Modern Vespa

hi there need some advice if anyone can help as its driving me crazy now ,i have a vespa lx 50cc 2 stroke ,i replaced the air inlet manifold and now when i open the throttle full the enginge cuts out on me ??it idles great but full throttle engine dies and have to drop the throttle down,i checked for air leaks even replaced the manifold with another new one ,ive even put the old one back on,still the same ,tried the mixture screw no joy,new piston and rings ,new spark plug,new ht lead,stripped carb down and cleaned ,

sorry if this has been covered before im a newbie to scooters and really need help on this ,could it be a fuel starve ? or wireing ?if anyone can guide me in the right direction id be very grateful =(

ok update : took carb of today and fitted a new jet ,bike starts up nice take it for a ride get 40mph out of it ,suddenly all power and lights etc turns off have to pull over bike wont start wait 5 mins bike powers back on can drive away ,i go 25mph to get it home ,take out again later same thing runs nice get to about 35mph lost all power again in engine and electrics? wtf is goin on lol

You say lost all power. Will it turn over but not fire, Some lights no starter/be totally dead (no lights)? Give me some info.

Fuel starvation look for kinks along the fuel line/tap, sediment in the bottom of the tank.

What's the condition of the reed petals. Might have fooled with them messing with the manifold.

As far as electrical maybe immobilizer, pulsar coil/stator, ignition circuit grounding out.

hi there, ive put new reeds in so there all good ,it was strange with power issue as i was going along and then suddenly the whole bike switched off, not just the engine but the lights on the speedo ,it was like i turned the key ignition of and the bike slowed down totally ,i then pulled over to the side of the road and tried to start bike up again but no joy for about 5 minutes then it powered up again using electic starter and i was able to ride it back at about 25mph ,once i was near home it happend again ,but this time couldnt start bike up for at least 20 mins ,

things ive replaced over the weekend are:new spark plug,new reed valve,new inlet manifold ,new piston and rings ,new jet on carb,and carb totally clean out,new ht lead,

its like the engine gets to hot or theres no fuel getting to it ,but then why would it idle ok and ride for abit before comming to a stop ?

no offense meant lazyboy, but "not so modern" is not really the place to get an answer on an lx 2t

ry the rest of Modern Vespa for people who know automatic vespas

hi sorry didnt know id put it in that section ,im new to the forum and just started a new topic ,if admin wants to delete the posts or move it to the right section its cool ,im just trying to find out what is happening as im new to scooters ,and i came across this site in a search for my answer

It was in the general section. Not sure why it was moved to the NSM.

You say lost all power. Will the starter turn over but not fire, Some lights no starter, Nothing at all?

Does the bike have an immobilizer and a red LED on the dash? See if it flashes a code sequence next time you break down.

As far as to why you're having electrical problems download the service manual from the wiki section and look at testing the keyswitch, immobilizer, pulsar coil/stator, loose HT coil lead.

There is neither an immobilizer, nor a kill switch on that model.

hi the starter will turn on but the engine will not work ,no immobilizer,gonna take the head of again and check piston is getting oil and hope it was,nt a mini sieze? i dont no just seem to be going round in circles lol

moved to general discussion where the modern vespa experts are

Not that many 2T experts here though, which was why it was moved to NSM.

Hey-ho, lets see if the few 2T gurus in GD can help...

hot potato!

So, just to take stock of the situation:

1) what carb are you running (17.5?)
2) what jets do you have in there now
3) what clip position do you have for your needle jet, and what needle is it?
4) your bike is 100% stock? No kits, pipes, etc?
5) your initial problem you posted about, which was it would die when you opened the throttle, is gone?
6) now it dies at high rpms or wide-open-throttle - we don't know which for sure precedes the death, yes?

Regarding #6 - you need to isolate if this is an electrical problem for sure. When it dies - as SOON as it dies - and won't restart - you should check for spark. Checking at any other time, when it might be working ok at that moment, won't help.