hi there , i have a 2004 gilera dna 125 , bought it off a mate ... wont start just makes a wierd noise when using electric start ... been told its a seized engine ... need to know what to do to fix it and if any parts what parts i need to buy ?

johny p, February 2010

I have a gilera runner 125cc and engine has blown up, how do i fix it?

g, April 2013

unfortunatley these 4 valve 'leader' engines drop valves so i expect that is what has happened.the collets drop outat high revs and the valve ounches itself through the pistion and wrecks the top end and sometimes batters the top of the con rod.take the plug out and have a look at the end of it it usually smashes the end to a pulp.the downfall of the 4 valve engine is this the 2 valve leader engines are bullet proof but a little less powerful.its worth the power loss for reliabilty but gilera insist on putting the four valv head on the vx runners and dna's.apart form the 50cc dna thats a 2 stroke.

adam bike doctor, February 2010

Ok. First thing first is it a two stroke or the later four stroke. I am guessing its a 2 stroke.
If it is a two stroke it could of siezed in several places
1 the piston and rings which has proabably damaged your bore and so will need a rebore. You will need a new piston set and a rebore. Top end strip down as long as you know what your doing then its not a terrible
2. bearing on the crank. If this is the case then its a much bigger job, split the engine and a strip down. Bit of a job.

bb, February 2010