IMHO, I like the LA series of engines. Not only are they cheap to buy, they are easy to break in, easy to maintain and if they are treated properly, they will run forever. I still have my .40 LA that I used on my 1st trainer, and it still runs great! Granted, they aren't "barnburners", but they do the job they were intended to do, and that is to provide the end user with something that is reliable and easy to use.