children from zooming flat out everywhere.

check the tire pressure to ensure proper psi all around as well as the brakes may be more tense on one side than the other a checking and replacement or bleeding of the brake system is suggested to start with