80cui:
You raise an interesting question and it made me aware of how far testing instruments have come. I will admit to having no knowledge of what "XRF guns" were until you began this thread. A quick online search enlightened me. XRF = X Ray Fluorescence. The claim is made by makes of these hand-held "XRF Guns" that the composition of a wide variety of materials including metals, composite materials and even wood can be determined in place, with no taking samples to a lab. It sounds like something from science fiction, a bit too good to be true, being able to get an on-the-spot determination of a material's composition.
Assuming the XRF instruments are reasonably accurate, and since they do not require taking a sample of the material (i.e., "non invasive testing"), my opinion is an auction house would be doing their 'due diligence' in using XRF guns. As is well known, forgeries of paintings have made it past the so-called 'experts' and been sold for huge sums of money. Obviously, something like the Cyclone motorcycle in your picture would be a candidate for at least partially 'counterfeiting'. I was always intrigued by the Cyclone engines. For their times, they were very advanced, with design & performance well beyond contemporary motorcycle engines. Their design and performance took a few decades to be equalled by most of the motorcycle engine designs from larger manufacturers.
The Cyclone was designed and built by a firm called "Joerns" in Minneapolis. I do not know the total number of engines Joerns built under the Cyclone design/name. Probably a very small number. As an extremely rare and very advanced design of motorcycle engine for its time, the Cyclone engine would be a likely thing to at least partially 'counterfeit'. I am sure with today's CMM equipment, it would be possible to produce exact working drawings of Cyclone engine parts. Reproducing those parts in this day and age, with CNC machine tools available for things like patternmaking, a set of crankcases or any other cast part could be reproduced.
Now we get to the big question: what if the counterfeit parts were made of the SAME materials or alloys as was used by Joerns way back when ? The crankcases were sand cast aluminum. Assuming someone had a Joerns/Cyclone engine with deteriorated crankcases, and assuming they used those crankcases to 'reverse engineer' new crankcases. If the same sand casting methods and same type/design of cores were used to produce the new crankcases, and the same alloy used to pour them, it could well be the equivalent of a flawless forgery of the Mona Lisa. Roll the clock back to the era when Joerns was building the Cyclone engines. Chances are they sent their patterns to a foundry that poured aluminum. The foundry may well have used loose or approximate methods of making up a 'heat' or 'melt', throwing some aluminum ingots and perhaps some alloying elements that were in common use at the time into the crucible. Even today, if we look at an ASTM (American Society for Testing Materials), or similar specification for various metal alloys, there is often a 'percentage range' for some of the alloying elements. Not exact percentages. If a person in this day and age had an XRF gun analysis of the alloy used to cast the Cyclone crankcases, they could produce a flawless reproduction (assuming they came forward and made it known that this was not an original Cyclone engine). If they followed the same path and acted like they had a working Cyclone engine/motorcycle, then they'd be offering a counterfeit (or partially counterfeit) motorcycle for sale.
I am sure XRF is well-settled and proven technology. If I were in a position to bid on a Cyclone motorcycle at auction, I would be questioning what the fancy auction houses call "the provenance". I.E., the history of the motorcycle in terms of who owned it, what modifications or rebuilds were done to it, and any other information about it. Aside from the "provenance", I'd be wondering how a Cyclone engine survived in good to excellent condition. The Cyclone motorcycles were made to be raced and pushed hard. As I recall, while they had the impressive performance figures for those engines, the engines often did not last thru a race. Given that history and the rarity of a Cyclone motorcycle, I'd be asking for all the proof I could get as to the authenticity of the motorcycle and its engine. It is akin to someone laying claim to an estate, and using DNA to determine if the claimant was legitimate or an imposter.
I've been intrigued with the Cyclone engines for years, wondering who Joerns was ( a machine shop in Minneapolis is about all I know of them). Who designed that engine and why didn't the motorcycle industry pick up on the design and use it sooner ? I suppose the answer is that side valve (aka "flathead") engines worked well enough for motorcycles sold to the public, and were a lot easier and cheaper to build.
