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 Post subject: Re: 750 Weber woes - same same but different?
PostPosted: Mon Apr 17, 2017 3:28 pm 
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Joined: Sun Jul 30, 2006 12:00 am
Posts: 208
Location: Chicago-NW Suburb
model: 750 Paso
year: 1988
Check for voltage drop throughout the igniton circuit. I had stumbling, misses, fouling of plugs due to fouled contacts in the off/run/off switch. Biggest voltage loss was across it, and from there it feeds the coils. Coils were not getting sufficient voltage. I first tested before bringing out the vom, by cranking while in off position, and while spinning over, I flipped switch to run. It would start much better when I did that, so I opened the switch to find it grungy, and a clean up of it solved the fouling of forward cylinder plug and the stumbling and misses.


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 Post subject: Re: 750 Weber woes - same same but different?
PostPosted: Mon Apr 24, 2017 4:51 am 
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Joined: Wed Mar 02, 2016 2:52 am
Posts: 6
Location: USA
model: 750 Paso
year: 1986
Gotcha, there is quite a drop at the coil - 7.5 at both, so that must be something upstream. Will have a look at the switch.

I can confirm that it's running on the front cylinder only. The weird bit is that I get spark at both. Tried a new plug and get some intermittent back fires and an occasional stumble when I pull the known-running plug cap and try to run on just the rear. With the front plug cap pulled, wouldn't I have enough juice to run just the rear? Should probably avoid too much logic. Will do some more poking tomorrow.


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 Post subject: Re: 750 Weber woes - same same but different?
PostPosted: Mon Apr 24, 2017 7:35 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4981
Location: southern Germany
model: 750 Paso
year: 1987
It's a wonder that it runs at all with 7.5V. Also have a look at the wiring upgrade. You`ll find the info in the downloads thread on top of the P750 forum.


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 Post subject: Re: 750 Weber woes - same same but different?
PostPosted: Mon Apr 24, 2017 10:43 am 
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Joined: Wed Jul 21, 2004 12:00 am
Posts: 64
Location: Windsor, CT USA
Try cleaning the idle jets first, and run the bike for a while after the cleaning. The idle jets, being so small, tend to gum up when the bike has been sitting for a while. If that doesn't seem to help then adjust the idle mixture on both cylinders. I know that my bike can be sensitive to idle adjustment, with similar symptoms to what you describe, if the idle mixture screw is off by even 1/2 turn on one cylinder.

For reference, the idle jets are held by the screw-in carriers circled in yellow in the attached photo and the idle mixture adjustment screws are the ones circled in blue (sorry for the crappy picture quality!).

While you have the idle jets out of the carb, spray some carb cleaner through the open passages in the carb.

Also make sure that the air bypass screws are closed (circled in red), if one is open too far it may also have an effect on idle operation.


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 Post subject: Re: 750 Weber woes - same same but different?
PostPosted: Mon Apr 24, 2017 8:24 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1488
Location: Newzealand
model: 906 Paso
year: 1990
One bypass screw should be part open ..... best not to dick about with them if you don't have a set of vacuum gauges ............... and 7.5 volts is way low , get that sorted 1st , mine was showing 9v and it played up

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