i just installed a new chain on my 425 magnum and when the machine is off the chain is at its recommended tightness bout an 1 1/2 maybe a little less when i turn the machine on and put it in high the chain tightens up but when i put it in reverse or turn the mahince off it goes loose again. Any ideas?

 

bump

 

my guess is because the forward pressure from the gear being engaged tightens it... and if its in reverse... it would make sense for it to loosen back up.