Here is your chance... https://seattle.craigslist.org/see/mcd/d/las-vegas-1992-honda-nr750-finance-it/7182632753.html A little deep for my pockets...
A motorcycle that answered a question never really asked. While a great "look at what we can do!" project, it's a technical dead end.
Got one...didn't pay nearly that much for it and it serves the same purpose that one would. I can sit here and look at it for a lot less money.
Gas-ported pistons or rings might have solved the combustion sealing question. As to the ad, it states none were imported to the States. Not true. I had an opportunity to buy one that was in the crate. Located at a Honda warehouse somewhere in the Carolinas, the dealer woulda let me have it at cost sometime in the mid-'90s. I didn't have the $60k+. Never checked back on it since.
Doesn't seem all that rare/special. Iconic Motorbikes has two of them for sale. One with 3km: https://iconicmotorbikeauctions.com/auction/1992-honda-nr750-with-3-kilometers/ The other with 5km: https://iconicmotorbikeauctions.com/auction/1992-honda-nr750-with-5-kilometers/
The reasons for not buying one are clearly stated in the add for one. If you can't use it then why own it? It's neat but not worth owning unless you are running a museum.
Look around at maisto or one of the scale model makers... they had a few examples you could oogle and handle. I have some promo stuff from an old Honder dealer somewhere in my attic. Funny as the price was as much as my first house at the time. Im positive the house appreciated better...lol
I think they have had a couple on iconic motorbike auctions. I follow them on IG and they get some pretty cool stuff on there.
Not all that hard to find them for sale. I think RC30s, RC45s (who wants one these but) and VF1000s are rarer to find for sale. I would love to get a piston and the con rods from a NR750 though.
Honda asked what if. They answered and moved on. I'd love to have one just for the unique factor. Trying to imagine the piston rings and its just not working in my head.
Question asked: Can Honda be competitive against two strokes with a four stroke if we overcome the limitations of a two valve intake setup? Answer: No, absolutely not. Honda: Sigh ... back to two strokes for GP; our only option.