piaggio zip 50 will start but won't drive.

Hi all i am gary and I'm new to the forum. i have just baught myself a piaggio zip 50 2 stroke.
the problem i have is that it will start first time but it won't move. i have put in a new clutch, torque spring, drive belt and rollers. but still it won't move. When i rev it it seems to rev good for a second or two and then the rev dies for a second then revs back again. even with the throttle strait back. i am really stuck as i thaught i new quite a lot about bikes but new i know I've haven't got a clue lol. thanks for the time to help me guys.

 

Seems electrical to me... Tried changing the spark plug? Usually as simple as that

 

The sparks fine i have checked everything. it start first time every time. i took the head of it today to check the pistone and the ring seemd a bit loose as it was mooving easyly. so i have took the piston out and I'm going to buy a new cylinder kit for it maybee a 70cc kit. and hopefully it solves the problem.
i diid think that if the rings had waer in them then that would reduse the combustion resulting in not enuff push to push the belt fast enuff but not to sure so ill try new kit and see what happens.
ill update when I've done and let you know if it fixes it.

 

I believe if it was a ring problem (thus, less compression), the problem would be more noticeable at low rpms and it would be hard to start up... I'm quite new to these things tho, so don't take this as something that's 100% correct

 

Yeah i think ypur right mate. anyways gonna change the piston and rings as this one looks old and dirty.
i think it will ithere be the spark plug or maybee cdi problem so I'm gonna change everything and see what happens. cheers

 

I'd also check that the carb jests aren't blocked. It could conceivably be the crankcase seals, leaking compression away during the transfer part of the cycle, but check the simpler things first.

 

Yeah i was thinking about the crank bit of things but how would i go about fixing it. like what tools would i need exc. wwould i have to take the full engine apart to sort it out. like give it a strip down and rebuild? Cheers

 

Lol that's not mines i stole the pic of the internet lol. mines is just basic at the moment but I'm planning on doing similar the the pic but with a paint job the reflects the spitfire and I'm going to put the nrg fairings on it and put the shark mouth around the head lights. i have a good fue plans but really want to fix the running problem before is start. I've never done an engine rebuild so it should be fun to learn. I'm thinking of painting the engine casings a nice electric blue gloss couler to make is stand out but not sure yet. it will take a good while to complete but when i start ill post picture updates in the project section.