OP
UTC

Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
 
Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
UTC quote
Hi, I have a 2017 Vespa (50cc, 4 stroke, 4 valve) that's running poorly. It's historically been hard to start, and when it's started it's very weak - accelerates slowly and doesn't reach top speed.

I've cleaned the carburetor, replaced the air filter, replaced the spark plug. Serviced regularly with new oil/filter.

Recently I replaced the inlet manifold, since it was leaking. After replacing it, it now starts just fine. However, it stills runs poorly. The running has never been "rough", it runs smoothly, just very weakly.

I would appreciate any pointers...there are no good Vespa mechanics in town (I live in Stockholm, Sweden), and the one that there is didn't even find the leaky inlet manifold, only charged me a hefty amount after only adjusting the idle rpm (way too high) and calling it a day.

Kalle
UTC

Member
et4 125
Joined: UTC
Posts: 49
Location: Hampshire England
 
Member
et4 125
Joined: UTC
Posts: 49
Location: Hampshire England
UTC quote
do you have a manual for it ?
have the valve clearances been checked
or the resistance values for the coil
OP
UTC

Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
 
Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
UTC quote
sparkplugofdestiny wrote:
do you have a manual for it ?
have the valve clearances been checked
or the resistance values for the coil
Thanks - I do have a manual, yes. I haven't checked valve clearance or coil. I'll see if that's something I can pull off myself.

I'll just ask a dumb question in the meanwhile about valve clearance, what could have caused a problem there? Say over-revving (it's de-restricted)? This Vespa haven't got many miles on it, that's why I am asking.

Note also that since I live in Sweden it doesn't run for half of the year, which I know isn't great for any engine.
UTC

Member
et4 125
Joined: UTC
Posts: 49
Location: Hampshire England
 
Member
et4 125
Joined: UTC
Posts: 49
Location: Hampshire England
UTC quote
i had trouble with my et4 125

one of the things suggested to me was check the valve clearances
as this can effect compression

it may not be that but worth a check .
UTC

Hooked
2020 primavera 150
Joined: UTC
Posts: 423
Location: Lorton virginia
 
Hooked
2020 primavera 150
Joined: UTC
Posts: 423
Location: Lorton virginia
UTC quote
Did you try some sea foam cleaner to fuel tank ? I would check the fuel tank petcock ( on bottom of gas tank) I would just replace it with the hoses because of the year.
@baba12 avatar
UTC

Molto Verboso
2018 Vespa 300 GTS Touring
Joined: UTC
Posts: 1355
Location: NYC
 
Molto Verboso
@baba12 avatar
2018 Vespa 300 GTS Touring
Joined: UTC
Posts: 1355
Location: NYC
UTC quote
You have cleaned the carb and air filter and you have a new spark plug as well.
Either bad fuel (clean the fuel filter and use something like sea foam in the tank) or you have some air leak happening around the carb seals to cause to not have full compression.
Between what others have suggested you should have a solution. I don't know if the battery could be bad (but then I don't know if these have a battery or not)
UTC

Hooked
2020 primavera 150
Joined: UTC
Posts: 423
Location: Lorton virginia
 
Hooked
2020 primavera 150
Joined: UTC
Posts: 423
Location: Lorton virginia
UTC quote
The only fuel filter is on the fuel petcock.It is a small screen.
@spacedog avatar
UTC

Hooked
2005 GT200L: (-Jiffy5-) 2013 GTV300ie: (-RBBaron-) 2021 GTS 300 hpe
Joined: UTC
Posts: 138
Location: Canada
 
Hooked
@spacedog avatar
2005 GT200L: (-Jiffy5-) 2013 GTV300ie: (-RBBaron-) 2021 GTS 300 hpe
Joined: UTC
Posts: 138
Location: Canada
UTC quote
Glad you got the starting issue fixed. So you say it doesn't accelerate very well, and I wonder if you have changed the belt yet? It is 5 years old if you haven't. Lightly sanding the pulley surfaces while you are there too. Just a thought.
OP
UTC

Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
 
Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
UTC quote
Thanks everybody, I really appreciate it. I'll work my way through your suggestions. This has really been bugging me, and I was a bit bummed when the new inlet manifold didn't solve the running issue (since there in fact was a leak). I'll keep you posted, if you think of other causes keep 'em coming!
OP
UTC

Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
 
Member
Vespa Primavera 50cc 4T 4V
Joined: UTC
Posts: 5
Location: Sweden
UTC quote
spacedog wrote:
Glad you got the starting issue fixed. So you say it doesn't accelerate very well, and I wonder if you have changed the belt yet? It is 5 years old if you haven't. Lightly sanding the pulley surfaces while you are there too. Just a thought.
Thanks, I haven't changed it. But if the belt were slipping, wouldn't the revs stay up while the speed/acceleration stays down? On a typical acceleration or even on an uphill, the revs are staying consistent with the speed/acceleration (or lack thereof...).
@spacedog avatar
UTC

Hooked
2005 GT200L: (-Jiffy5-) 2013 GTV300ie: (-RBBaron-) 2021 GTS 300 hpe
Joined: UTC
Posts: 138
Location: Canada
 
Hooked
@spacedog avatar
2005 GT200L: (-Jiffy5-) 2013 GTV300ie: (-RBBaron-) 2021 GTS 300 hpe
Joined: UTC
Posts: 138
Location: Canada
UTC quote
Crazy Chester wrote:
Thanks, I haven't changed it. But if the belt were slipping, wouldn't the revs stay up while the speed/acceleration stays down? On a typical acceleration or even on an uphill, the revs are staying consistent with the speed/acceleration (or lack thereof...).
Yes, you are right. It doesn't sound like the belt is slipping then.
@jrt avatar
UTC

Member
et4
Joined: UTC
Posts: 32
Location: East Cheshire
 
Member
@jrt avatar
et4
Joined: UTC
Posts: 32
Location: East Cheshire
UTC quote
Similar problem has just happened to me. It was running great then all of a sudden it has lost about 15 kmh and feels like it is holding back when it hits 60kmh when it used to hit 75.
I have replaced the variator, messed about with different roller weights, changed vacuum/ fuel lines, checked inlet manifold-this does have a crack but only on the outside- so I have filled that with some epoxy while I wait for a replacement.
New plug, ht cap, cleaned the carb' out on Friday and checked the automatic choke was working well. I'm not happy with this as I don't think it's extending as much as it should and retracting as far as I think it should. I have also ordered a new belt as it is 17 months old and is showing signs of wear and has lost a few mm in width.
I will put the new choke and belt on this week and see if it helps before looking at the valves.
I will watch your thread and report back later.
I have had the transmission cover off more times last week than I care to remember 😂.
Et4 50 cc.2004.
@jrt avatar
UTC

Member
et4
Joined: UTC
Posts: 32
Location: East Cheshire
 
Member
@jrt avatar
et4
Joined: UTC
Posts: 32
Location: East Cheshire
UTC quote
I marked the variator to see where the belt got to and this is the result last week with new 6.5 g rollers, new Malossi variator and white clutch spring. Since then I am on 3.2 and 6.1 rollers and it is slightly better. I'll see how much further it has traveled whe I change the belt later on.[img][/img]
Forum member supplied image with no explanatory text
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: 0.0154s ][ Queries: 4 (0.0062s) ][ live ][ 313 ][ ThingOne ]