WOW this is a long thread!
I'll add my two cents...
I've built almost thirty bikes now, and have never had a problem with the studs.
I've never had a problem with drilling through the frame.
I DID have the bolt that goes through the frame break once & the engine did what Bruces did. (my fault, I used a cheap bolt)
I didn't have the catastrophic failure that he did because I noticed it immediately when I heard some noise & noticed the pedal was touching the side of the engine.
I was able to ride all the way home with it like that, (I just let the engine rest against the pedal the whole way home.)
These engines are not designed to be used without the pedals.
Removing the pedals puts even more stress on the engine.
I truely think this happened because of builder/ rider error... i.e. mounting the engine that way + over torquing the bolts, removing the pedals, & riding the bike too hard without paying constant attention to the machine while riding.
I'm really glad he wasn't hurt, & I hope he fixes his bike & gets right back on it. (because they are really fun!)
I think we all need to take personal responsibility for the way we build, ride & maintain these cheesy little engine kits. (because they ARE cheesy, & can be dangerous!)
Get back on it Bruce!!