Hi, new guy problem with spark on atc110..

[sounddoctorin]

First of all I'm a pro at troubleshooting electronics (mostly musical but I've done a lot of auto also) so I've obviously checked the obvious :-)

I've just tried two coils that both produce voltage on my bench when I just run a diode checker on the primary. Plus I had the original but I went to car coils because I WAS getting more spark and actually had this thing running at idle at one time. However the plug would tend to get fouled if I gave it any gas at all so it absolutely wouldn't accelerate from idle. YET it would start right up and idle.

Anyway somewhere along the way of trying to adjust the carb...I suddenly couldn't get it to fire at all. Finally put my scope back on it and..oh...no spark.

Now the odd thing is I'm getting maybe 20V p-p pulses on the PRIMARY...and the secondaries of both coils measure 10Kohm like they should. But even without a plug in there, my HV probe now gives me absolutely nothing. How bizarre. So I just got another coil and stuck in there... identical result.

Obviously this sounds impossible but what I'm HOPING to find is someone who at least knows what the primary should be showing from the generator. (I also tried holding the plug out where I could see it but no visible spark. Thought maybe my probe got whacky somehow..)

[MonroeMike]

Check here.
http://www.3wheelerworld.com/showthread.php/126529-ATC90-110-125m-(84-85)-amp-TRX125-(85-86)-Service-Data

[tri again]

First of all I'm a pro at troubleshooting electronics (mostly musical but I've done a lot of auto also) so I've obviously checked the obvious :-)

I've just tried two coils that both produce voltage on my bench when I just run a diode checker on the primary. Plus I had the original but I went to car coils because I WAS getting more spark and actually had this thing running at idle at one time. However the plug would tend to get fouled if I gave it any gas at all so it absolutely wouldn't accelerate from idle. YET it would start right up and idle.

Anyway somewhere along the way of trying to adjust the carb...I suddenly couldn't get it to fire at all. Finally put my scope back on it and..oh...no spark.

Now the odd thing is I'm getting maybe 20V p-p pulses on the PRIMARY...and the secondaries of both coils measure 10Kohm like they should. But even without a plug in there, my HV probe now gives me absolutely nothing. How bizarre. So I just got another coil and stuck in there... identical result.

Obviously this sounds impossible but what I'm HOPING to find is someone who at least knows what the primary should be showing from the generator. (I also tried holding the plug out where I could see it but no visible spark. Thought maybe my probe got whacky somehow..)


some sort of ac comes out of the stator coil under the flywheel. and it can also be check for resistance.
service manual
should light up as a clickable link.
and will give you lots of values of different components.
Nice clean grounds and connections are where we seems to start
and nothing wrong with di electric grease.
Spark plugs can get funky within minutes when the run rich.\
I even bought a psark plug sandblaster from HF for like 12 bucks because of all my
misbehaving 90-110's.
The last tiny bit of the plug wire can get corroded and the plug cap can also short internally so
best to check spark right from the wire with no cap.

I cannot believe it but I had a bad ngk out of the box the other day.
That was an old champion trick but sounds like you're close to
the process of elimination phase.
Carbs always need to be cleaned if they've sat a while and nice to
clean the tank too.

Stator output as ac gets changed to dc MAYbe in the cdi if it has one, (some 110's have points) kill sw ground and everything else they say in the service manual.

You'll get it.
We always do.
Please keep us posted since we all need to know the answer.
is a good place to start.