could not seem to find this answer elsewhere.
when card counters are advantage betting what % of their advantge bets should they win ?
60% ? 65% ? 70 %? More ?

Not even close.

https://blackjackincolor.com/truecount5.htm

Even in extremely high counts your initial bet won't win more than 45% of the time. You do lose significantly less hands though. Much of the edge just comes from getting more blackjacks. Remember card counters only have around .5%-2% edge overall depending on how good the rules are.

In very high counts you can get like a 10% edge on your initial bet, but these are extremely rare unless you're playing single deck, and rare even then. You're still winning less than 45% of hands though.

https://blackjackincolor.com/truecount2.htm

Thanks for the info. Very very hard to believe
The MIT guys won the kind of
Money they did on such tiny edge.
I was gonna guess at plus 5 or
More it had to be at least 60%

I believe at the current universal rules of the game your edge goes up about 1% per every -1 added to the true count. Of course this depends on game rules and isn't an exact number.

I consider blackjack a very exciting game and I never stop getting involved in it. I always try to keep abreast of all the news and follow the players. Perhaps someday I will be able to break some kind of record. If you want to learn how to play or improve your skills - go to the site https://gamblerkey.org/ and read, study.

Off the top of a newly shuffled shoe, when the house has a 0.5% advantage (which is fairly typical, given normal rules), the house actually wins a higher % of rounds than the player (more than the 0.5% advantage would indicate). If blackjack were a truly even money game, a 0.5% house edge would indicate a 50.25/49.75 split. But blackjack is only a pseudo-even money game. Aside from blackjacks, which pay 3:2 (if you find yourself in a game where blackjacks pay only 6:5, leave), the player will also win a higher % of the rounds which go to multiple bets, through doubles and/or splits.

Depending on rules and spread, a card counter will generally have around a 1% edge on all action. During rare fluke counts, you can get a 5% or higher edge, but most of your work is done in the 1.5% to 2.5% range.