Looking at buying a 1987 bass tracker pro 16 with a 35 horse mercury outboard I wanna know if these are good motors this owner bought the boat in the spring and hasent done much maintence to it since he bought it. It sounds as tho the previous owner may have but can’t be certain. He wants 3900 do u think this is a good deal is the motor any good?

Is that make, year and model a good motor Yes.

Is it going to be reliable, my crystal ball is not working anymore.

Depends on how much it has been used and was maintained. 

I would recommend having someone that's good with outboard motors go with you to check it out and do a compression check. 

When I buy a used outboard, I don't put one in use until I have serviced it, changed the gear oil and install a new water pump.