My make &break wont run

[PeeJay]

Hello,
I am a retired auto technician and have worked for 40 years in the auto industry, most recently as a Master Toyota Technician. I know engines and what makes them tick. That being said…..
I recently built a freelance 1 cyl. make and break engine. It is a 1” bore and 1” stroke. I purchased the TIM-6 ignition system. I decided to use this because it eliminated points and condenser and for size reasons, that made sense. I assembled the electronics and tested everything as per the instructions, and all is good. The system was installed onto the engine with the magnet on the cam gear and carefully aligned with the hall sensor which is mounted to a pivoting arm so as to be able to adjust the timing.
To make a long story short…. I can’t make this engine even pop. I’ve tried 3 different fuels, 2 different spark plugs, made 2 different versions of carburetors, and now has a carb off a model airplane engine. I tried priming through the spark plug hole and even tried starting fluid “ether” to no avail.
With the spark plug removed and grounded it shows a good spark. I mounted the LED timing indicator so as to be visible and the timing is perfect. Compression is good and its getting fuel. If I got even a hint of a “trying to fire” or a pop on ignition I would try to isolate a problem. BUT… I can’t get it to show any signs of ignition.
Is there a possibility of a bad coil? I tested the primary side to about 1.2 ohms and the secondary side is around 6.4K ohms.
Could it not be firing under compression? There’s no way to test that. The TIM-6 seems ok. It will jump a spark more than 1/4”. I’m stumped.
I thought I’d write the forum to see if you could shed some light…. I need some help.

See the photo of my engine.

Thanks,
Pat Janson
pjanson@maine.rr.com

 

[tq60]

Basic ic troubleshooting

Compression
Spark
Fuel

Need all 3, you know that

Weak point is more voltage required to spark under compression.

You have correct timing and spark with plug out, test 1 is place plug in but use another plug or something to indicate spark and connect hot lead to this, place it somewhere you can see.

Turn by hand and check to see if you see spark when it is on compression.

Is the plug wet from fuel?

Wet could be shorting, dry could be no fuel in cylinder.

If spark at right time then just turn the plug a couple turns, just enough to hold it but let air out, this removes the compression, If it fires then your coil is too low of voltage.

Use your ic skills to troubleshoot, problem will likely be simple



Sent from my SM-G781V using Tapatalk

 

[PeeJay]

Thanks for this input. I've checked all 3 several times all is good..... I'm missing something.
I do like the loose plug test.... never tried that. I will do that.
Thanks, Pat

 

[Alcap]

Do you see movement at the intake valve when your spinning the engine over ?

 

[PeeJay]

Yes, very slightly, and I can hear the "burp" on the intake stroke.
I was thinking of trying a weaker spring on the intake valve to see how that reacts.
Thanks for the response.
Pat

 

[markba633csi]

Compression and timing are the two things I would look closely at
-Mark

 

[PeeJay]

Compression feels OK, and timing is right at TDC.
Thanks
Pat

 

[JRaut]

You’re not spinning it backwards or anything like that, right?

 

[PeeJay]

Aww come on.......

 

[markba633csi]

Check that there are no UFOs nearby- engines tend to stop when they show up