Modern Vespa

Hi all,

I bought my daughter an ET4 50cc for her 16th birthday. Low mileage and stored in a shed for a few years (after the owner fell off).

Fitted a new battery, new spark plug, cleaned out the carburettor and got it started easily enough but have a severe problem with lack of power.

The scooter starts fine and will pull away sharply. Once it gets up to about 15mph it kind of stutters and does not pull at all well.

On a flat road it will gradually accelerate up to 30-33mph but as soon as it encounters a slight rise it slows to 20-22mph. Going up hill it will only manage about 15-17mph.

I expected it to be slow but it is more than that, I can feel somethiong is wrong but not sure what.

I have a spark and it runs so I'm assuming the coil is ok.

I've checked the vacuum pipe, sucked on the small pipe and petrol came out of the other one.

Carburettor float bowl has clean fuel in it.

The plastic cover on top of the carburettor (over the rubber diaphragm) was cracked so I replaced the whole carburettor with one I know was good (made no difference).

Took it to a local scooter specialist who had it for a while and then said 'There is something major wrong with the engine!. It did not generate enough power to even get his rolling road turning! He didn't want to take on the job of fixing it as he 'specialises' in two strokes. In fact he suggested I 'convert it to a two stroke' as they are 'much better!'.

I'm stuck now!

Apart from trying to source another engine.

Does any of this ring any bells with anyone?

Any help will be most gratefully received.


Thanks


Anthony

It is a two-stroke isn't it?

Forgive my patchy/nonexistent scooter knowledge but I assumed the ET2 was a 2-stroke 50, and the ET4 was a 4-stroke 125...

they released a 4 stroke 50cc model ... this is probably the problem ... 50cc are slow anyway but when you throw in 4 stroke ... well they're just slow

have you tried to derestrict it?

No, it's definitely a four stroke, Hi-per4 engine apparently.

jasterixstrange

Not tried to de-restrict it and expected it to be slow. But it definitely has a problem rather than just being gutless.

My other daughter has a two stroke et2 and its a fantastic little bike. Will get up to 40mph with it's expansion chamber! Too noisy though!

Check to see if it has a 78 main jet or a 75 fitted... UK dealers got a memo about upjetting them due to a total lack of power, and this i suspect is the problem, they tend to be quicker on partial throttle than full throttle.

Its never gonna be quick like the other ET2 you have in the family, but derestricted and running a 78main it should do 40mph without a head wind.

Ok, today I have ....................................

Replaced the engine/gearbox/exhaust with one I know is ok (took me ages and my back is killing me!).

Fired it up, drove off down the road fine, get to about 15mph and the bike nearly stalls! Nothing has changed it's still not working right! If you close off the throttle and then open it again the bike comes back to life a little and limps along.

So can't be the engine!

Now I'm really miffed!

Replaced the Coil/CDI and the Regulator Recifier with ones that I know are good.

Fired it up, drove off down the road fine, get to about 15mph and the bike nearly stalls! Nothing has changed it's still not working right!

So can't be the coil or the regulator/rectifier.

Tested the fuel tap by sucking on the vacuum pipe and fuel comes out fine. It's clean fuel to as I collected it in a jar and checked.

Looking at the Piaggio Fault Finding manual that I found on the net it sounds like the choke may be staying on (but remember I have tried 3 carbs now so if it is it must be a wiring fault).

Checked the feed from the loom with a multimeter. 0 volts when the ignition is off, 0 volts when the ignition is on but the engine is off, approx 15v when the engine is running. All of which looks like it's right.

So changed, ENGINE/GEARBOX UNIT, CARB/CHOKE (x3), COIL/CDI, REGULATOR RECTIFIER and EXHAUST, almost a new bike!

Only thing I haven't swapped out now is the wiring loom and the fuel tap!

This is obviously something really stupid but it's driving me nuts!

Help Please! javascript:emoticon('')

Answer questions asked.

Wayne B

I have an ET4 50 mines definatly a 4-Stroke goes pretty well aswell dunno if its de restricted but it will hit 45mph with ease. Sounds to me that your belt or clutch is slipping maybe some oil or something got in the transmission casing.

Whatever the original problem was, we are now looking for another problem (may be very similar) on a completely different loads of bits.

So, what size was/is that jet?

I know this may sound stupid and off topic, but once I had the same problem with my Rucks/Zommer and I changed my air filter and the Problem went away. 4 strokes should go 40ish at no problem. my 4 stroke 50cc Honda Ruckus/Zoomer goes 42MPH at no probewm.

are you using 93 octane fuel or higher, is your gear oil and motor oil at the correct amount?

The only thing I can think of that hasn't change is the wheels. So could it be wheel bearings? These would start to seize up with more heat generated by going faster...
Good luck & keep use informed as to how you get on.

cheekythomas

Main jet is standard 75, I think the 78 is for de-restricted bikes.

Wayne B

OK

jimc

I know what you mean about swapping the bits but this is the same problem. If you had ridden the bike as I have you would understand what I mean.

orange s150

Yes

Papa J

Interesting theory!



If I ever get it fixed I will let you all know what it was.

Thanks All

ATB,

I can see that the theories are all over the map, and that you are frustrated by the scoot. Why not take it to a service tech and get his/her diagnosis? If you want to keep the bike, it would be money well spent.

Even if you want to do the work for yourself, you could pay them to diagnose the problem and get you working on the right thing.

We're all shooting in the dark, there don't seem to be many 4-stroke ET2 owners on the board.

Len