spark plug shocks but no spark, anyone had this before?

trying to get a tomos a3 parts engine going for a build. ignition is running me in circles. i had it sparking at one point then i lost it again. now it makes voltage but its took weak to jump the gap, shocks you but no spark.

last time i had this problem on a different renovation, it ended up being a slightly corroded points wire connection (tiny nuts on the points) in the stator.

2-wire idm labeled stator(should i change it to three and ground the internal coil externally?)

ive replaced the internal coil, points, and condenser. point gap is .020". i have the condenser positive hooked to the internal coil and the points wire, this all runs to the external coil positive lead. all the grounds and wires are getting continuity, ive cleaned it all multiple times. no killswitch hooked up

what voltage should i be seeing on the hot wire that runs to the spark coil? i get like 3-5 volts when i kick it over.

with the external coil connected, probing the plug boot without a plug in it, i get almost 9volts (still seems way low right?).

any other tips/ tests i can do to find my fault? try an external coil off a running bike see if that works?

Re: spark plug shocks but no spark, anyone had this before?

> k blum Wrote:

> -------------------------------------------------------

> trying to get a tomos a3 parts engine going for a build. ignition is

> running me in circles. i had it sparking at one point then i lost it

> again. now it makes voltage but its took weak to jump the gap, shocks

> you but no spark.

>

> last time i had this problem on a different renovation, it ended up

> being a slightly corroded points wire connection (tiny nuts on the

> points) in the stator.

>

> 2-wire idm labeled stator(should i change it to three and ground the

> internal coil externally?)

>

> ive replaced the internal coil, points, and condenser. point gap is

> .020". i have the condenser positive hooked to the internal coil and the

> points wire, this all runs to the external coil positive lead. all the

> grounds and wires are getting continuity, ive cleaned it all multiple

> times. no killswitch hooked up

>

> what voltage should i be seeing on the hot wire that runs to the spark

> coil? i get like 3-5 volts when i kick it over.

>

> with the external coil connected, probing the plug boot without a plug

> in it, i get almost 9volts (still seems way low right?).

>

> any other tips/ tests i can do to find my fault? try an external coil

> off a running bike see if that works?

3-5 volts to coil is normal. The ignition coil is likely bad

Re: spark plug shocks but no spark, anyone had this before?

Of course try a know good coil. i think to jump a spark plug gap its gotta be 20k volts or so. Make sure the gap isn't too wide as that will make it hard to jump.

Did u ground the other side of the coil?

Re: spark plug shocks but no spark, anyone had this before?

♣Slew Foot♣ /

Rewire the tail.

Ground tail to frame the safety override for the points. The resistor block in the tail maybe cracked bulbs? Bad kill or the regulator overage gnd it grounded too close to ht ground.

...

Re: spark plug shocks but no spark, anyone had this before?

Be sure the stator coils are close enough to the flywheel , without touching .

.010" usually does the trick .

Re: spark plug shocks but no spark, anyone had this before?

> ♣Slew Foot♣ Wrote:

> -------------------------------------------------------

> Rewire the tail.

>

> Ground tail to frame the safety override for the points. The resistor

> block in the tail maybe cracked bulbs? Bad kill or the regulator overage

> gnd it grounded too close to ht ground.

>

> ...

Yeah good point with a possible bad tail/brake light ground.

Re: spark plug shocks but no spark, anyone had this before?

If it is a coil with two primary terminals make sure the #1 terminal goes to the points and the #15 goes to common (ground).

Re: spark plug shocks but no spark, anyone had this before

ok got it sparking with the external coil from my main tomos.

thanks guys. i was using a new coil off ebay but here's my hypothesis and what happened...

rebuilt the engine as usual.

tested it for spark, makes loud electrical pop get bright spark then nothing.

i take look at the stator, the coil is scratched and shorted and i didnt notice before.

get new internal coil installed, test everything, no voltage, trace it to the condenser (which was brand new) apparently now blown up from the shorted coil. new condenser, get voltage but no spark. now i swapped a working ignition coil and everything works.

tldr: apparently shorted internal coils can fry condensers and external coils? thats all i can come up with.

thanks again, good knowledge dropped in the thread regardless (edited)

Re: spark plug shocks but no spark, anyone had this before

Dirty30 Dillon /

As note, you should NEVER meter the output side of the HT coil. The voltage is way higher than most DMM's can handle and often they will just fry the meter as even a fast blow fuse in the meter is not enough to break before the ~15k V whacks the circuit board.

Re: spark plug shocks but no spark, anyone had this before

makes sense thanks for the tip, mine didnt blow luckily.

Re: spark plug shocks but no spark, anyone had this before?

♣Slew Foot♣ /

If you have a resistor cap do not use a resistor plug .

Peeps would have a bad tail ground and bypass the safety by using both a resistor cap end plug.

Re: spark plug shocks but no spark, anyone had this before?

note: ebay coils are a waste of time and money

Re: spark plug shocks but no spark, anyone had this before?

> pat splat Wrote:

> -------------------------------------------------------

> note: ebay coils are a waste of time and money

Hmm , I bought a 6 dollar ignition coil that's been working fine for the last 11 years through ebay .

Maybe I better find an upgrade . ;)

Re: spark plug shocks but no spark, anyone had this before?

> P D Wrote:

> -------------------------------------------------------

> > pat splat Wrote:

>

> > -------------------------------------------------------

>

> > note: ebay coils are a waste of time and money

>

> Hmm , I bought a 6 dollar ignition coil that's been working fine for the

> last 11 years through ebay .

>

> Maybe I better find an upgrade . ;)

yeah ill trade you three new garbage ones for your one good anytime.

Re: spark plug shocks but no spark, anyone had this before?

> pat splat Wrote:

> -------------------------------------------------------

> yeah ill trade you three new garbage ones for your one good anytime.

Ha . Bet you would .

Seems I've always been fortunate when buying cheap China stuff , except for a turn signal flasher I bought years ago . That dang flasher only works when the bike is running . But , maybe the dead battery has something to do with that .

I guess I shouldn't complain , as that 10 dollar China battery lasted about 6 years . Maybe it was only 8 bucks . ;)

Re: spark plug shocks but no spark, anyone had this before?

^^maybe try buying something in the last 10 yrs for comparison.

Re: spark plug shocks but no spark, anyone had this before?

Richard Eberline /

You can test all four items, HT coil, internal coil, condenser and points with a ohm meter.

Re: spark plug shocks but no spark, anyone had this before?

> pat splat Wrote:

> -------------------------------------------------------

> ^^maybe try buying something in the last 10 yrs for comparison.

Ha . Being as everything changes , always . You might have a point .

Although , the things I've bought from China in the last few years have all had good form and function .

Heck , even the supposed name brand stuff is made in China these days .

Example : I just bought and installed new front wheel hubs for our old Envoy . Real Timken brand , not copies or fakes . More expensive and very good quality , but , guess what ... Made in China .

Maybe it just depends on QC ? ;)

Re: spark plug shocks but no spark, anyone had this before?

Indeed - companies will build to the specification the importer requests, so if they have a very wide tolerance range they will manufacture to the advantage of their profit margin (ie cheapest as possible), also 'name brands' have same manufacturing procedures which are profit oriented plus QC to ensure the products conform to the requested specifications.

> P D Wrote:

> -------------------------------------------------------

>

> Ha . Being as everything changes , always . You might have a point .

>

> Although , the things I've bought from China in the last few years have

> all had good form and function .

>

> Heck , even the supposed name brand stuff is made in China these days .

>

> Example : I just bought and installed new front wheel hubs for our old

> Envoy . Real Timken brand , not copies or fakes . More expensive and

> very good quality , but , guess what ... Made in China .

>

> Maybe it just depends on QC ? ;)

Re: spark plug shocks but no spark, anyone had this before?

Yes, it is all quality control.

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