Super Tigres are fine engines. I have two 90's and both run superbly. I believe that for the money they can't be beat. They do take a little breaking in and are a wee bit finicky on the adjustment. But once they are broken in and properly adjusted they are like a well known bunny, they "just keep going and going and going......"
Buy a Super Tigre 60 or 90 and you can't go wrong.
Regards,
doubledee