I snapped my drive belt on gilera runner vx 125, how do i change?

Eww. Umm. Try to put it back together best you can and try to get another key made. Or you could just hotwire it every time.

rear wheel bearings are worn out replace or out of balanced rear tire

can gilera vx runner 125 immobiliser be by passed 4 stroke

If it is a mono shock it is easy but with shocks it just takes a little more time. Take your time

u are better off replacing the whole engine bec in my exsperince u will spend around £200 pound fixing that u could pick up a another gilera runner engine for £150-£200 from ebay etc

have you checked ht lead from the spark plug as this may have jumped off

if the engine is dieing, check that the spark plug has a cap that is sealed eg rubber boot around it.
if the revs are still there but the bike slows the trans belt is getting water in it check the trans gasket for sealing.

Its the really big bolt on the right hand side