Page 5 - Sound Rides Feb 2023

The Burt Munro Story
Herbert ('Burt') James Munro was born on the 25th of March 1899 at Edendale, a country
town 30km from Invercargill, New Zealand.
Burt bought his Indian motorbike new in 1920 as a standard model Indian Scout which had a side
valve engine of 600cc capacity. The price was ₤120 with acetylene lighting although he could have
bought an electric lighting model, but it was quite a bit more expensive at the time. The engine
number was 50R627.
The Indian Scout was very advanced for its time with a helical gear transmission and a mechanical oil
pump working on a total loss system. The top speed was in the region of 60mph.
Early in the 1920′s Burt started tuning his bike for speed and eventually had it exceeding 90mph in
side-valve form. In the mid 1930's Burt made patterns for an overhead valve engine conversion but
initially he was quite disappointed to find it was no faster than the original side valve. However, with
determination Burt persisted with the tuning and in 1940 he gained the New Zealand Motorcycle speed
record reaching a speed of 120.8mph. At this stage Burt found the original con-rods would not stand
up to the strain so he started making his own using old Ford truck axles. Burt had very little specialist
equipment, so a lot of his machining work was done by hand. After overcoming the earlier con-rod
failures, Burt experienced engine big-end failure. As the lubrication was achieved by a total loss
system, which had no direct feed to the big-ends and crank pin, the rollers often came out blued and
fused to the big-end cage. Eventually Burt made new fly wheels and increased the diameter of the
crank pin which was bored to feed oil direct to the big-ends. He also fitted an Indian Chief oil pump
and in doing so changed the lubrication to a dry sump system. Over the next few years Burt gradually
increased the bore and stroke which enlarged the engine to just on 1000cc capacity. Burt cast his own
pistons using a large kerosene blow lamp and casting dies he made himself. Another modification he
made was to the primary transmission. Burt made sprockets for this and fitted a triplex chain on the
primary drive, in place of helical gears as this was more efficient. The clutch is basically standard with
extra springs fitted to cope with the extra power the engine was developing. In order to get closer
ratios in the gear box Burt cut the layshaft and welded two pinions from an Indian Chief onto his Scout
layshaft in order to get closer ratios on the three-speed gear box. Originally, Indian Scouts had only
two cams which limited the valve timing, so Burt changed this to a four-cam system, allowing him to
alter the valve timing on both the inlet and exhaust valves. Over the years, Burt also built four
different "Streamliner" shells for the Indian Scout, based on the aerodynamic shape of a goldfish. On
his first trip taking the Indian Scout to the Bonneville salt Flats in Utah, USA on 20th August 1962,
Burt achieved a speed of 179mph, something people attending the famous “Speed Week” found
absolutely unbelievable considering the age of both the bike and the rider.
On the 26th August 1967 Burt claimed the World Record Class S-A 1000cc – with an average speed of
184.087mph. - North run (184.710mph) and South run (183.463mph). As the Class has since been
retired, this record still stands today. Another of Burt's bikes which should have received a lot more
publicity than it did was his 1936 MSS 500cc Velocette. It was lightened and lowered in true Munro
style to be under 200 pounds in weight.
Burt increased the capacity to 650cc, and it was timed at 138mph which would make it one of the
fastest Velocette's in the world at the time; if not the fastest. Had Burt’s health not failed when he was
75 years of age, he intended also taking the motor and gear box of this bike to America and fitting it
to the streamlined shell. There is a strong possibility it could have exceeded 160mph providing he had
two good runs. After suffering a partial stroke in 1977 Burt found he had a lack of co-ordination and
concentration when trying to work on the machines, leaving him very frustrated. He sold us his 1920
Indian Scout - the "Munro Special", his 1936 Velocette 500 plus various engine parts and motorcycle
trailer so that they could remain in his beloved Southland.
Herbert (Burt) James Munro died on 6th January 1978 - aged 78 - of natural causes.
There is no doubt at all that this was the most successful combination of man and machine during 57
years of passionate development. To increase the performance of such a motorcycle as his from
60mph to almost 200mph was the most remarkable achievement that motorcycling had ever seen.
Neville Hayes (E Hayes and Sons hardware store in Invercargill).

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