Linkert m18 tuning question and backfiring question

[rustforsale]

Hi. I have a 1950 WL with a Linkert m18. Every single tech book or guide or whatever is telling me to tune the harley carb differently. They are general not specific to the m18. One book says to carb tune turn both needles Down, turn the low out 5 turns and the high out 1.5 turns. One book says start with the low 2 turns out and the high 1.5 turns out to start the tuning process.

So what is it? I can't seem to stop my bike from back firing when I snap the distributer retard way. I've just adjusted all the valves. I just put in a new condenser. New points. New timing set perfectly for the points. Point gap perfect. I was wondering maybe it's the coil?

Is there ever a situation when the spark isn't strong enough and unburied gas is being ignited in the muffler ? Is that a scenario? With a weak coil? How do you test a coil anyway?

Thanks everyone
Dave

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[T. Cotten]

Dave!

The first diagnostic is always to test for vacuum leaks:
http://virtualindian.org/11techleaktest.html

Then the rest will be easier to sort out.

When all things are in order, you can start at 1 1/2 turns on the highspeed, and 3 1/2 turns on the low, and tune from there.

....Cotten
PS: If you retard your timer after starting, and then give it gas, a report from the muffler is common. It is normal to leave it advanced.

[rustforsale]

Should have included that yes I have done a vacuum leak check. Thanks!