Yamaha OW60 square four

The only surviving example outside the factory of Yamaha’s ultra-rare rotary-valve square-four.
This 500cc OW60 is the GP racer that was owned by French Yamaha importer Sonauto and on which Marc Fontan placed tenth in the 1982 World Championship standings.
Despite Yamaha being massively outnumbered by strong Suzuki opposition, he finished in the top ten in eight GP races and also rewarded Sonauto with the French National Championship. Only eight examples of the Yamaha OW60 were ever built and they were to all intents and purposes an outright copy of the rival Suzuki RG500 which, with its rotary valve induction, had outclassed Roberts’ 1980 World Championship-winning piston-port OW48R for speed.
Kenny only rode the OW60 square four in one Grand Prix, using it to win the opening round of the 1982 season in Argentina. After that he concentrated on developing the OW61 vee-four – not an easy task as it turned out, as he never won another GP that year.
The Yamaha OW60 square-four did, however, have its moments in the sun. In 1982, Crosby won the prestigious Imola 200 and was runner-up in the World Championship. Then in both 1983 and 1984, Kenny Roberts won the equally-important Daytona 200 (in 1983 and 184) on the OW69, a bored and stroked 695cc version of the OW60 that produced 175bhp!
In fact, all things considered, the Yamaha OW square four was a bike that could have been a World Champion but which was never given a fair chance in the hands of the top rider of the day.
For more pics see
Yamaha OW60

RG, RD, RGV and YZR500 specials

One of the best places to find pics and get inspiration on two stroke 500 specials and 500 GP replica's is this topic on the Daidegas forum.
Le 500 2T speciale e replica

RG500 and RG400 production numbers

Model Location Qty Yr MFG Dates
RG500G exported 7340 86 4/85 - 3/86
RG500G exported 606 87 4/86 - 3/87
RG500CH exported 806 87 4/86 - 3/87
RG500G Japan 22 88 4/87 - 3/88
RG500CH exported 510 88 4/87 - 3/88
Total 9284

RG400 Japan 5002 86 4/85 - 3/86
RG400 Japan 2-UK 863 87 4/86 - 3/87
RG400H Japan 348 88 4/87 - 3/88
Total 6213

RG500G UK 902
RG500CH UK 240
RG400 UK 2
Total 1144

Frame numbers
RG500EWC - HM31A-100001~
RG500EW-W (Walter Wolf type 1) - HM31A-102691~
RG500EW-2W (Walter Wolf type 2) - HM31A-105061~
RG500CH - HM31A-105405~
RG500G (E34) - HM31B-100001~
RG500CH (E34) - HM31B-101646~
RG400EW - HK31A-100001~
RG400EW-2/2C - HK31A-106287~

Here is the information on RG500's sold in Canada:
870 RG500G's were sold by Suzuki Canada
The first VIN was 0G2100012, the last was 9G2100882
There were 99 Walter Wolf models imported and sold
The first VIN was 0G2100883 and the last one was 2G2100982

Here are the country/model codes:
00 Japan ("Home" or "domestic" market)
02 United Kingdom
03 United States
04 France
17 Zweden
18 Switzerland
21 Belgium
22 Germany
24 Australia and New Zealand
25 The Netherlands
28 Canada
33 California

34 Italy

37 Brazil

39 Austria

53 Spain

For a complete list of Suzuki country codes see

Suzuki Motorcycle Country Codes Identification

VIN codes on all motor vehicles sold in North America may be deciphered as follows using this RG500 VIN code as an example: JS1HM31A2G2100951: 
JS1HM31A2G2100951 = JS1 HM31A 2 G 2 100951

JS1 : Japan Suzuki

HM31A: vehicle type

2: check digit

G: model year F=85,G=86,H=87,J=88 

2: plant code

100951: ID number

Earlier numbers, like 001 through 005 or so are usually destroyed, as they are "Production Prototypes"

Fior Suzuki RG500

Thought I knew all the RG500 racers until I stumbled upon some pics of a very special one made by Claude Fior. It has the Hossack front fork, a trade mark of many Fior bikes.
For more pics see 
Fior RG500

Red Bull Yamaha YZR500

King of slide, Gary McCoy on the Yamaha YZR500.
For more pics see 
Red Bull Yamaha YZR500

Central Classics Houten 2017

Kreidler 50cc racing engine, seen at the Central Classics a large motorcycle jumble in Houten the Netherlands.
For more pics see
Central Classics Houten 2017

Ex Paul Hanson Barton Phoenix sidecar

Ex Paul Hanson 1980 Barton Phoenix 750cc Racing Sidecar Outfit

'During 1996 the Phoenix number 2 engine reappeared in the hands of Manchester sidecar racer Paul Hanson. Housed in a Derbyshire kneeler chassis the Phoenix was raced at a Forgotten Era meeting at Barkston Heath, after initially being outlawed on the grounds that it was too fast.' – Mick Walker & Rob Carrick, 'British Performance Two-strokes'.

This racing sidecar outfit was built in 1980 by its sole owner, Paul Hanson, utilising a new Barton Phoenix 750cc engine and a Derbyshire chassis. The Phoenix engines were produced in very small numbers, estimates varying between five and eight examples of the 750cc motor manufactured. Barton had been founded by engineers Barry Hart and Tony Ryan, and made its first impact on the racing scene with a three-cylinder water-cooled '500' based on the Suzuki GT380 bottom end. Ridden by Martin Sharpe, a Spondon-framed, Barton-engined 'Sparton' won the 1976 North West 200 with similarly-mounted Frank Kennedy in 2nd place, while the previous year Sharpe's bike had proved as fast as the works Kawasakis at the Isle of Man TT. The switch to a square-four engine came about after Barry Sheene asked Hart to convert an RG500 engine to 650cc, something the factory said could not be done. Hart nevertheless succeeded and used the knowledge gained to produce his own version of the Suzuki engine: the Barton Phoenix, initially as a '750' and later as a '500'. The Phoenix engine showed promise but the project never received the financial backing required to develop it, despite Hart's appeals to the patriotism of the motorcycling public and a deal with the Rank Organisation to provide machines for the 1978 film 'Silver Dream Racer' starring David Essex. Although it achieved little in solo form, the 750cc Phoenix engine enjoyed considerable success as a sidecar power unit in the hands of Nigel Rollason, whose first major success with it was a 2nd place finish in the 1979 Isle of Man TT. Rollason would go on to finish nine out of ten TTs with his Phoenix-powered outfit, eight of them on the leader board, the highlight being victory in the 1986 event. By then Barton Engineering had ceased to exist, having been purchased by Armstrong in 1981. Barry Hart moved to Armstrong as chief designer and would be responsible for its highly successful Rotax-based tandem-twin racers.

A well-known and respected sidecar competitor, Paul Hanson spent some time refining his outfit's engine and chassis, incorporating various developments such as Armstrong cylinders and an improved fuel supply system, a process that culminated in him winning the 1985 Formula 5 Championship with passenger Stuart Aspin. The outfit continued to be raced regularly until the late 1990s. Thereafter it was used only for occasional parades, the last outing being at the 'Festival of 1000 Bikes' at Mallory Park in 2010.
For more pics see
Hanson Barton Phoenix