The best starter for Giant scale engines (up to 50cc class) is the ALIGN Superstarter STQ 100...
If you do a search on it, you will find numerous sources for them.

They use 3s1p 1900 - 2300 mAh/16c lipo batteries..

I start numerous engines every week, many of them new right out of the box. Starting them by hand gets tiresome. This starter is awesome.
It will easily start our YD-A 56cc engines. It is good for LOTS and LOTS of starts before a charge.

They aren't cheap... but the are most definitely worth the cost. They are about $130 + cost of the battery.

Over the years, I have tried most every starter in the market place. This one is the only one I use now.....

Hey w8ye I had the dynatron setup like yours...... too heavy for me..... honestly, if you ever get the chance go look at the ALIGN.

Cheers
Henry