This Rudge story was unearthed by Marc Farmer who thought it might be of interest - rightly so !
V.M.C.C. stalwart Trevor Hopkins tells the story so far of a 1925 gem, a tale that gets to the heart of the old-bike racing psyche.
I am always on the lookout for interesting machinery, and browsing through the Rudge Rally autojumble 1 found a very neglected engine complete with ML (later Lucas) magneto, lying on a blanket. A check of engine numbers in the V.M.C.C.'s bible of everything in the universe revealed the motor to be a 1925, 350cc four-valve Rudge of otherwise unknown origin.
I quickly sought the wisdom of everyone I knew. Stuart Towner: "Them's fragile." Club founder Titch Alien: "I can't think why you're bothering. They were never any good even when they were new." But more delving for historical evidence gave me the inspiration to continue.
This was the first real four-valve, four-speed, all chain drive motorcycle to be available to the working man and sportsman. No doubt many were raced and some did appear at the dawn of dirt-track racing in 1929, when it was ride to the meeting, strip off lights and other extraneous items, race, put it all back on again and all being well ride home.
On stripping the engine I found out just how fragile the little beast was. Flimsy flywheels, single main bearings, big end no bigger than the other end. It had beautiful little tulip valves, a strange piston and no oil pump.
The oiling system was primitive: one - pump lubricant on to the single lobe cam in the timing case, let it drip through a hole into the crankcase where it would flick about to give some relief to the bearings, rod and piston; two - allow it to drop out of a hole on to the primary chain and the road. Some radical thinking was required.
The head was not too difficult. First, take Vauxhall Viva valves, cut to length, mate to Mini valve springers (outers only to reduce the struggle the single-lobe cam had to put up), Mini valve caps and collets, proprietary bronze guides cut and Shaped.
The head was gas flowed to perfection and an Amal dirt- track twin-float carb of the correct vintage fitted. It burns alcohol.
The scored barrel was rebored and a 1930 Lumpy-topped BSA piston fitted; also exposed pushrods fabricated from BMC 1 100 originals; and ball end adjusters from the same engine incorporated into the rocker gear. Heeding the warnings of "them that know," about barrels snapping off at the base I Fitted tie-bolts to clamp head and barrel to the crank-case.
About now I heard of a Royal Enfield dirt-tracker less engine, which I obtained (from Bryan Lambert), and soon afterwards a Rudge four- speed gearbox and clutch. Towner suggested the bike should be called the Royal Rudge. The bottom end problem still remained and it seemed obvious to begin the search for beefier flywheels with later Rudge machines. I found these would fit but crankpins and rods were like hens' teeth. However, I Found some rusty flywheels, a very secondhand crankpin and con-rod pitted through hardening.
This was where Derek Hoult of INA came into his own. 'Best fit' decisions were made via a catalogue. The flywheels were machined and lightened, the crankpin ground, rod bored top and bottom, bronze little end and finally a needle roller bearing Fitted. Needless to say the clearances are all just so, an excellent job. It happens that later Rudge engines had an end-fed crankpin to deliver the precious Castrol R. I found one of these could be made to Fit, along with a better oil pump - a relief as with higher compression and a methanol diet the loads would be Far greater than standard.
A so-called friend asked: "What about the cam?" I therefore again went for a later Rudge component, grinding off the inlet lobe and allowing the lumpy exhaust profile to improve performance. It's amazing, but profiled cam followers of different lengths control valve timing very well.
We are now up and running. There is still development work to do but considering the engine's age it goes really well already. My sincere thanks to all who have helped. We should all Feel pleased that we have saved a pioneering engineering concept from deteriorating further. But the Royal Rudge's finest hour will be when she blasts to racing glory!
Having read this article, Bryan Lambert, himself an active VMCC member, mailed me the following information.
Ronnie and his father built a small batch of machines in the early 70s to challenge the 250cc Rudges which then dominated the class ( no C15s then ) using 250cc dog-ear JAPs . Another , in Excelsior cycle parts , survives in the hands of Manuel Hughes who rates it as very quick but too fragile to use . I sold the engine to Reg Kelly the SOS expert who wanted it for the 1930 TT entry SOS he was restoring and fitted a 350cc 5-stud JAP .
Unfortunately the 350 motor was too much for the cycle parts ( particularly the transmission ) so I sold them to Trevor and fitted the motor into BSA cycle parts ( from a 250cc sidevalve ) which have been a lot better although the handling leaves quite a lot to be desired , like the right steering head angle for one thing . When I got the bike it carried the number 27 which was adopted by Ronnie as a gesture to Dick Tolley ( Enfield -JAP you see ) and I still carry that number for VMCC grasstrack - although work commitments have prevented me from riding more than once or twice this year
You're right about the Vintage 350cc class , that's real "mad professor" country . Other machines competing in that class include two "flat-tank" AJS , one with the longest hand-and-foot gear-change linkage I've ever seen , a Levis 4-stroke , my BSA Blue Star , and the Clarke families' Rudges which can make "fastest of the day" against all comers when conditions are right . April's hillclimb produced a Chater Lea which last competed in the 70s having been used regularly since the beginnings of the Club after the second world war . These are real competitors though , if you think they're not racing get out there and try it ! ......