Hi!
If Horizon only could use the same name for their engines the rest of the world use, MVVS!

I assume you have the older ignition that looks like this, new to the left.
The older Vlach ignition system runs on 4,8V-6V.
The new one 6-8,4V.

Of course you must use a clunk in the tank! How could the engine/carb otherwise get fuel???