Rare over­head cam AJS

Old Bike Australasia - - BLOW YOUR OWN -

The first week­end in Novem­ber I at­tended the Jam­pot Rally at Kelso near Bathurst. There was the usual roll up of twin and sin­gle AJS Match­less mo­tor­cy­cles in­clud­ing some nice look­ing Com­pe­ti­tion Mod­els. How­ever one dif­fer­ent ma­chine caught my eye and ap­pealed to me the mo­ment I spot­ted it. It was a 1929 M10SR 500 OHC owned and built by Rob Smyth from South Aus­tralia. He was there with his son Michael who was rid­ing an­other of Rob’s ma­chines, a 1924 B1 350 which Rob pur­chased in 1958 for one pound.

It tran­spires that Rob was an Elec­tri­cal Tech­ni­cian work­ing at the South Aus­tralian In­sti­tute of Tech­nol­ogy which later be­came the Univer­sity of South Aus­tralia. He ex­plained to me that the let­ter M in­di­cates that the ma­chine is a 1929 model, 10 is 500 OHC, S for Spe­cial and R for Rac­ing. His ma­chine was orig­i­nally stamped No.5. When raced it was fit­ted with a side­car and raced by Alex Ridge­way in both scram­bles and short cir­cuit meet­ings. It had a ma­jor en­gine blow up in the late 1940s or early 1950s and never re­built. Chris Har­ley gave Rob some parts and agreed to give more once he saw that he was un­der­tak­ing a re­build­ing task.

Th­ese parts ini­tially con­sisted of two crank­case halves and a cou­ple of heads. The crankcases had been cracked ver­ti­cally and re­quired ex­ten­sive weld­ing. A later model feed oil pump was fit­ted which then re­quired Rob to make a new scav­enge pump which lubri­cates the cam chain. There were no fly­wheels, pis­tons or valves. Steel Red Hunter fly­wheels were fit­ted which gave a 95mm stroke and 83 mm bore. The orig­i­nal en­gine would have been 101 ml stroke with a 79 ml bore. The petrol tank was lo­cated in Bro­ken Hill and the rear 21 inch rim in Mil­dura. The rac­ing ma­chine would have had a four speed gear­box which was un­able to be lo­cated so a 3 speed close ra­tio from an­other 1929 model AJS was fit­ted. Rob tells me that this was the last year that AJS ac­tu­ally made their own gear­box. This ma­chine is fit­ted with a nine inch rear and an eight inch front brake which is cor­rect for the orig­i­nal spec­i­fi­ca­tions. He used a mod­i­fied M8 frame. The orig­i­nal M10SR frame had a third strut go­ing from the back axle to the rear of the en­gine un­der the gear­box. This pro­ject took sev­eral years be­fore it was com­pleted in 2000. He has rid­den this mo­tor­cy­cle in a num­ber of ral­lies dur­ing which time it has clocked up some 27,000 miles. Rob took it to show Alex Ridge­way who then pro­duced a photo of this ma­chine in rac­ing trim. Alex has since passed way. Rob tells me that he is aware that there is also one of th­ese ma­chines be­ing re­stored in Tas­ma­nia.

This ma­chine is a credit to Rob’s en­gi­neer­ing skills and abil­ity and shows how some­body with ded­i­ca­tion can make such a nicely pre­sented and re­li­able mo­tor­cy­cle when they had so very lit­tle to com­mence with.

ABOVE Rob Smyth (right) with the M10SR AJS, and Michael Smyth with a 1924 B1 350 AJS at the 2015 Jam­pot Rally. LEFT The en­gine of the M10SR. A lot of work went into re­build­ing this old racer.

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