I've searched and Google'd about this, and yeah there's even a currently active thread on adding a 1000cc top end to an R80. Bear with me here! Locally there is an R80 G/S with a bottom end which went through a bit of a erm… catastrophic failure. My dad and I are looking to do what any poor unsuspecting saps would obviously do and drudge it back to life. Before sinking any cash into this project we've already come up with a few routes of action and I've searched most of our questions out but a few linger. I've read many threads hailing the R80 engine's smoothness and how fantastic it is but many seem eager to replace the cylinders with the Seibenrock 1000 kits, etc. As the bottom end is on this thing is roasty-toasty it'll never be a number matching show queen. That's fine with me, all the more fun to have with it. One of our options I haven't quite mapped out fully is to mate a post-90's r100 engine to the original transmission. I figure this is a good way to avoid the possible valve-seat issues of the 80's which I've read a bit of, sidestep the circlip hoopla as it's an 1981 and get some more power. Is this doable? Are we asking for trouble? Enough bench racing… any suggestions?