Cub won’t start

[OklahomaCubOwner]

I recently bought a 1948 cub and it had no spark. I rewired the ignition system and replaced the coil, plugs, wires, rotor bug, and distributor cap. I could not purchase points or condenser locally. I cleaned the points and now have good spark. Now it is backfiring and will not start?

[Jim Becker]

A '48 would have originally had a magneto. Is that what you still have? You may have not gotten the rotor back in time. See this thread for some details:
viewtopic.php?f=1&t=113600

[Eugene]

Was the engine running when you purchased the tractor?

Before trying to start the engine, prime the oil pump. And conduct compression tests. Engine is prone to stuck valve(s) if sitting for a length of time.

You need to identify the ignition system, magneto or battery powered, before going any further.

One more post and you can utilize the on site manuals, Quick Links, upper left of this page.

[Rick Spivey]

My experience is that backfiring on these cubs generally means you have the timing out, and usually 180 degrees. Check and triple check your timing.

[Waif]

Yep.
Get all ignition specs in order. Then the timing.
You're closer than you were. But don't know how far off the prior specs were. Like rotor position and other timing components.

[Slim140]

Crossed plug wires maybe? Ask me how I know

[SONNY]

crossed wires are usually the most common thing. and yes it happens to us all !!

[OklahomaCubOwner]

It was converted to 12 volt before I purchased the tractor and had been sitting for about 4 years. I reset the timing (yes it was 180 out) and now my spark issue has resurfaced and getting intermittent spark. The journey continues