I have a 2015 kart that we have been running SA motors on, I went to a big block 390 and cant keep a chain on now, any ideas on what it could be? Could it be axle flex, chassis flex, I use lock collars on the frame to keep the motor mount from moving so its not that. I ran without a jackshaft and slung the chain several times and now with the Burris style jackshaft it comes off the jackshaft gear to the rear sprocket.