[Mr Gazza]

What an absolute pig this is being..!!!

Picking up on the frustration in this thread and trying to think of a useful contribution.

My first thoughts are of "Spark erosion". I have not had any direct experience of this proccess, but I have heard of it working when all else has failed to get broken studs and bolts out of the cases of various Brit bikes in the past.
I'll be honest and say I don't know how it's done. I assume it's somthing like an electric welder, but the arc burns away the chosen item....How deep this will go I don't know, but I reckon it would remove the ends of the bolts so the engine could be removed from the frame ( or vice versa), and then the remaining part of the bolt could be dealt with in a fly press or some such??

On a simillar theme to the Spark Erosion, I though about when your welding rod sticks to the work and very soon turns cherry red up the whole length of the rod...!!

I wondered if a welder could be used in a simillar way to induct heat into the bolts very rapidly wthout heating the ally too much.?

I wouldn't know exactly how to go about that, but I am fairly sure it could be done.

I would definatly take the precaution of removing the alternator coils, pick ups and anything else potentialy at risk from the high current.

Sorry if this sounds a bit off the wall, I am just sensing your desperation...