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@benfromreu avatar
UTC

Enthusiast
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
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Posts: 51
Location: Ottawa, Canada
 
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@benfromreu avatar
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
Joined: UTC
Posts: 51
Location: Ottawa, Canada
UTC quote
Riding my 2008 S150 home today I started hearing a back fire sound and it sounded like a popping sound. I pulled over and gave it some revs while leaning down. It is definitely sounding a little rough.

Kept going and the sound started getting worse. I pulled over again and called the wife to bring some oil. I had noticed that it was leaking a bit of oil through probably because I used the same gasket as last time (should have replaced it I guess).

Kept going and the sound just got worse. It is popping and back fireing like crazy when you give it some throttle. When you let off it runs fine and when it is idleing it runs fine too.

Anyone have any ideas? What did I do wrong? What should I check?
@kcphoto2008 avatar
UTC

Hooked
2009 Piaggio BV250
Joined: UTC
Posts: 357
Location: Crestwood, KY
 
Hooked
@kcphoto2008 avatar
2009 Piaggio BV250
Joined: UTC
Posts: 357
Location: Crestwood, KY
UTC quote
Two times I have heard a backfire or pop. Both happened when decelerating or at idle down times. One time it was a loose spark plug wire that was the cause but this also caused it to idle rough and it would also quit without warning when idling or decelerating. The other time is was gas in the evap. Same case there, the idle was erratic too.

Just my personal experiences from last spring and summer. Definitely get it looked at, it will probably get worse whatever the cause.
UTC

Ossessionato
scooterless
Joined: UTC
Posts: 2085
Location: Googleville
 
Ossessionato
scooterless
Joined: UTC
Posts: 2085
Location: Googleville
UTC quote
Re: '08 S150: Back fireing or Popping Sound - What is it?
benfromreu wrote:
Anyone have any ideas?...What should I check?
If it's not the plug wire, next would check for exhaust loose at the head.
OP
@benfromreu avatar
UTC

Enthusiast
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
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Posts: 51
Location: Ottawa, Canada
 
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@benfromreu avatar
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
Joined: UTC
Posts: 51
Location: Ottawa, Canada
UTC quote
Thanks!
Thanks, it seems to idle ok so I am hesitant to think it is an idle adjustment problem although it does die on deceleration when coming to a complete stop so maybe it is an issue. But it has had that issue for a couple years and this sound just started yesterday.

I've had gas in the line before and it was a different sound altogether and it wouldn't start.

I am leaning towards the spark plug line and the exhaust connection along with some idle adjustment. I'll check tonight after work. Thanks for your help!
OP
@benfromreu avatar
UTC

Enthusiast
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
Joined: UTC
Posts: 51
Location: Ottawa, Canada
 
Enthusiast
@benfromreu avatar
2008 Vespa S150, 2009 Vespa GTS300 Super, 2012 Triumph Bonneville
Joined: UTC
Posts: 51
Location: Ottawa, Canada
UTC quote
So I went to check the gasket on the exhaust and it turns out the nuts are totally loose. I wonder how that happened all of a sudden. Its a good thing I didn't lose them.

So I tightened them and it seems to be running fine.

Now I am just hoping that I didn't do any damage to the engine by sucking air into the engine from the exhaust. I'm not sure what could happen but it sure doesn't sound like a good idea.
@judy avatar
UTC

World Traveler
2007 LX150 Daring Plum Leonardo Da Vespa
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Posts: 29304
 
World Traveler
@judy avatar
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
UTC quote
BEN i'd check things more regularly if your roads are as bad as ours our these days. I had my side stand bolt fall off. Wha? emoticon When i get my new rear brake line put in i'm going to be checking all the bolts because i' getting hammered with all the bumps etc in the roads these days. I wouldn't worry as i don't think you did any damage, you noticed it right away.
@jameze avatar
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Member
LX150 - Black w/Sport Seat
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Posts: 30
Location: Los Angeles, CA
 
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@jameze avatar
LX150 - Black w/Sport Seat
Joined: UTC
Posts: 30
Location: Los Angeles, CA
UTC quote
Had the same problem on my LX150. Turned out it was a loose exhaust. They are hard to get at but check the bolts holding the exhaust to the engine. You can get to them by removing the cover below the front of your seat.
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