Markiss

I have the Mfactory LSD in mine now,it's great! What a differnce that madr.

They discussed the reverse gear set up for the bike engine swap in this video along with other points of interest for the swap: https://www.youtube.com/watch?v=jR3T8a44reU

A second vid of it in action: https://www.youtube.com/watch?v=UtA3YT_zohM

+1 on the low torque. Crotch rockets have good HP but low on TQ.
I almost went down the Hayabusa-swap route until I did more homework. 
Also, they rev way higher than a car engine. So you're going to have it screaming like a banshee. I think that would make it annoying as well. But to each their own.
And then no reverse gear. 
So if you'd want around 140hp from an engine, I'd go Vtec. Same HP, higher TQ, less screaming, and reverse gear. 
I did the same Jersey. D16Z6 with the 3.7 final gear trans with brass and carbon syncros and a Mfactory LSD (to eliminate/reduce torque steer) from Synchrotech in Cali. It's in the shop getting tuned and dynod. Cant wait.

Bike engines don't make the torque a car engine will.

I used a D16z6 Honda engine with a factory 3.7 final drive and its perfect for a mini. Mine is turbo.

Yep forgetting to swap the final drive on the 1100 was an issue. Fortunately for me, my buddy had done the swap on his Mini and got the result you did. He had to change his. We got it right on mine. I also changed the left side motor mount bracket to the 850 one, which made fan belt changes easier. We both liked the remote shifter improvement over the magic wand. Being curious, I tried installing the magic wand into the remote and it actually worked, though ridiculously tall. The proper one went in.

I went the 1100 route when I lived in Boise, I found a wrecked Austin America in a field and bought it off the owner, I didn't change the diff out so it was always revving high. I've always liked the 998, pretty much indestructible prob will go that way.
Thanks, Martin.

Why not build out a 998 to is ultimate?
Or go (a bit funky) and do the 1100 route? In my first Mini, it was a nice upgrade from the wee 850.
 Both options have reverse too!

I watched a video of another build in the UK of a conversion kit from Z Cars LTD (I think it was Z-Cars but I can't find it now). I had a great conversation with them today but they have stopped making the kit. The CEO told me that they thought that too many inexperienced builders could be injuring themselves due to poor body stiffening designs and of course torque-steer with 140+ BHP at hand.
Maybe I need to grow up and settle for a nice 998 (my fav over a 1275, although I have them both).

Dan Moffet, I think you're right. I'm pretty sure it was a Mini I originally saw it on, maybe it was this setup?

Periscope!
(10) Classic Mini with a Yamaha R1 build complete time lapse from shell to rolling Episode 1 - YouTube

Martin:

In the photo you posted, that looks suspiciously like a starter motor to the left of the frame around the (exposed!) drive chain. Maybe it is the "go backwards" motor?

In a Mini, I wonder how you'd see around the intake system shown.

Thanks Dean, interesting approach, could be a challenge to find enough real estate in a Mini but much cheaper than a conversion kit.

I saw where someone used a starter motor for reverse. I have no info on it, other than the starter motor was independent from the cars motor. You pushed a button to engage the separate starter motor. With the car in neutral, or clutch pushed in, the car would go backwards when the button was pushed. I wonder what the new Harley trikes use? Check this out, https://youtu.be/TdObULcKL94, https://youtu.be/aMHT2kr3WxY

I guess I'll be calling England tomorrow!