battery isolator, fuse size

the iso i have is a PAC-200. what size fuse before the iso should i use and what size should i use between it and the other battery? do u think dual yellow tops will be enough for 2 kicker 1000.1, 650.4, 250.2, and a 200.4. im running 0/1 ga.kickerL7

OK, do you understand what an isolator DOES? If you are putting an isolator in, why are you asking if two batteries will be enough? Don't use the isolator at all. Wire the batteries in parallel, connect your amps to the positive terminal of the back one, and be done with it. The isolator is a power waster... BUT, if you are BENT on using an isolator, only the battery leads need to be fused, and fused for the ampacity of the wire. #0, or 1/0 (one aught) needs to be fused at NO MORE than 350A. The input lead (or terminal) is isolated, so you don't need to fuse it.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Those batteries won't help much if you havent upgraded your alternator and the big three. have you dont this yet?

so just wire the neg of the 1st battery to the positive of the 2nd battery? the alt has been upgraded to 140 amp. whats the big three?kickerL7

No.  Parallel means positive to positive, negative to negative.  If you do what you propose and series them, you'll get 24 volts and fry something.  I strongly suggest having a knowledgable friend help you or taking it somewhere to get it done.  Read the sticky labeled "How to upgrade the Big Three".My ex once told me I have a perfect face for radio.