*Please help* Malossi 70cc piston seizure..

Got my speedfight a few weeks ago, last week the engine seized on the way to school, when i took it apart the piston was completely fucked, first i saw there were lots of dents at the top off the piston and the head of the engine i thought a tiny rock somehow got in my engine because a few days prior my air filter came of and was lost so i had to rid it home very slowly without on on at all, but then i got on but it wasn't the exact same one.

When i took the piston out the top ring was worn to fuck so it had no purpose and to bottom one was broken and a bit of it was missing, also the skirt of the piston was shattered and there was a huge chunk missing, obviously the fragments from it caused all th dents, but i need to know what caused this problem as i am buying a new kit and really cannot afford for this to happen again.

I was told that my jetting may have been abit lean(i didn't do it) and caused the engine to overheat, however the problem i have it that there is no number on my jet so i do not have a clue to what size it is, also i have a manual choke which i left up on the first start of the day and get a syringe, take a drop of petrol out of the tank and inject the pure petrol into a pipe that it right where thee intake it past the carb and everything so that it starts first time everytime, could this bee sum sort of pre-ignition thing that could cause a seizure? Also i was told that changing the air filter could have fucked it up, but its not that much of a difference it as both were of similar size? Or could there bee another factor?

Any insight would be much appreciated, thanks!

the air filter maybe the same size but it will have different filtration properties ( let more air through). this will lean the engine out causing pinking.

if that much damaged was caused to the top end i would strip down the entire engine and make sure no nasty bits of metal are hiding in the cases!! check you crank bearings and all your seals.

when rebuilding it look on the forums on here i guarantee you will find info on jetting a 70 speedshite somewhere. as that unknown jet would no doubt have lead to the failure in my opinion. and sort out the choke on the bike the idea of injecting fuel with a syringe doesnt sound right to me

it ran lean.. ie too much air, overheated and heated the ring to the point of snapping... secondly, introducing fuel to your engine in liquid form with no oil is basicly washing your engine... washing it CLEAN of all the oil it has in the fuel to protect it.. this wont help. sort the choke... off the top of my head a speedy is a 72.5 (stripped 1 in my life about 6 years ago) but dont quote me.. ether way if somethings broken, dont bodge at it to make it work some more, fix the problem.. the air box's on these are ment to be water tight and air restrictive.. its a good thing, keeps fuel usage down and rain out of your engine.. even a slightly less dense filter element in the box will require a bigger jet to compensate.. just how much is down to someone with experience to work out/for you to read up a little more on..


replace ALL broken parts, refer to the manual/peugot uk (they will have jet info) and look in the guides section for carb setup bits and bobs