I have been through an ordeal with a power torque engine.
I have a block here that has been bored oversize by 0.40.
All looked good so I built the engine.
It would start easily.
However it would only idle & not rev above that.
It was back firing through the decompressor at times.
Then it would stop running.
I read all the related threads.
Checked all o-rings rebuilt & replaced carby.
Tried all I could think of.
I ended up stripping it back down and putting all the parts on another block with a standard size bore.
I had the same fault, engine would only idle.
Checked and rechecked everything, I was even replacing good o-rings.
I feel stupid but it ended up being a blocked muffler.
Thought I would share this.
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/11/full-4730-8735-zz_053.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/11/full-4730-8736-zz_055.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/11/full-4730-8737-zz_054.jpg)