Sun Aug 22, 2021 12:30 pm

Hooked
61 VBB and 79 P200
Joined: 01 Jan 2018
Posts: 229
Location: Folsom CA
 
Hooked
61 VBB and 79 P200
Joined: 01 Jan 2018
Posts: 229
Location: Folsom CA
Sun Aug 22, 2021 12:30 pm linkquote
I've never seen this happen before...one of my scooters suddenly started running like crap and when I opened the carb box I discovered one of the bolts had worked its way loose and created a massive air leak. It's weird because I've easily put 100 miles on her since the last time I touched the carb and all of it was trouble free.

Anyway, besides retightening the two bolts does anyone have two cents on this? I did pull the cylinder head and confirmed no damage there.



Sun Aug 22, 2021 12:38 pm

Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
 
Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
Sun Aug 22, 2021 12:38 pm linkquote
Get all new hardware, I had some like that and even loctite wouldn't hold them
Sun Aug 22, 2021 12:52 pm

Hooked
61 VBB and 79 P200
Joined: 01 Jan 2018
Posts: 229
Location: Folsom CA
 
Hooked
61 VBB and 79 P200
Joined: 01 Jan 2018
Posts: 229
Location: Folsom CA
Sun Aug 22, 2021 12:52 pm linkquote
sdjohn wrote:
Get all new hardware, I had some like that and even loctite wouldn't hold them
Including the studs?
Sun Aug 22, 2021 1:22 pm

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6105
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6105
Location: So Cal
Sun Aug 22, 2021 1:22 pm linkquote
There should be a spring washer on each bolt to keep it under tension when tightened down.
Sun Aug 22, 2021 1:27 pm

Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
 
Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
Sun Aug 22, 2021 1:27 pm linkquote
I'd do studs too, you don't know what part is jacked. And yeah SoCal is right make sue you have the spring washer in there too
Sun Aug 22, 2021 2:57 pm

Hooked
P200e
Joined: 13 Feb 2017
Posts: 125
Location: Eureka, Ca
 
Hooked
P200e
Joined: 13 Feb 2017
Posts: 125
Location: Eureka, Ca
Sun Aug 22, 2021 2:57 pm linkquote
Just put it on with the correct washer, tighten it down, and ride.

It's nothing.
Sun Aug 22, 2021 3:00 pm

Hooked
1959 Allstate w PX Engine
Joined: 29 Nov 2020
Posts: 257
Location: Los Angeles
 
Hooked
1959 Allstate w PX Engine
Joined: 29 Nov 2020
Posts: 257
Location: Los Angeles
Sun Aug 22, 2021 3:00 pm linkquote
Popgunandy wrote:
I've never seen this happen before...one of my scooters suddenly started running like crap and when I opened the carb box I discovered one of the bolts had worked its way loose and created a massive air leak. It's weird because I've easily put 100 miles on her since the last time I touched the carb and all of it was trouble free.

Anyway, besides retightening the two bolts does anyone have two cents on this? I did pull the cylinder head and confirmed no damage there.
There should be a spring washer under that bolt.

It looks offhand like you torqued the right side bolt, then tightened down that left bolt. What happens with Spaco carbs especially is they will get deflected by that steel bolt. When you go to torque down the left bolt you're fighting that deflection, so it feels like it's tightened down when it isn't. Both bolts have to be torqued in unison, slowly.

I'm betting you're fine if you torque 'em correctly, with maybe a new silicone gasket.
Sun Aug 22, 2021 3:04 pm

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3775
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3775
Location: Nashville
Sun Aug 22, 2021 3:04 pm linkquote
For the carb, I tighten then hand tight, then alternate 1/4 turns with the torque wrench until they both click. Ideally, they will click on the same turn.
Sun Aug 22, 2021 3:58 pm

Addicted
63 Lambretta LI 125 series 3, 71 Sprint Veloce , 2005 Vespa PX150, 1979 P200E
Joined: 04 Jul 2011
Posts: 972
Location: Tucson, AZ
 
Addicted
63 Lambretta LI 125 series 3, 71 Sprint Veloce , 2005 Vespa PX150, 1979 P200E
Joined: 04 Jul 2011
Posts: 972
Location: Tucson, AZ
Sun Aug 22, 2021 3:58 pm linkquote
I had a similar problem on my engine. At one point during the engine swap we put the wrong size engine case studs, not only made it run horrible but it also ran very hot and it would take 20-25 kicks just to start.

Another think that I found is that one of the carburetor 11mm hollow nut was cracked and therefore it wasn't tightening on the stud.

Your solution is to put brane new engine cases studs and brand new carburetor 11mm hollow nuts/bolts with the two sets of new washer each.
Mon Aug 23, 2021 7:06 am

Hooked
various, but less than I used to have
Joined: 20 Aug 2012
Posts: 108
Location: San Anselmo
 
Hooked
various, but less than I used to have
Joined: 20 Aug 2012
Posts: 108
Location: San Anselmo
Mon Aug 23, 2021 7:06 am linkquote
If the other bolt stayed tight, high probability your carb is warped now. Take it off and set it on a true flat metal surface.
Mon Aug 23, 2021 8:36 am

Hooked
'61 Cushman GS150, '62 GS160, '74 Rally 200
Joined: 20 Sep 2017
Posts: 109
Location: Seattle, WA
 
Hooked
'61 Cushman GS150, '62 GS160, '74 Rally 200
Joined: 20 Sep 2017
Posts: 109
Location: Seattle, WA
Mon Aug 23, 2021 8:36 am linkquote
I would only tighten anything related to the carb by hand, and never over tighten. Just tighten the screws until they are snug (and alternate, as suggested). I would not use a torque wrench. These scooters were designed for people to maintain (mostly) on their own, and do roadside repairs. It's really not that scientific.

Regarding your post question, you need to periodically go around your whole scooter and check all the bolts and screws, and tighten as needed (carb, wheels, steering column, etc.). Over time, these will all loosen to a degree.
Mon Aug 23, 2021 8:49 am

Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
 
Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 5139
Location: San Diego, CA
Mon Aug 23, 2021 8:49 am linkquote
for the carb bolts I recommend a torque wrench, it is EASY to overdo them
Mon Aug 23, 2021 5:19 pm

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3775
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3775
Location: Nashville
Mon Aug 23, 2021 5:19 pm linkquote
sdjohn wrote:
for the carb bolts I recommend a torque wrench, it is EASY to overdo them
I 100% agree with this.

The whole point of torque wrenches and torque specs is to ensure the right amount (neither too much nor too little) of tightening.
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