Gilera DNA 125 not starting problem 

Try some Easy Start, works a treat

do you know if there is no spark? take the plug out, connect it to the boot, and turn the engine over. see if theres a spark. preferably when its dusk. do you know if fuel is getting to the carburettor? have you taken the carburettor out and given it a clean? have you also checked the throttle idle screw as well?

try checking ECU, immobilizer, or key recognition. common problems with gilera 4 strokes.

Thats because its to cold!

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