Lambretta 'breathing problem'

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Scootermonkey
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Tue Apr 05, 2016 10:52 pm

Any ideas on this one guys? Lambretta, 175 top end, 42mm clubman, 22mm carb. Starts first go from cold but quickly starts choking itself. Take the air hose off, runs sweet as a nut! Put the rubber back on and it dies. Clear airway through hose and air filter box/scoop. Even removed the filter element. Tried three Jetex carbs, one brand new and was running perfect on another scooter. Tried a brand new Scootopia carb, tried and tested on yet another scooter. Think I've tried every jet/slide combination, still no joy. Starting to annoy me now. Never had this problem before. Any help appreciated
How hard can it be!
Lambretta, the finest scooter............IN THE WORLD!

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Knowledge
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Main scooter: GP
Location: Ipswich
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Tue Apr 05, 2016 11:00 pm

Is the restrict or still in the air scoop under the seat? If in doubt, remove the air scoop but keep the air box, just in case it is the air scoop (though this is usually an issue when running at mid to high revs)
Martin

Muppet
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Tue Apr 05, 2016 11:11 pm

try changing the air box for a GP one
im not a complete idiot
.
.
s me of the piec s are mis i g

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Scootermonkey
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Wed Apr 06, 2016 7:25 am

Changed the airbox and scoop for a S3 one, not even using a filter element. Airways completely clear
How hard can it be!
Lambretta, the finest scooter............IN THE WORLD!

Chris in Margate
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Wed Apr 06, 2016 7:56 am

Suddenly happened, slowly got worse, or always been like it ?

bristolmod
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Main scooter: Lambretta TV175 S3- what else!
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Wed Apr 06, 2016 8:56 am

air hose weak and collapses under load? Try another air hose.

Chris
Scootering since 1968.

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EddieStone
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Wed Apr 06, 2016 9:02 am

Is the choke cable/mech working properly. I'm wondering if the choke is still open a little bit, if the cable is tight or something?

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Scootermonkey
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Wed Apr 06, 2016 5:19 pm

Engine just had a full rebuild. So first time running. Seems to want to cut out as soon as the rubber hose goes near the carb. But will start easy from cold. Runs 30 seconds and bogs down and wwants to die
How hard can it be!
Lambretta, the finest scooter............IN THE WORLD!

LeightonRB20
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Wed Apr 06, 2016 8:40 pm

As Bristolmod says; air hose collapsing. A problem with some Asian imported parts. Try another one that you know works.

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Scootermonkey
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Wed Apr 06, 2016 9:39 pm

The rubber is brand new, but I'll check it anyway. Cheers
How hard can it be!
Lambretta, the finest scooter............IN THE WORLD!

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