OP
UTC

Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
 
Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
UTC quote
I just bought this 74 Primavera 125 and barely made it around the block before the spark stopped.
It was running great. Started on the first kick, shifted, accelerated, and stopped reasonably well.
I was having a blast on my first run around town and it just died.
I confirmed no spark, no power to the coil. The small coil wire goes into a small junction box behind the kick start. There it connects to wires going to the points and one purple wire going forward to the ignition switch behind the headlight.
I have power to the ignition switch from the battery.
Turning the key on does not put power out to the purple wire previously mentioned which heads back to the junction box.

Questions: should the ignition switch, when on in either position one or two, give power to the purple wire and thus the coil and points?
And, can I run a hot wire directly from the battery to the coil and points and try for spark that way?
Thanks
Desperate To Ride!
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@xantufrog avatar
UTC

Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: UTC
Posts: 8892
Location: Atlanta, GA
 
Moderibbit
@xantufrog avatar
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: UTC
Posts: 8892
Location: Atlanta, GA
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Moved to Not-So-Modern
@socalguy avatar
UTC

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7157
Location: So Cal
 
bodgemaster
@socalguy avatar
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7157
Location: So Cal
UTC quote
Welcome to the forum. To answer your questions:
Quote:
... should the ignition switch, when on in either position one or two, give power to the purple wire and thus the coil and points?
No, the purple wire is a “kill” - when the key is in the off position, the purple wire shorts the current from the ignition coil to ground instead of to the spark plug.
Quote:
And, can I run a hot wire directly from the battery to the coil and points and try for spark that way?
No, don’t do that. You’ll fry the ignition coil.

Start simple. Could be a fouled plug. Put in a new one.

If that doesn’t work, check for a loose connection between the red wire and the coil.

If still no spark, try disconnecting the purple wire.
OP
UTC

Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
 
Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
UTC quote
Thanks for the tips. Shouldn’t there be 6V to the coil when the key is on?
@v_oodoo avatar
UTC

Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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Posts: 9629
Location: seattle/athens
 
Style Maven
@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
Joined: UTC
Posts: 9629
Location: seattle/athens
UTC quote
Nope, the coil gets timed pulses from the stator. Your battery is just there to power lites when the motor is off per DOT regs.

Try disconnecting the kill wire at the junction box, it may be shorting to ground.

Try hooking a small LED to the wire going to the coil with the purple disconnected. If it blinks when you kick it, your coil may be bad. You already did check for spark by grounding the pulled plug and kicking, right?
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5150
Location: Oceanside, CA
 
Veni, Vidi, Posti
@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5150
Location: Oceanside, CA
UTC quote
Toddfiebig wrote:
Thanks for the tips. Shouldn’t there be 6V to the coil when the key is on?
No. The battery only powers the horn, tail light and brake light on those Primaveras. DOT required stuff.

The ignition is purely the stator, points, HT coil and spark plug. Like SoCal says, swap the spark plug and ground the bottom of the plug while you kick. See if you can get spark. After that, check the points gap and then start looking at the stator wire condition.
OP
UTC

Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
 
Lurker
1974 Vespa Primavera 125
Joined: UTC
Posts: 4
Location: White Salmon, WA USA
UTC quote
Is it hard to take off the fan/fly wheel off if I need to get in there and take a look around
@sdjohn avatar
UTC

Johnny Two Tone
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
Joined: UTC
Posts: 8555
Location: San Diego, CA
 
Johnny Two Tone
@sdjohn avatar
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
Joined: UTC
Posts: 8555
Location: San Diego, CA
UTC quote
your engine should have a flywheel nut with flange, which pushes against a circlip in the flywheel as a puller. with this setup you won't need a special tool to pull the flywheel but the circlips wear out sometimes or go missing.
@108 avatar
UTC

Ossessionato
V range 50s
Joined: UTC
Posts: 2413
 
Ossessionato
@108 avatar
V range 50s
Joined: UTC
Posts: 2413
UTC quote
MJRally wrote:
No. The battery only powers the horn, tail light and brake light on those Primaveras. DOT required stuff.

The ignition is purely the stator, points, HT coil and spark plug. Like SoCal says, swap the spark plug and ground the bottom of the plug while you kick. See if you can get spark. After that, check the points gap and then start looking at the stator wire condition.
Random question, always wondered...

Does the battery power the headlight?
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5150
Location: Oceanside, CA
 
Veni, Vidi, Posti
@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5150
Location: Oceanside, CA
UTC quote
108 wrote:
Random question, always wondered...

Does the battery power the headlight?
Not on any two stroke Vespa I've seen. Those have the headlight run off the lighting coils.

As far as the moderns go, 2005 LX's and newer Yes. ET2's are a no. I dont have any experience with ET4's but i'd guess no.
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