I'll bite...
B-King : Took 6 years, was first put into production by Lazareth by blatantly stealing Suzuki's concept then copying it with what he had (Busa's and know how). By the time Lazareth had enough back-orders for the next 10 years Suzuki noticed and (finally) went to production

. When they did they took all the toys out of it (head-up display, supercharged motor) and even underpowered it in comparison to what the donor motor (busa) could do. Still a good bike - but one with clipped wings.
Gladius : They must have mis-interpreted the request for a "drag" bike. Also if the Gladius was an SV650 tailored for the masses.....what the hell was the SV650???
V-Max : Way back in the 1980's yamaha thought it would be a cool idea to make a super-fast cruiser bike. They tried it, it worked, became cult icon, then they stopped making it. Late 2000's they rekindle it, add a small amount of spice then say "done". Once again - Lazareth and many others have been reinventing VMAX's for years where Yamaha was asleep. So you would have thought that they would put more effort into the remake. I don't see them re-releasing XS1100's or TZ500's..........yet if they got the old bike and farted their creative talent on it again it would sell like hotcakes.
MT-01 : Great bike and concept. But what they don't tell you was they had a whole range. Look up MT-OS or MT-06 and drool. But turns out people didn't want a big cruiser. On the upside looking at their track-record, you will be able to buy a brand new one in 20 years, which will look just like it does now, when it becomes cool again.
Any other great designs you would like me to prod?
While I am at it here are some of the fallen japanese designs that were original and should have got pushed to production:
Yamaha MT-OS
Suzuki Stratosphere
Yamaha VMN1400r
Yamaha Tessaract
Probably 100's of others I have missed
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