Another Doo question

[LeonDude]

Just read the post by Humpty Dumpty about his doo springs failing, so now I'm wondering - what would happen if the spring has failed and you release the bolt for the service and the chain goes all slack - and you then start the bike after tightening the doo again?
Will the chain come off it's guides and eat up your engine or will the engine just run rough because the balances no longer works?
Obviously no damage due to an ingested Doo, but what other damage?
And if it did happen, what would the symptoms be?

 

[Groenie]

 

[RobCrouch]

 

[lecap]

 

[GreenMachine]