It depends, I bought mine, a Hilborn unit, off ebay, real cheap, and if you already have a set for your Honda, it's almost a bolt on, and if you have one of my pump drives on your Honda, I make an adapter for the Yamaha, that makes it a bolt on too, so you're looking at roughly $1200.00 for the first engine, in adapters, and cutting and plating the Yamaha. I haven't tried putting on an Acro pump drive, they are awfully heavy, but it could probably be done. Bob!