I hook up my starter box to 2 x 12 V Yuasa bats in series ... 24 V on the box will kick anyhting over .. and i think i got a stock 550 in there ..

Try this tho ... Get your dremmell and a cutting disc , then cut small grooves along the edge of your fly wheel .. that will give it heaps of grip on your starter box .. that should turn it over .. I do that to my run in fly wheel .. it starts first time every time once pre heated .. hope this helps

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