Vespa Piaggio Grande 79 no spark

Hi, trying to test spark on this thing with no luck. Firstly, does it work to spin the motor with an impact to test spark? For example all ignition switches on spark plug out spin crank with impact while grounding spark plug

Re: Vespa Piaggio Grande 79 no spark

You should see spark , if the ignition system is copacetic .

Re: Vespa Piaggio Grande 79 no spark

Thanks. Wanted to make sure before I went off the deep end on other stuff. I’ve been reading the web trying to find what it could be. This is the version with blinkers, I have the key in the most cw position and the other switch on also. I verifed the plug is ok by connecting it to the mower and giving a pull, to see it spark. I was trying to determine on the schematic how to bypass a bunch of stuff with a jumper wire just to see if I could get it, but having some trouble interpreting it

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Re: Vespa Piaggio Grande 79 no spark

Another test I just did was to spin the motor very fast with impact and I can see the headlight and taillight illuminate

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Re: Vespa Piaggio Grande 79 no spark

See the grey wire coming out of the magneto to the wire bloke/terminal .

Then 2 greys come out of the terminal . Disconnect the one going to the ignition switch . That should leave only the feed from mag to the ignition coil .

You could also test the ignition coil .

Coil test .

Re: Vespa Piaggio Grande 79 no spark

man its very dangerous to use an impact to start a motor, especially a vespa cuz what happens is you'll shear the crank threads by over tightening it then your done...

use a regular drill, take a look at myrons page under vespa electrical to gain an understanding of vespa spark issues, just ground the blue wire off the magneto, of course clean and set points.

Re: Vespa Piaggio Grande 79 no spark

Thanks for the tips. I should clarify not trying to start it with a 20v impact driver, just to spin it with the plug out of the head to see spark. I was able to see a small spark at the plug now when spinning it very fast, so I think all of the switches must be ok. It has ngk b7hs plug also which isn’t correct, so I have ordered a new plug and will look at the spark again with new plug. This ped was in a shed for 25 yrs sitting, I think it ran when parked.

Re: Vespa Piaggio Grande 79 no spark

b7hs is fine, clean and set your points.

Re: Vespa Piaggio Grande 79 no spark

Very faint spark was visible I should add, as compared to mowers or snowmobiles with same test, will work on the points. That Myrons site was something I had not come across, great info there. Much more readable schematics available there.

Thanks

Re: Vespa Piaggio Grande 79 no spark

Still don't use an impact to spin the crank, plug installed or not. Don't you have a normal handheld drill?

Re: Vespa Piaggio Grande 79 no spark

Clean all electrical connections . They should be clean , no corrosion , and scratch tight . That includes all grounds . Plug cap to HTwire . HT wire to coil . Clip a 1/4" off each end of the HT wire for fresh wire . No corrosion , anywhere .

A loose connection is worse than no connection .

Re: Vespa Piaggio Grande 79 no spark

She lives! After several hours of horsing around, cleaning carb, sanding/setting points, dressing the spark plug, she fired and I got some gas through it, even took it out for 1/2 mile ride to get everything moving and flowing after sitting since the 90’s. I’m not that familiar with this style of ped. What’s the deal with the brakes, if you put the brakes on does it kill the motor circuit? Thanks

Re: Vespa Piaggio Grande 79 no spark

I’m not

> that familiar with this style of ped. What’s the deal with the brakes,

> if you put the brakes on does it kill the motor circuit? Thanks

.... take a look at myrons page under vespa electrical to gain an understanding of vespa spark issues, just ground the blue wire off the magneto, of course clean and set points.

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