An update on the Velo Viceroy which was featured in RC158/159. From the get-go, the left cylinder was doing most of the work. Quick checks showed no abnormality so it was time to investigate. Out came the engine, a 30 minute job. Off with its heads and barrels and out with the crank. Owing to the bike’s lifetime of storage before its rebuild, the pistons had rusted in the barrels. The person who had done the drive-by paint job mentioned in my first instalment had also inflicted GBH to the engine in his ‘get it running and flog it’ actions.
The barrels had been rebored after the old pistons had been hammered out. The problem was that left side was 4 thou over what it should be, and the other side was a whopping 8 thou over! This resulted in the new plus-20 pistons rattling about in the bores. The right side was so loose that I assumed this was the cause of the right cylinder being a laggard… but wait, there is more.
The crank seals had been changed but the ones fitted were metric with the outside diameter 4 thou oversize. Matey boy had simply applied a heavier hammer and stuffed them in anyway, mangling the seals in the process. I was convinced that Velocette in 1961 were still firmly ensconced in Imperial measurements. I applied my measuring stick to the job to find, as expected, it was all in the Queen’s own perches, bushels and pecks. The correct seals were available off the shelf from my local bearing shop so in they went.
To correct the cock-up with the barrel boring I had to rebore again, 10 thou over the existing nominal plus-20. Modified Enfield Flying Flea pistons were on hand, so rebuilding commenced. The replacement pistons and the original Velo pistons had no arrow on the top to signify direction of fitting. My non was plussed with this situation, so I gawped over a cuppa tea at the transfer port windows in the bores compared to the pistons. EUREKA! the windows in the pistons were situated off the centre line of the pin, and the windows in the barrels were likewise off centre. This funderment dictated that the pistons had to be fitted so that the windows in the barrels were in harmony with the pistons.
Having marked the old pistons upon removal, it was easy to see that the left piston had been correctly installed but the bone idle right-side piston was half a turn out. This had the result that a considerable area of the transfer ports was blocked off.
The Velo workshop manual indicates that the York Road boys had no truck with rebores. ‘In the event of wear of the cylinders they are to be returned to the factory to have the steel liner replaced.’ Now we know!
The lovely little Viceroy now hums along beautifully as it should, with still only a handful of miles on it since it left Hall Green.
Roger Slater, member 2429
That is one seriously excellent machine, Roger. A shame that you’ve declined my generous $100 offer for it! Frank W
1: The transfer window is offset from the centre line
2: Reed valve assembly goes on top of crankcase, downstream from the carb. The upper blades are the opening stops, the SS blades are below
3: Crank very nicely machined all over, note the milled slots for oil ways to the needle rollers
4. Top of the crankcase halves. Barrels are offset and deeply spigoted into the cases