OP
UTC

Member
Vespa GT 125 L
Joined: UTC
Posts: 7
Location: United Kingdom, Essex
 
Member
Vespa GT 125 L
Joined: UTC
Posts: 7
Location: United Kingdom, Essex
UTC quote
Hi all I have been having issues of my bike not going over 55 turned out to be a cdi I have replaced that but now there's another problem. on the first run it ran great got over 60 but ran out of space I then parked up to celebrate went back out 5 mins later pin the throttle it accelerated for about 20-30 seconds and started to engine break I then blipped the throttle couple times and kept it at 1/4 throttle seemed to run fine

Figured out that if I blip the throttle and keep it at 1/4 for a min I can then pin it for about 20-30 seconds before again it starts to bog down

Don't wanna take it to the mechanic yet as I already know their gonna charge a fortune to diagnose and fix it hoping it's something simple as a carb clean spark plug or fuel filter
Any help please
Have a photo :)
Have a photo :)
UTC

Addicted
PK50XL, PK100S, ET3
Joined: UTC
Posts: 603
Location: UK
 
Addicted
PK50XL, PK100S, ET3
Joined: UTC
Posts: 603
Location: UK
UTC quote
Is this on the stand with the backwheel off the ground? If so, its probably some sort of rev limiter.
OP
UTC

Member
Vespa GT 125 L
Joined: UTC
Posts: 7
Location: United Kingdom, Essex
 
Member
Vespa GT 125 L
Joined: UTC
Posts: 7
Location: United Kingdom, Essex
UTC quote
Off the stand riding at 30-60mph and no rev limiter due to cdi change
@petercc avatar
UTC

Molto Verboso
Piaggio Beverly 300 ie - 2012
Joined: UTC
Posts: 1217
Location: Belgium
 
Molto Verboso
@petercc avatar
Piaggio Beverly 300 ie - 2012
Joined: UTC
Posts: 1217
Location: Belgium
UTC quote
That1GTL wrote:
(...)
Figured out that if I blip the throttle and keep it at 1/4 for a min I can then pin it for about 20-30 seconds before again it starts to bog down
(...)
It can be helpful if you share a bit more details of your Vespa.
From what year, what mileage, do you have service history, that kind of information.

If you can run it for 20-30 seconds full throttle before it starts bogging, then most probably it is not a rev limiter. A rev limiter comes in right away when the engine meets that max rev limit.

So it could well be that at full throttle there is not enough fuel flowing to the carb. The fuel level in the float chamber in the carb starts to drop and at a point the fuel-air mixture is too poor and the engine starts to bog.

The most easy explanations are the fuel tank cap venting is blocked or the fuel filter is clogged.

You can test these first: drive the scooter with the cap off or partly unscrewed (make sure not to loose it). If that does not make a difference then replace the fuel filter. It is cheap and not difficult to replace.
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