OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
Hi all,
This is my first Vespa
First I know my way round a bike, but this 2002 et4 has me stumped, The last owner sold it to me as it cuts out.
Starts easy ticks over nice and pulls away smoothly but get to about 10mph or half throttle which ever comes sooner the engine dies, you can keep it running buy blipping the throttle but now will also be lumpy on tick over and cut out.
It will instantly start again and be fine until you reach that 10mph.

OK what have I tried, deep breath:

new plug
Disconnected the air box,
remote fuel line and tank with fresh fuel,
cleaned carb
checked valves,
checked compression,
earthed engine
changed exhaust (back pressure?)
checked loom
swapped coil and cap

Non of the above made a difference.

So I replaced:

stator plate which includes the pick up coil.

Made no difference.

At this point I bought another working ET4 and swapped:

carb
flywheel
CDI (getting round the key problem)
coil
plug with cap and lead
regulator recertifyer

All of the above made no difference.

So then run the first engine from the electrics of the new bike buy stretching the wires across so all the new bikes loom electronics is now used to run the old engine (the stator plate on the old engine is new) result, no difference.

I then swapped the stator plate just in case the new one is faulty, no difference.

Next strip the engine (bent not seating valve?) nothing its perfect in there.

OK guys, I bow to a greater knowladge, what have I missed,

Over to you

Many Many thanks James
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
Damaged jet? Do you get good flow?
Loosing compression somewhere maybe?
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
thank you the carburettor on it is off the bike and compression is good time to swap the engines over I think
@brown_beret7 avatar
UTC

Veni, Vidi, Posti
1975 Vespa GTR 125, 1976 Vespa V90 (Resto), 2001 Vespa ET4 125 (Sold), 2009 Vespa GTS300 Super
Joined: UTC
Posts: 6064
Location: Northants UK
 
Veni, Vidi, Posti
@brown_beret7 avatar
1975 Vespa GTR 125, 1976 Vespa V90 (Resto), 2001 Vespa ET4 125 (Sold), 2009 Vespa GTS300 Super
Joined: UTC
Posts: 6064
Location: Northants UK
UTC quote
Gee, what a gremlin you've got. My thought is Carb mainly but maybe the engine swap is simply the quickest fix to get you up and running.
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
changing the engine made no difference and reprogramming the key made no difference
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
Wow....stumper
@brown_beret7 avatar
UTC

Veni, Vidi, Posti
1975 Vespa GTR 125, 1976 Vespa V90 (Resto), 2001 Vespa ET4 125 (Sold), 2009 Vespa GTS300 Super
Joined: UTC
Posts: 6064
Location: Northants UK
 
Veni, Vidi, Posti
@brown_beret7 avatar
1975 Vespa GTR 125, 1976 Vespa V90 (Resto), 2001 Vespa ET4 125 (Sold), 2009 Vespa GTS300 Super
Joined: UTC
Posts: 6064
Location: Northants UK
UTC quote
chigs362 wrote:
changing the engine made no difference and reprogramming the key made no difference
Wow.Anything left on the bike not already eliminated?

Presume you operated the carb manually to rule out some oddity with the throttle cable?

You've done air filter...

You've tried remote fuel line...

Err..I'm coming up blank and certainly no better than you.

Keep this thread up the list and see what others pitch in - Fabio Dougie knows his ET stuff for one.
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
Was just thinking about this whilst at work, did you use the same fuel lines carb etc when changing engine and carb?!? One might be blocked?
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43731
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43731
Location: Pleasant Hill, CA
UTC quote
Timing out? A 'sticking' valve? Weak or damaged flywheel magnets? Had the last two (at the same time!) on my GT200 in Italy. It'd start, but run very poorly and cut out at idle.

Can't think of anything else not mentioned so far.
@broz avatar
UTC

Hooked
2001 ET4
Joined: UTC
Posts: 289
Location: Charlotte,NC
 
Hooked
@broz avatar
2001 ET4
Joined: UTC
Posts: 289
Location: Charlotte,NC
UTC quote
Wow! When you say you known your way around a bike you weren't joking. I pray I never run into this kind of problem because I will be screwed.

I hope with some help from jimc you get it figured out. Good luck.
Broz
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
yes carburettor has been replaced but i have an idea.........
@raputtak avatar
UTC

Ossessionato
2016 GTS 300 Super - red, of course.
Joined: UTC
Posts: 4755
Location: Hertford, North Carolina
 
Ossessionato
@raputtak avatar
2016 GTS 300 Super - red, of course.
Joined: UTC
Posts: 4755
Location: Hertford, North Carolina
UTC quote
The mirrors. It's gotta be the mirrors. The only thing you haven't swapped out.



Wait, did you unplug the battery tender before you set off?


Maybe you are having a panic attack once you reach that dizzying speed and are unaware that you are pressing the engine cut-out switch?


Maybe ... SHUT UP RAP, AND GET ON WITH YOUR LIFE.

Yes sir.
@judy avatar
UTC

World Traveler
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
 
World Traveler
@judy avatar
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
UTC quote
I'm going to get dinged because i don't know the name of what i'm going to say and i hope you understand me. On the carb there's this rubber condom looking thing and if that's not perfectly seated it will cause the exact symptoms that you describe. A few years ago we took the carb apart to clean it and it wasn't put back on exactly right. Scooter started up fine got to about 10mph and then died. No power We then put it back on perfect and the scooter ran beautifully.I wonder if a tiny hole in it would cause the same symptoms as well. I would recheck it. Couldn't hurt. Not a mechanic but just my thoughts.
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
vacuum diaphragm?
@judy avatar
UTC

World Traveler
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
 
World Traveler
@judy avatar
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
UTC quote
Thanks LAE. 8) Clown emoticon Yes if it's not seated Exactly it will present with the symptoms that the OP describes. Been there done that. Crying or Very sad emoticon Thumbs up for you.
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
Razz emoticon not sure what i prefer, carb condom or vacuum diaphragm....

Still, OP said he switched carbs but it didnt work. i suppose it technically IS possible it could not be seated on both.....but
@judy avatar
UTC

World Traveler
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
 
World Traveler
@judy avatar
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
UTC quote
True but the symptoms are exactly what he is experiencing. Possible to have it move a bit when seating it. Probably isn't but it doesn't hurt to double check, i guess.
@danceswithdingoes avatar
UTC

Member
Vespa ET4
Joined: UTC
Posts: 30
Location: Kyogle NSW Australia
 
Member
@danceswithdingoes avatar
Vespa ET4
Joined: UTC
Posts: 30
Location: Kyogle NSW Australia
UTC quote
Is it insured?
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
Hi thankyou all for your input as I sed I bought another good working et4 to swap parts over and the carb was swaped from my bike to the new one and it runs good on that bike and the new bikes carb put on my bike made no difrence.

I am now thinking radio interference as I know these machines can sensitive to to interference hence you have to use a resiterd plug and cap.

I thought I may have got around that as once started you can unplug the imobelizer and swapping all parts with the other machine made no difrence anyway.

So i will dream up a way of isolating the cdi from the outside world .

Any one have a lead lined box I can borrow??

And no it is not currently insured lol naughty danceswithdingoes.
@lae avatar
UTC

Hooked
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
 
Hooked
@lae avatar
Piaggio B125, Yamaha YZF R6, Vespa GT125, KTM Duke 125
Joined: UTC
Posts: 328
Location: London
UTC quote
Wow if that turns out to be the case I'd have never guessed it. Chuck a kick start on there to see if it'll chug into life if you can (I'm not familiar with the et4)
Has to be a way to fire up the engine to see if it'll run, then just strip til barebones and slowly add until you find the problem.
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
Ha it worked, the CDI was getting interference from the engine, I held up a thick metal plate between the cdi and the engine and it runs fine as soon as I drop the plate it cuts out.

I have never seen or heard of this before, but as the cdi is mounted in front of your left knee in the leg shields I just drilled a couple of holes in the 1/4 inch plate and mounted it between the cdi and the frame using longer bolts so shielding it from the engine.

It now runs perfect, and with the leg shields on you cant see the plate, job done.

Thank you all for input it was nice to have a sounding bored.

Happy scootering
@broz avatar
UTC

Hooked
2001 ET4
Joined: UTC
Posts: 289
Location: Charlotte,NC
 
Hooked
@broz avatar
2001 ET4
Joined: UTC
Posts: 289
Location: Charlotte,NC
UTC quote
Congrats!
Smart Mofo.
Broz
@rgconner avatar
UTC

Ossessionato
GTS250
Joined: UTC
Posts: 2959
 
Ossessionato
@rgconner avatar
GTS250
Joined: UTC
Posts: 2959
UTC quote
Sounds like you are missing the resistors in either the spark plug, or the wire.

Does it drive an AM radio crazy?
OP
UTC

Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
 
Member
ET4 125
Joined: UTC
Posts: 7
Location: Fleet, UK
UTC quote
@ rgconner, plugs, caps changed for new ones and all put on the other working scooter and other working scooter still good, also same parts taken from the good working scooter and put on the bad one and made no difrence, plug, cap, coil and lead where taken out of the equation.

But still it good now.
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43731
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43731
Location: Pleasant Hill, CA
UTC quote
Good sleuthing, well done.
DoubleGood Design banner

Modern Vespa is the premier site for modern Vespa and Piaggio scooters. Vespa GTS300, GTS250, GTV, GT200, LX150, LXS, ET4, ET2, MP3, Fuoco, Elettrica and more.

Buy Me A Coffee
 

Shop on Amazon with Modern Vespa

Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com


All Content Copyright 2005-2024 by Modern Vespa.
All Rights Reserved.


[ Time: 0.0216s ][ Queries: 3 (0.0112s) ][ live ][ 313 ][ ThingOne ]