Re: Looking to purchase a 507f91A that is for sale.
Impossible to know for sure like you already know. Good compression is key to a good running motor. Good controls is a plus. How long has it been since the motor was running on a boat? May need a tune up if its been awhile. Spark plugs, fuel filter, carbcleaning inside and out, float adjustment may be needed. Check and or replace gear case oil. Also and a must in my opinion is change the impeller. Many people get a new used motor and soon discover that there motor will not cool the way it should. Changing impeller can fix this problem before it starts. One other is if you do go with the new used motor then you will need a manual for that motor to help with repairs if any. So its a gamble but I do hope a good one for you. Good luck and if you do run into running problems then post it and someone will do the best they can to help.
