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As much as we enjoy ventral, thoractic endowment, this is not a site about nice bosoms. Sorry.
Major re-write currently in progress - watch modified datetime at page bottom. There is considerable over-spill between this domain (http://bigtwins.org/Main/)
and the eCommerce site https://bigtwins.co/ This site is supposed to be informational
and the other is meant for trade. Sadly, I wax on over products here and over there I
conjecture on potential products. I'll try to keep them as separate as I can.
Up through the seventies, we saw the development of the UJM (Universal Japanese Motorcycle).
It sported (ususally) four transverse cylinders; was moderately to rather sporting and just not that innovative (yet).
The Big Four cast their avaricious eyes on the world market and saw a a segment that was occupied by
big (and huge) V Twins. It was time to make a foray. In 1981 Yamaha was first - with a 981cc chain-drive sports-bike - the TR1..
In the Americas, they launched a 749cc shaft-drive cruiser (the Virago) and a slightly smaller 920cc version of the TR1; without that designation.
They were about a third the cost of other V Twins (excepting the Moto Morini and other small models)
and Yamaha cranked them out as fast as could be done. There were many glitches and a lot of warranty recalls on the first few batches.
Steps were skipped even on those that passed QA. Fr a few years, no other mfg followed the V Twins lead (there were a few V fours)
and Yamaha had a virtual monopoly on them.
The following model year saw the addition of a 920 version of the Virago with a shaft drive.
The chaindrive's days were numbered as it MSRP'd at $3695 while Yamaha had a much quicker 900 four that sold for $3295.
In '83, there was a Virago 750 and a 920; the chain-drive was gone, but left-over unsold models were available as late as 1987;
when one could get one out-the-door for about a thousand dollars.
Between 1981 and 1998, Yamaha made millions of V Twin motors for their Virago line of bikes, with displacements of from 699cc to 1063cc.
The designation was also applied to some unrelated entry-level minis of from 50cc to 535cc.
The basic design of the larger bikes continued from 1999 through 2009 in the XVS1100 V Star model.
That's quite a run. Engine parts and some peripherals interchange.
For the record, Yamaha did everyone dirty by their naming schemes. The chain-drive model was emphatically NOT a Virago,
although Yamaha began calling it one -- long after its production ceased. Also, the designations XV and Virago should not have been assigned to the
bikes which were so-called that displaced less than 699cc. Other than having some stylistic similarities, they are clearly not of the same family.
Similarly with the V Star series, while most are designated XVS, some carry the XV designation,
although they are not related to the earlier models. The XVS1100 was, however, a Virago descendent, yet did not get the XV prefix.
After the demise of the chain-drive model, the shaft-driven flagship grew to 981cc, then to 1063cc. Now sporting a bore and stroke of 95mmx75mm,
they made no more power (perhaps less, even), but were quicker "out of the hole." Sales were modest, but enough to keep production going to 1998.
The next year, the Virago 1100 became the V-Star 1100. It sported plated bores and deeper finning, and a cam so mild that Yamaha did away with the
inner valve spring. It also side-stepped the pervasive starter problems by going to a roller clutch arrangement. Even that was not enough,
as Yamaha superseded the entire starter mechanism with an after-the-fact update kit. This was well after production of this model had ceased.
For the record, the adult-sized XV series bikes (and the XVS1100 V Star) were two valve, single overhead cam, seventy five degree v twins with side-by-side
rods on plain bearings. They breathed through a pair of 40mm constant velocity carbs: Hitachi until about '92, then Mikuni; The V Star through 37mm.
The alternator, starter gears, and oil pump were behind the left engine cover; the clutch behind the right. The drive gears and clutch basket were
the same parts throughout the series. The early bikes (Gen I) used the engine as a stressed member; later bikes a cradle frame.
The 700 and seven fifty sported 43mm intake valves, 37mm exhausts. All the rest were 47mm and 39mm, respectively. the valve springs were all the same:
except the XVS only ran the outer. The guides, seals, retainers, and keepers were all the same. Interestingly, the intake valve, springs, and seals
were the same as the SR/TT/XT500 series singles. The exhaust valve was a close enough miss that it would fit.
The retainers, guides, and keepers were different.