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PostPosted: Wed Sep 03, 2014 2:24 pm 
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Joined: Mon Aug 26, 2013 11:39 am
Posts: 17
Scooter Model(s): 1978 Piaggio Vespa P125X 150 Top End, S.I.P Road 2.0
P.S: I posted this on modern vespa. http://modernvespa.com/forum/topic132432

Hey Guys, my bike is bogging when i rev it up. I have checked the following:

1. New Points and Condenser installed a few weeks ago (bike ran fine after that).
2. Checked timing with timing light (21 degrees before TDC). (not an expert at setting timing)
3. Unclogged the exhaust using Drano.
4. Checked/cleaned all the jets.

It basically idles fine but as soon as you try to rev it, it bogs/hesitates. Even WOT. Doesn't want to run at all. What else can i check?

The last major change was new points and condenser. The other thing i added was mixture screw grommet on the airbox. I cant think of anything else i have changed.

With the air filter off there was a lot of fuel spitting out when WOT (didnt look atomized)??

The choke and slide seem to functioning correctly, by that i mean they go back in place when released etc.. Could it be the float assembly? needle? etc..? Should i just order a rebuild kit and do a full rebuild? It is definitely out of commission for now

Here is a 40 sec video showing the problem. Idles fine and then i roll the throttle and it sounds like a bass drum.

http://tinypic.com/player.php?v=2wrhyko ... Adq1fldUk0


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PostPosted: Wed Sep 03, 2014 9:57 pm 
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Joined: Sat Aug 05, 2006 9:45 pm
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Location: Poughkeepsie, NY
Scooter Model(s): 64 Allstate 125 75 Rally 200 84 PK125 Automatica 62 125 64 Cento 79 P200 3 smallframe 85 T5 69 Ape D
clean the carb, remove the jets and make sure they are clean and the holes unobstructed. I use a set of welding tip cleaners, but any stiff fine wire should do the trick - you're not opening up the metal, just cleaning, so don't get too aggressive. Sounds to me like you're not getting gas = idle jet is fine, running jet throttle, and mixer jets.

Since you said you'd do the gaskets, you can check and clean the jets while the carb is out and apart. It is really easy to do, plus, you'll stink like gasoline!

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PostPosted: Wed Sep 03, 2014 10:06 pm 
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2000cc Scooter Royalty
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Joined: Sat Aug 05, 2006 9:45 pm
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Location: Poughkeepsie, NY
Scooter Model(s): 64 Allstate 125 75 Rally 200 84 PK125 Automatica 62 125 64 Cento 79 P200 3 smallframe 85 T5 69 Ape D
I know checking for the air leaks is important, but it doesn't sound like one here - you're not racing, just not getting fuel when you add more air (opening throttle)

this looks good enough if you haven't done it before: https://www.youtube.com/watch?v=wZ7eaFzQPSs

the jets should be the 2 brass screws next to the intake opening once you take off the air cleaner - don't drop them inside the engine!! they need not be tightened in all torqued up and all, just snug.

Image

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"Ever pick your feet in Poughkeepsie?"

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PostPosted: Mon Sep 08, 2014 10:26 am 
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Joined: Mon Aug 26, 2013 11:39 am
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Scooter Model(s): 1978 Piaggio Vespa P125X 150 Top End, S.I.P Road 2.0
Thanks Mario, I did a complete Carb rebuild this weekend, new gaskets etc. (followed the video) and still same issue. Idles fine but when i open up the throttle doesnt do anything. Could it be my soldering job on the new points and condenser? It was my first time soldering anything. I read somewhere that if there is short in the stator it can cause these symptoms?


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PostPosted: Tue Sep 09, 2014 7:59 pm 
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2000cc Scooter Royalty
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Joined: Sat Aug 05, 2006 9:45 pm
Posts: 2779
Location: Poughkeepsie, NY
Scooter Model(s): 64 Allstate 125 75 Rally 200 84 PK125 Automatica 62 125 64 Cento 79 P200 3 smallframe 85 T5 69 Ape D
Ohh, first time soldering can be a great job or cold solder joints. How bad did the wires look on your stator? Was the insulation crumbling off?

There are several places which can re-wire the stator, and you could do the whole thing mail order too. You would first make a reference point
to keep where the stator is lined up so you don't have to guess later. (can be a small punch mark on both the stator and case, a scratch, or if you're adventurous - a photo, but if you combine
the photo and one of those marks you'll be safer.

The wires lead out of the flywheel area through the case to the junction box. Unscrew the top, take a pic, and some as you disconnect the wires as you prepare to gently pull the wires through
so you can remove the stator. (Installation is reverse, I tie a small string around the wires and pull the wires up through the case gently then re-connect)

Call Scooters Originali - they're close-by in PA and have done this work -

or Saints Cycle Works - I had a stator done there - put it back in and started my bike 1st kick.

Make sure your timing is correct, and check those jets out -

Image

to the right is the main jet and mixer (stacked together (actually one slides over the end almost like a lego connection

Image

(the article attached to above) - http://modernvespa.com/forum/topic47016

Best of Luck! Post your results!

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"Ever pick your feet in Poughkeepsie?"

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PostPosted: Thu Dec 18, 2014 5:44 pm 
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Joined: Mon Aug 26, 2013 11:39 am
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Scooter Model(s): 1978 Piaggio Vespa P125X 150 Top End, S.I.P Road 2.0
It ended up being a faulty condenser.


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