NO SPARK HELP!

NewbieNed

New Member
Joined
Jul 21, 2018
Messages
5
I got this motorized bike 8 months ago and its been a nightmare, one thing after another, and i havent been able to get it started once.

Now theres no spark and ive tried everyyhing i can think of

I tested the cdi with a multimeter, tested the plug, and still, no spark.

I dont know what to do, please help.

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crassius

Well-Known Member
Joined
Jul 23, 2012
Messages
4,575
is your blue wire spliced into that green one? you have the kind of mag that uses the white wire as a spare for the blue, so what is that going to?good ground from black to motor head?

if mag is good and holding plug in hand does nothing, you probably need a new CDI as those can not be tested with a multimeter
 

KCvale

Motorized Bicycle Vendor
Joined
Apr 18, 2010
Messages
3,518
My troubleshooting procedure is simple these days.

Disconnect everything.

Ohm the black magneto wire to a head bolt, it should read a dead short.
If not, check the ground tab on the magneto.
Note:
The new skyhawk CDI's have no white wire, ground is the lower connector but it has a wire from it to ground.

Old style mags with a white wire have a tab out of the mag that solders directly to the mag base and they can come loose, just hold it down and re-solder.

Ohm the magneto from the black and blue wire, 320-380 ohms is ideal, an open or dead short means a bad magneto if the wires are connected.

Ohm the CDI in the 10K-20K scale.
Red+ meter probe to CDI black wire.
Black- meter probe to the spark plug cap.
You should get about 6.9K ohms.

If not it could be a bad wire or cap.
Unscrew the plug wire at the cdi, use pliers or even cut it off and dig the junk out if need be and do the same test above again to the cable screw on the CDI.
If that works get a new wire and plug cap, if not you have a bad CDI.

If all of that is good there is only one thing left, the magnet.

That was indeed the problem with this repair on a new build with a 2014 gasbike.net front page engine kit.

When you pull the 4 bolts out of the magneto mount it should slam itself against the magnet, I mean to the point where it is hard to even get your first bolt in.
A weak magnet that lets you move the mag around pretty easily is not strong enough to create a spark which is what this repair had.

Magnet replaced, problem solved and my repair is done.
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
709
My troubleshooting procedure is simple these days.

Disconnect everything.

Ohm the black magneto wire to a head bolt, it should read a dead short.
If not, check the ground tab on the magneto.
Note:
The new skyhawk CDI's have no white wire, ground is the lower connector but it has a wire from it to ground.

Old style mags with a white wire have a tab out of the mag that solders directly to the mag base and they can come loose, just hold it down and re-solder.

Ohm the magneto from the black and blue wire, 320-380 ohms is ideal, an open or dead short means a bad magneto if the wires are connected.

Ohm the CDI in the 10K-20K scale.
Red+ meter probe to CDI black wire.
Black- meter probe to the spark plug cap.
You should get about 6.9K ohms.

If not it could be a bad wire or cap.
Unscrew the plug wire at the cdi, use pliers or even cut it off and dig the junk out if need be and do the same test above again to the cable screw on the CDI.
If that works get a new wire and plug cap, if not you have a bad CDI.

If all of that is good there is only one thing left, the magnet.

That was indeed the problem with this repair on a new build with a 2014 gasbike.net front page engine kit.

When you pull the 4 bolts out of the magneto mount it should slam itself against the magnet, I mean to the point where it is hard to even get your first bolt in.
A weak magnet that lets you move the mag around pretty easily is not strong enough to create a spark which is what this repair had.

Magnet replaced, problem solved and my repair is done.
I notice the ohm reading on coils vary slightly with ambient temps (bench testing) , do you find the same?
 

crassius

Well-Known Member
Joined
Jul 23, 2012
Messages
4,575
yes, a lot depends on how well solder was applied, and quality/quantity of wire used - standard reads are 250, 350, & 490 - but these can vary by about 40ohms +/-
 

NewbieNed

New Member
Joined
Jul 21, 2018
Messages
5
Thank you all for help

Im going to order a magneto loop and eventualy a cdi
I will make an update once i correctly install the parts
 
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