Yamaha 30 and 40hp are the same motor; differences are ECU and intake restrictor. So if you've seen them with Yamaha 30s you're ok. That motor weighs about 215 lbs.

For Suzukis, the 25/30hp are the same - 3 cylinder that weighs about 175. So if you've only seen them with Suzuki 30s, maybe a Yamaha 40 is too much.

 

Yamaha 30 and 40hp are the same motor; differences are ECU and intake restrictor.

Oh awesome, so you the 40 would probably be fine on there. I had a 40 on a Boston whaler 130 sport but I just know CS tend to be light and didn’t want to have something too big

 

I did the google. JV15 has a hull weight of 517 and a max gross weight of 870. That gives you a working capacity of 353 lbs. Take a 215 lbs motor and you're down to, ummm, 135 lbs. I agree with you that a 40 is technically too big for that hull. Now, if you are smart and trim it right and don't load everyone on the transom, I think it'll work fine.

EDIT: Actually I think that 870 gross weight has got to be passengers only, not the max weight people, motor, gear. So yes, I think it'll be fine. Also the press photos from CS show it with a Yamaha 40.

 

It’s rated for a max of 30hp.