OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
Ciao Vespisti,

So, I have my S 125 and about 3 years ago I changed the electric harness due to an electric short. the oem brand new harness did not have a connection for an electric pump, so pump was removed, the carburettor manifold was changed. now fuel is pumped with vacum. my problem is that from cold is taking a little bit to start, about 4 seconds.

is this normal? I can live with a bit of delay, it has always been a bit lazy to start from cold, but now seems that she s getting lazier.

Btw, Battery is brand new, carb is clean, new plug and new air filter. bike has 34000 kms. I was thinking also valve setting maybe? Once it starts it goes lovely.

thank you in advance
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
I think the fuel cap is the culprit. If I start it without it it fires right up....anyone had this problem with the fuel cap?
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
UTC quote
retro s wrote:
I think the fuel cap is the culprit. If I start it without it it fires right up....anyone had this problem with the fuel cap?
That's not a fuel cap problem (it should be air-tight) but a tank venting problem. Check your tank vent.

In the UK, if the gas cap isn't air-tight, it's an MOT failure.
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
jimc wrote:
That's not a fuel cap problem (it should be air-tight) but a tank venting problem. Check your tank vent.

In the UK, if the gas cap isn't air-tight, it's an MOT failure.
Thanks. There was also an air bubble in the fuel line. Now its gone. Maybe it was the problem. One i started it without the fuel cap on, the air bubble disappeared
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
UTC quote
Double-check that fuel line for a tiny crack - if the fuel and vacuum lines are original it's time to change them out anyway.
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
jimc wrote:
Double-check that fuel line for a tiny crack - if the fuel and vacuum lines are original it's time to change them out anyway.
Thanks😁
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 15079
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 15079
Location: The state of insanity, SoCal
UTC quote
if the problem persists and you haven't checked the valve clearances, I would strongly suggest that you start with those.

very much describes your problem: difficult to start cold, starts fine hot.
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
greasy125 wrote:
if the problem persists and you haven't checked the valve clearances, I would strongly suggest that you start with those.

very much describes your problem: difficult to start cold, starts fine hot.
I believe you're right. I have never had the valves set, and with 34000kms i think its time.
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
greasy125 wrote:
if the problem persists and you haven't checked the valve clearances, I would strongly suggest that you start with those.

very much describes your problem: difficult to start cold, starts fine hot.
Btw, valves can be adjusted from that small opening below the seat right?
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44533
Location: Pleasant Hill, CA
UTC quote
retro s wrote:
Btw, valves can be adjusted from that small opening below the seat right?
Yes, but you have to swing the engine back 20 degrees or so. This means disconnecting the spark plug and undoing one end of the rear suspension at a minimum. It helps to put the centre stand on a bit of 2x4 to get the extra swing for easy valve cover access.
OP
@retro_s avatar
UTC

Hooked
vespa s 125
Joined: UTC
Posts: 462
Location: malta
 
Hooked
@retro_s avatar
vespa s 125
Joined: UTC
Posts: 462
Location: malta
UTC quote
Thank you
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 2005-2025 by Modern Vespa.
All Rights Reserved.


[ Time: 0.0124s ][ Queries: 3 (0.0016s) ][ live ][ 323 ][ ThingOne ]