long ago engines were overbuilt and for the time lasted a long time. a 36 hp VW would last years and some are still around. but advance the timing too much [i time by ear] don't adjust the valves and these well built robust low hp motors were not long for this world. now these cheep china motors come apart on their own with out any help from hi-compression hi-rev's alot of them self destruct on their own. i wonder if the russian motors were built better? too bad japan didn't make them.