Okay everyone so i was given a 5hp briggs flathead by my uncle. it had a broken crank, so its been sitting on a shelf for the past 6 years or so. Recently, while i was working in the shop at school, i came across an identical engine. so i stole the crank from it, pulled mine off the shelf, and slammed the new crank into the engine. bolted everything up, and without the cover on, turned it over a few times to make sure everything was going to be alright. it turned over easily, good compression, goes through all the strokes without hitting anything. so i put the crank cover back on. All of a sudden it is very stiff to turn over. if i loosen the top bolts on the cover, it turns freely. Anybody have any idea what is causing this?
BTW the reason it needed a new crank is because it used to be a pump motor, with no hole drilled in the crank, and someone drilled a hole and put it on a gokart, but their hole was off center and it snapped the crank off.
Any help is appreciated, as i would like to build this engine and put it on my gokart.