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Enthusiast
2005 Star Dlx - VMC 187ccm
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2005 Star Dlx - VMC 187ccm
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UTC quote
Hello. I'm installing a New ignition from VMC but it doesn't start. I'm having Backfire every 3 or 4 start attemps.

Everything is set as the manual says. I have power in the sparkplug.

Anyone have this ignition kit ?
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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@chandlerman avatar
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UTC quote
backfires usually mean your timing is too advanced. Have you strobed it to see where it's at?

Marks on cases and stators mean nothing. Finding TDC and checking with a timing light are the only timing measurements that matter.
OP
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Enthusiast
2005 Star Dlx - VMC 187ccm
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Location: Venezuela
 
Enthusiast
2005 Star Dlx - VMC 187ccm
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Location: Venezuela
UTC quote
chandlerman wrote:
backfires usually mean your timing is too advanced. Have you strobed it to see where it's at?

Marks on cases and stators mean nothing. Finding TDC and checking with a timing light are the only timing measurements that matter.
I have The strobe lamp but how do i use if the vespa doesn't start at all? I got backfire by kicking the pedal trying to start. I had moved the stator plate 4mm backward and forward from the initial position to see if the engine runs but it doesn't Crying or Very sad emoticon
@chandlerman avatar
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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@chandlerman avatar
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you can remove the spark plug and ground it against the case, then spin the flywheel with a socket in a drill. That'll get you enough sparking to get a rough idea of where your timing is at. It's a slightly tricky move since the drill will torque right out of your hands and possibly injure you, so be careful while you do it.

Looking at the picture of your stator, I wouldn't be surprised if it was too advanced. I usually have mine turned as far clockwise (retarded) as I can get them, and frequently have to extend the slots. You're in the center of the righthand slot, which to me suggests your timing is probably super-advanced.

Also, post a picture of your wiring from the stator to the CDI, although if that were incorrect, I wouldn't expect you to even get a backfire.
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Enthusiast
2005 Star Dlx - VMC 187ccm
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Enthusiast
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UTC quote
chandlerman wrote:
you can remove the spark plug and ground it against the case, then spin the flywheel with a socket in a drill. That'll get you enough sparking to get a rough idea of where your timing is at. It's a slightly tricky move since the drill will torque right out of your hands and possibly injure you, so be careful while you do it.

Looking at the picture of your stator, I wouldn't be surprised if it was too advanced. I usually have mine turned as far clockwise (retarded) as I can get them, and frequently have to extend the slots. You're in the center of the righthand slot, which to me suggests your timing is probably super-advanced.

Also, post a picture of your wiring from the stator to the CDI, although if that were incorrect, I wouldn't expect you to even get a backfire.
Wiring
Wiring
Moved to the end of the slot (retarded) and got backfire. I going to try to spin the Flywheel with a Drill and see
Moved to the end of the slot (retarded) and got backfire. I going to try to spin the Flywheel with a Drill and see
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UTC quote
That wiring don't look correct.

The blue wire from stator is for spark and connects to cdi like you have it. BUT green wire from scooter harness should be kill switch and connected to stator blue wire at the cdi. Use that other end of the yellow wire on cdi to connect to green wire.

White wire from stator is lighting wire and should go to yellow wire from scooter harness. It seems that white wire is connected to ground.

Black wire is ground and should go to motor case like you have it but only connected to other ground wires. No other type of wire should be connected to the ground wire. It seems that ground is connected to your kill wire.

Pull out a mutimeter to confirm the wires I mentioned are correct as I'm trying to connect your pic with the diagram above.
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Lucky
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I rotated and translated the wiring diagram to make it more helpful here.

To troubleshoot, start by isolating the circuit.

Disconnect the second yellow (kills switch?) wire along with the ground wire back to the wiring harness.

The only wires that should be connected are the blue and black wires from the stator to the CDI.

That will remove any other electrical issues you may need to chase down. It should
spark consistently when tested.

Assuming it fires consistently, you can now work on setting the timing. If it won't run, remove the spark plug and with TDC well-marked, even if you only get a flash or two kicking it over, you should be able to get at least an idea of where the timing is set. Based on that, do a rough adjustment and repeat until successful.

The first round or two are kind've trial and error, but if you're methodical, you'll get there.

Once it's running, you can worry about the rest of the electrical.
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
OP
UTC

Enthusiast
2005 Star Dlx - VMC 187ccm
Joined: UTC
Posts: 85
Location: Venezuela
 
Enthusiast
2005 Star Dlx - VMC 187ccm
Joined: UTC
Posts: 85
Location: Venezuela
UTC quote
chandlerman wrote:
I rotated and translated the wiring diagram to make it more helpful here.

To troubleshoot, start by isolating the circuit.

Disconnect the second yellow (kills switch?) wire along with the ground wire back to the wiring harness.

The only wires that should be connected are the blue and black wires from the stator to the CDI.

That will remove any other electrical issues you may need to chase down. It should
spark consistently when tested.

Assuming it fires consistently, you can now work on setting the timing. If it won't run, remove the spark plug and with TDC well-marked, even if you only get a flash or two kicking it over, you should be able to get at least an idea of where the timing is set. Based on that, do a rough adjustment and repeat until successful.

The first round or two are kind've trial and error, but if you're methodical, you'll get there.

Once it's running, you can worry about the rest of the electrical.
The job is done!!!

The wiring diagram from VMC it's OK. It was fine. The problem was the initial position that is in the Manual. I checked the Timings with the Drill and the lamp and it was waaaaaaaay advanced as You said. Something like 80 o 90°

The ignition is 1.4kg without the aditional weight. I had choose the one with 820grs for a total weight of 2.2kg. Time to test

Thanks for your help chandlerman

https://youtube.com/shorts/mBlyjLsE_bA?feature=share
I was hurry and didnt take pictures , but the ignition coil was right in the green box for 23° :mad:
I was hurry and didnt take pictures , but the ignition coil was right in the green box for 23° :mad:
@chandlerman avatar
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Lucky
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Awesome! It sounds great and looks like it's gonna be a ton of fun to ride
⬆️    About 1 month elapsed    ⬇️
OP
UTC

Enthusiast
2005 Star Dlx - VMC 187ccm
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Posts: 85
Location: Venezuela
 
Enthusiast
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Location: Venezuela
UTC quote
Guys.... I got a Question.... It's posible the engine starts and be on 23° BTDC with the stator placed 180°. I've been looking many variable ignition Kits , and the ignition coil is always in the low side of the carter. Mine is in the Upper side.

But , with the strobe lamp, the Timings are good, 23° and retards 8° just fine
@finyoshi avatar
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UTC quote
That is possible. If I remember correctly, these ignitions give two sparks per revolution.
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Enthusiast
2005 Star Dlx - VMC 187ccm
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Posts: 85
Location: Venezuela
 
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2005 Star Dlx - VMC 187ccm
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Location: Venezuela
UTC quote
FINYoshi wrote:
That is possible. If I remember correctly, these ignitions give two sparks per revolution.
Ohhhh... Thats correct. My tach was set 1R2S to work . So, in that case, being 2 sparks per rev , is OK if i let how is actually set ? or must try to adjust the Timing with the ignition coil downside
@108 avatar
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Ossessionato
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UTC quote
Could be a chance you could run the engine in reverse!

Not that you'd want to do that…

Yeah, I see that most of the time the pick up is on the bottom…

Possible to switch the position?
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OP
UTC

Enthusiast
2005 Star Dlx - VMC 187ccm
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Posts: 85
Location: Venezuela
 
Enthusiast
2005 Star Dlx - VMC 187ccm
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Posts: 85
Location: Venezuela
UTC quote
108 wrote:
Could be a chance you could run the engine in reverse!

Not that you'd want to do that…

Yeah, I see that most of the time the pick up is on the bottom…

Possible to switch the position?
Done. I'd 180° turn , set the Timing to 23° with strobe and works fine. I think it can be in both positions. Will test like this with the pickup/ignition coil in botton and see how Performs.

Thanks
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mendozaram wrote:
Done. I'd 180° turn , set the Timing to 23° with strobe and works fine. I think it can be in both positions. Will test like this with the pickup/ignition coil in botton and see how Performs.

Thanks
Hope it goes smooth!
@chandlerman avatar
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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UTC quote
Glad you got it going!

A few thoughts in the aftermath...

If it was assembled correctly, you'd only be able to install it correctly because the lower left screw's slot is inset closer to the center than the other two.

But...that assumes the coils are not installed upside down, which would put them 180 from where they should be.

Thus, it's possible to install the coil onto the stator plate upside down and thus get the pickup 180 from where it should be.
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