new motor wont start

[blckwlfny1]

hi guys,
im posting this here because im pretty sure its an electrical problem.
First off, i am using a morini clone in my build; I just installed this brand new..."out-of the -box" ktm-50 motor:

http://motomx.com/ktm50_adventure_engine.html

it is 49cc and has a reed, and comes with the appropriate curburetor tuned to it. I have an expansion chamber and a muffler

dont ask me about tuning it because:...IT WONT START...I MEAN NOT EVEN A SPUTTER....NOTHING!...just the sound of the piston pumping air.

its getting fuel, im using new gas and good yamaha 2-stroke oil at the recommended 40:1 mix, head compression is fine.
to eliminate the possibility of a fuel issue, starter fluid was tried, but it didnt work.
the spark doesnt seem great and it is inconsistent. i have checked the coil, stator, and flywheel magnet and these parts (according to two repair shops) are putting out the right resistence and power,
I changed the ground, changed all of the above components and replaced them with (other) new components. I changed the plug and the wire. I gapped the plug to about .20 and then .30
I cleaned the magnets and stator faces and blew any debris out of the ignition case with pressurized air. checked the gap between the magnet and stator faces. its about the thickness of an index card.
it still wont start.
....correction it started ONCE with absolutely ZERO effort....surprised the **** out of me!...turned right over like it was supposed to...no starter fluid. no choke. it ran like a top. i let it run for about 3 minutes and, thinking i had the problem solved, i foolishlly shut it off....and it wont start again.

This motor has 2 motorcycle repair shops stumped

can someone help me?...pleeeeeease!

 

[socialdistortionkid]

To make a 2 stroke run it needs 3 things: Fuel, air and spark

Since you said you just bought the engine i would be on the phone with the seller. State the problem and if they dont offer a replacement ask for your money back. But it would be easier to just be shipped a new engine than diagnosing this one.

 

[Bikeguy Joe]

I agree with SDK, except for one thing- You need fuel, air, spark (at the right time) and compression.

Send it back!

 

[BigBlue]

Could be your timing is off or your CDI. Disconnect any kill switch.

http://www.dansmc.com/electricaltesting.htm:

Remember, the ohmmeter may have some internal resistance, usually .5 ohm. Hold the ohmmeter leads together to find out what that resistance is and subtract it from your test readings. Take the readings when the part has warmed up to 70 degrees or so.

When you check for spark, the spark must jump at least 1/4" (.250") or more outside the engine. Just laying the spark plug in the plug cap, on the cylinder head, and getting a spark across a .030" gap is no good. It takes a lot more power to jump a gap under compression in the engine then outside the engine under no compression pressure. Also, if it's electronic ignition, you must spin the engine to at least three or four hundred RPM. Any less and the anti kick back circuitry in the CDI black box kills the spark.

Good Luck,

Chris
AKA: BigBlue