Weed wacker runs backwards

[DeeDubya]

On rare occasions when I re-start my Troy-Built TB90BC it will run in reverse. It has the spring assist start and it kind of recoils and then actually runs backwards. I immediately notice that it won't rev and of course the spool is turning the wrong way. I have to kill it and then restart it. :confused2:
Just wondering if anyone else has had this happen. It's a 2-stroke of course and otherwise has plenty power.

 

[KennyG]

I've never seen one do this, but a two stroke will run backward with no problems except the ignition timing is off. That's why it won't rev. I wonder if your timing is a little off to begin with, making it easier to fire when turning backward.

Interesting side issue: two stroke diesels (without direct injection) run the same forward and backward - it doesn't make any difference.

 

[MikeD74T]

SkiDoo snowmobiles & probably some others run their 2 cycle engines backwards to get the machine to move in reverse. Basically they slow the engine way down & shift the electronic timing to fire very early, kind of like a backfire, then adjust the timing to run in the opposite direction. MikeD74T