Modern Vespa

My Vespa LX 125 has been unused for a couple of months in the garage. Came to it today but it will not turn over either on the electric start or the manual kick start. Battery is fully charged and new - on the electric start I just get a "clud" noise like the starter motor is trying to kick in and lights dip but nothing else. The manual pedal start is just solid. No movement at all. Everything worked fine before putting in the garage and never had a problem before when i did this.. Any suggestions please on how to possibly free things up.

Doesn't sound good, mate. Could be a variety of causes, you will have to methodically eliminate one by one.

take of the variator cover, and have a look inside to see if something is jamming the front pully/sprocket (where the starter bendix is). Remove the bendix and make sure it works properly.

This is what I feared - However, strangely, after a few hours in the sun and another dozen twists of the electric start it suddenly freed up and is now turning over....weird.

I thought this problem had resolved itself but not quite. First thing it is stuck again but then frees itself after a few presses of the started. Does start but runs very rough and fuel is gushing out of the air filter. The mystery deepens - clearly not happy being left alone in the garage for a couple of months but not sure what to look at now....Help please..

It's a carbureted scooter. The "stuck" plus the "fuel gushing out of the air filter" sounds like a problem with the fuel float or float needle. Fuel is not being regulated to the appropriate level and it's brimming into the intake tract.

The "stuck" is likely the engine hydro-locking from the fuel running down the intake. Fix this so you don't end up bending a conrod or damaging other internal parts. You may want to check the oil to see if is smells like petrol; it probably will need a change.

Thanks for the advice. I will take the carb off and check everything.

Things are getting worse. Took the dipstick out to check oil and petrol came flooding out. Really weird - everything worked fine before I garaged the bike a couple of months ago. Sounds like something serious - any suggestions before I take the engine to a garage please?

Sounds like two faults have happened in series: petcock stuck open AND carb float needle stuck open. A full tank would just empty into the intake, and fuel would dribble down past the valves and past the rings into the sump.

This is an easy fix. No need to take to garage.
1) drain your fuel tank
2) replace your petcock with a new one, make sure the vacuum line valve on the new petcock is working
3) drain engine oil (you will not be able to get all fluid out)
4) new oil in engine
5) remove carb and clean the insides very well
6) install carb, start engine and drive around for 5km or so.
7) drain engine oil, and refill with new oil
8) drive around for 50km, then drain oil and refill
point is that you need to get all the petrol out of the engine. Other option is to remove the oil pan completely.

If you've driven for 50km or so, then it'll have easily have evaporated any petrol left after your 5km ride and refill.

Thank you. All makes sense and would explain why engine was "solid" for a while. I did replace the petcock and fuel filter last summer so should be OK but I will strip down and see. Thanks again...

Did you put the correct petcock last year when you replaced it? Point is that there are two kinds of petcocks - one for the models with a fuel pump, the other for models with no fuel pump. The fuel pump models have no vacuum controlled on/off valve. The non-fuel pump models have two lines coming out of it - the fuel line and the vacuum line. The vacuum line goes from the petcock to the intake manifold.

https://scooterpartsco.com/lx-150-air-and-fuel-c-3637_3646_3866/fuel-valve-petcock-fuel-tap-for-vespa-piaggio-p-4829.html

https://scooterpartsco.com/lx-150-air-and-fuel-c-3637_3646_3866/fuel-valve-for-vespa-lx-150-lxv-150-and-s150-674592-p-36427.html

Thanks again. Unfortunately I cannot access the links you sent. This is what I fitted. https://www.racing-planet.co.uk/aprilia-kymco-piaggio-vespa-malaguti-p-22063-1.html

Should have been OK but I will check.

The petcock you fitted has a vacuum valve on it, so make sure that you attached the vacuum line to it and to the intake manifold. You should also manually check to make sure the vacuum valve is working by disconnecting the fuel line and putting it into a bucket (no fuel should be flowing), then with the vacuum line disconnected from the intake manifold, use your mouth to suck on the line. Fuel should then start flowing into the bucket. Stop sucking, fuel should stop flowing. There is an inline filter in the vacuum line, sometimes that needs to be replaced.

OK - thanks for confirming. I will check it out tomorrow and report back.