New spark for Old Duc

[Vespa]

My buddy is restoring a '72 GT 750. I have a 2001 ST4 engine in pieces (after severe piston failure). Apparantly it is possible to graft an ST2 alternator to the old bike. Does anyone know if the ST4 alternator can be made to fit the old GT?

cam

[DesmoDog]

I don't think it will, but I'm no expert. There's a lot of information on the swap here:

[Vespa]

Thanks. Passing the info along.


cam

[Rocket Rick]

Hi Cam,
The time to address a problem is when you know you actually have one. Many owners are perfectly happy with the original electrical system. Your buddy should just restore it to stock, especially if it's his 1st restoration attempt. The original 150 watt alternator was adequate, but the regulator didn't put out enough charge if the engine wasn't spun high enough, like might happen if the bike was doddled about the city all the time.
The big secret is to use straight SAE 50 (not Castrol GTX), warm it up at 2-4000rpm, and keep it spinning from 4-7500 once warm. You can spin it higher on top gear top end runs. Oh, and use the correct wattage headlight bulb.
Give 'er some stick!
Rocket