OP
UTC

Lurker
2003 Vespa ET2
Joined: UTC
Posts: 1
Location: NC
 
Lurker
2003 Vespa ET2
Joined: UTC
Posts: 1
Location: NC
UTC quote
Looking for help on this issues that has me stumped. It starts right up and runs smooth when warming up. When you head down the road it runs rough like the choke is on. I have checked and made sure the choke isnt stuck and is working fine. So I found if you touch the brake and the brake light comes on it takes right off and runs like a champ. Let off brake and runs rough. I thought it maybe a bad ground so ran a wire from the body ground right to the engine. Still the same issue. Anyone run into this or have any ideas. Thanks
@melt avatar
UTC

Enthusiast
Vespa 2013 LX125, 2017 GTS300
Joined: UTC
Posts: 80
Location: London
 
Enthusiast
@melt avatar
Vespa 2013 LX125, 2017 GTS300
Joined: UTC
Posts: 80
Location: London
UTC quote
Wild guess here, the regulator may not be doing it's job and the voltage is too high and the brake light kills enough volts for the ignition coil to run properly again at the correct voltage.To test this I guess putting the headlight on should have the same result.
@abner_bjorn avatar
UTC

Molto Verboso
2007 GT200, 2008 Yamaha C3, 2009 BV250
Joined: UTC
Posts: 1081
Location: Denver
 
Molto Verboso
@abner_bjorn avatar
2007 GT200, 2008 Yamaha C3, 2009 BV250
Joined: UTC
Posts: 1081
Location: Denver
@jess avatar
UTC

Petty Tyrant
0:7 And counting
Joined: UTC
Posts: 36806
Location: Bay Area, California
 
Petty Tyrant
@jess avatar
0:7 And counting
Joined: UTC
Posts: 36806
Location: Bay Area, California
UTC quote
I wrote that wiki article, and it was the first thing I thought of when I saw the post title. That said, I don't think this is the OP's problem. I think the issue here is electrical, though I am not sure exactly how. The wild-ass guess by melt is actually pretty good, I'd check that out first.

Some vintage Vespas turn OFF the brake light by grounding to the body when the rear brake foot pedal isn't depressed -- not sure if the ET2 uses the same trick or not (probably not) but thought it was worth mentioning.
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