I’ve owned the bike for a year and it’s never missed a beat. Last week I started the bike up first kick. Let it warm up. Rode it for a short time and it started to lose power, I could only keep it alive by revving it like hell. My first thought was to clean the carb, I cleaned all the jets with an airline. I also stuck in a new spark plug.

This weekend it was exactly the same, starts ok, gets warm, wants to die.

I’ve checked the spark and it’s very intermittent and when it is there it seems weak. Electronics really aren’t my strong point.

Has anyone experienced anything similer?

 

 

 

I had very similar on my 309.

The most common cause seems to be one of the coils on the stator getting old and breaking down under heat. Having said that, the problem on mine turned out to be the blue HT coil/CDI box that you’ve pictured. Unfortunately there is no way of testing the HT coil. 

The first thing( cheapest tp try ) I would do is put in a new NGK plug gapped @ 0.45mm  this smaller gap will lessen the load on the ignition.Maybe check your chassis earth this will only take a couple of minutes to clean up.

If that does not work I think the next easiest thing to try is swapping out the HT coil / cdi box.

Sounds more like the stator behind the flywheel, you can test the readings with a simple ohm reading test meter, the blue HT coils can be good but there is a lot of cheap copy ones coming in. If the stator hasn't been rewound in the last 10 years or so it is going to need doing soon, I messed around for a while changing one thing then the other, it just disappoints when it play up. Bradford windings I have found the best for the stator and Bill Pye for a black HT coil designed for a Fantic not Vespa!

Steve Goode has the correct coils also , and great service , even over here !

And they mount with 2 bolts ....!

Edited February 23, 201610 yr by axulsuv

Bradford windings I have found the best for the stator and Bill Pye for a black HT coil designed for a Fantic not Vespa!

I've used West Country Windings a couple of times and found them to be good.

The blue coils are original equipment on the later aircooled Fantics. From what I was told when I had problems with mine there are several different versions of this coil for different applications the most common being scooters.

As axulsuv said Steve Goode will be able to sort you one of those.

Thanks for all the advice so far. This is typical, as I have my first trial of the year in under 2 weeks!

 

I think I'll have to go through a list of things in order. Starting with the free things.

Check plug gap

Check earth on HT coil
Check for moisture behind the flywheel
Check stator readings

Change HT lead and plug cap
Change HT coil

I've had a quick look on youtube on how to check the stator, does anyone have the correct readings for this?

Thanks again

Success! 

 

It turned out to be 2 problems. The spark was very weak, so I cleaned up where the ht coil earths to the frame. I also cut a little from each end of the ht lead to make sure there was a good connection. The spark was much stronger than before. But it still died under heavy throttle use.

 

So I stripped the carb out and spent 2 hours cleaning everything meticulously and replaced some o-rings on the choke. The bike fired up after a little while and now seems to run perfectly. I only had 30 minutes at this point, but it seems fine and fingers crossed thats the problem sorted.

 

 

Cheers for all the help and advice, very much appreciated.

Edited March 5, 201610 yr by samwisemcg

Ever get it situated? We are similarly working out a 240Pro no sparker. 

Any pointers from your experience appreciated.