OK, but why two??
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Molto Verboso
150 Sprint Veloce,Vespa GTS 300
Joined: 22 Feb 2010
Posts: 1133
Location: St Neots Cambridgeshire England
Mon Sep 14, 2020 6:00 am quote
Ok, while getting off the ECU unit, to get hold of the code number stamped on the side, I always wondered why there's two throttle cables on the unit. I know the bottom one (furthest away) is controlled by the throttle on the headset, but what about the bottom one, that doesn't seem to do anything, except move in time to the other one!
Just curious!

Graham

Ossessionato
BV350, Primavera 150, Yamaha Zuma 125
Joined: 06 Jun 2013
Posts: 3173
Location: The Twin Cities of Minneapolis/Saint Paul, Minnesota
Mon Sep 14, 2020 6:05 am quote
They pull in opposite directions. One pulls to open the throttle, the other closes the throttle.
Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2012 Honda NC700 DCT
Joined: 02 Mar 2013
Posts: 6148
Location: Madison, Wisconsin
Mon Sep 14, 2020 6:12 am quote
Generally done so if the spring fails you can "push" the throttle closed.

If the spring breaks on a larger displacement engine, the throttle remains open. Perhaps widely open; enough so that taking your hand off the bar to turn the key off becomes hazardous. By having two throttle cables, the return side can force the throttle closed without the spring assist.
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2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3006
Location: East Anglia, a dryer region of the UK than Israel
Mon Sep 14, 2020 6:38 am quote
Yes, it's a safety measure to make sure you can always close the throttle with no issues.
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Yamaha Tricity 155 Urban 2019 - MV Agusta 125 RS 1956 - Yamaha Majesty 250 DX 1998
Joined: 21 Jul 2007
Posts: 4010
Location: Latina (Italy)
Mon Sep 14, 2020 9:08 am quote
Even on mine it's like that, it gives me the impression of having a twin-cylinder scooter.
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'15 Blue GTS300 Super, '18 White GTS300 Super
Joined: 01 Nov 2005
Posts: 2729
Location: Sydney, Australia
Mon Sep 14, 2020 3:04 pm quote
On my two=stroke Vespas there was just a return spring, and it wasn't strong enough to snap the throttle shut, but would keep it in position if I was riding no hands.

On one occasion when my throttle cable snapped, I pulled the slide out and rode home full throttle all the way. Cut the engine to stop at the lights, then start the engine, crash it into gear and take off like a bat out of hell. On another occasion I just screwed the idle screw all the way in and rode home on a very fast idle. Wouldn't dream of those antics with a 300, but they don't have a carb anyway.

With the old two-strokes, whatever happened you could do some sort of road-side repair to get yourself home. No clutch, no gear cable, no problem. And you had a spare wheel. With modern scooters you just have to phone for assistance.
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Yamaha Tricity 155 Urban 2019 - MV Agusta 125 RS 1956 - Yamaha Majesty 250 DX 1998
Joined: 21 Jul 2007
Posts: 4010
Location: Latina (Italy)
Mon Sep 14, 2020 8:58 pm quote
Mike Holland wrote:
... then start the engine, crash it into gear and take off like a bat out of hell.


Very nice scene, i almost seem to see you ...
Yes, modern scooters have lost their souls along the way; when i had the PX i was sure that i would always come home.
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