My gilera runner 125st 2008 when started and throttle is pulled back it just dies the power goes

SOURCE: misfiring at speed on gilera 200 scooter

This sounds more like a lean fuel condition than ignition. If it was stored over the winter without the gas being drained or a fuel stabilizer being added, you'll likely have varnish build-up in the fuel system that is not allowing sufficient fuel flow.  If your engine is fuel injected, it's likely your injector is partially clogged.  If it's carbureted, your carb jets may be partially clogged or your carb float may be sticking and not allowing the needle valve to fully open.  Fill the gas tank with fresh gasoline, but leave enough room for a can of Sea Foam.  The Sea Foam may be able to break up the deposits and allow fuel to flow again.  However, there's no guarantee and the fuel system may have to be disassembled to be cleaned.

SOURCE: gear box oil my bike cuts out at top speeds

the gear box oil does not go anywhere.it helps to lubricate the gear surface.its located at the rear .pls check your carb and spark plug.if two item is o.k check your engine block is there any crack at your engine

SOURCE: hi i have a gilera runner vx 125cc 4 stroke

Replace spark plug Add some sea foam to fuel it is a fuel cleaner See if that helps you MOPAR KENNY

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SOURCE: just got a gilera runner that been converted to

Sounds like the carb. is to small.
Or you can try changing the main jet to a larger size first

SOURCE: Hi I have a gilera runner st 2006. The bike starts

Check the spark plug or fuel filter, or you might have a little water in the gas use dry gas in your tank