Lying dormant like an Argentine volcano for 75 years, the amazing supercharged Zenith 'Super Kim' has been brought back to roaring life, after a surprisingly short stint on the workbench of Gernot Schuh of Austria. Longtime readers will recall the extensive story of the Sigrand family of Buenos Aires, certainly one of the most interesting in South American motorcycling history (click here for the relevant posts); Roberto Sigrand purchased a racing KTOR J.A.P.-engined 1925 Zenith from England while living temporarily in Europe (studying engineering), and brought the machine home, coming to dominate local speed events in solo and sidecar classes with his 1,000cc racer.
Around 1931, Sigrand began to extensively modify the big Zenith for an attempt at the World Motorcycle Speed Record, adding a large blower, plus all the elegant mechanical support necessary to make it all work. The machine was apparently run up to speed a few times, but remained mostly as a display in the 'Aros Kim' factory which Sigrand owned, as a testament to his engineering prowess.
The story of Why the machine was never truly used in anger will be published later; suffice it to say that it involves much family drama - paternal tensions, political pressures, sex, infidelity, sibling rivalry, even death. It's still a difficult subject for the family, and Ignacio is to be lauded for his efforts at bringing the saga to light, where perhaps the weight and shame of it may be dissolved, as the brilliance of their success is celebrated.
My connection with this machine is described in earlier posts; in sum, I owned and treasured it as perhaps one of the most amazing 'barn finds' ever in motorcycling - to my knowledge, there were simply NO other complete and unrestored supercharged 1920's motorcycles in the world. To have owned it for a time was a gift and a blessing, and a bit of a burden. I knew that any restoration work I commenced would break the magic spell of its sleep, and after a time I reached the conclusion that far deeper pockets than mine would be needed to do the Right Thing - a totally sympathetic restoration to full running condition, without compromising the total originality of the bike.
And I was right. The current owner has commissioned extensive and meticulous work on every aspect of the machine, with the dictum, 'new parts only where the old are missing or destroyed, no new finishes, everything as was wherever possible'. Gernot has fulfilled the task admirably.
He had quite a few surprises along the way! I knew from flashlight inspection that the interior of the combustion chambers were shiny like new, but Gernot's heart must have sagged when he discovered that water had lain in the timing chest and eaten the camshafts.But, going deeper into the motor, almost every part was found to be 'as new' and in pristine condition - the bearings, crankshaft, rods, piston, etc, were all amazingly fresh and needed little to be brought back to life. New camshafts were made - to a grind which indicated their earlier unsupercharged life; too much valve timing overlap for truly successful forced induction, these were very 'hot' racing cams, which must have been used to set all those speed records around 1930. Supercharged engines prefer 'truck' timing, as lots of valve opening overlap tends to blow the induction charge right out the exhaust port! But, the valve timing may have compensated for other faults.
The other great surprise during the rebuild was the engine capacity; 1700cc! The size of a Volkswagen engine - now commonplace on motorcycles, then an absolute Monster. A special crankshaft, rods, cylinders, and pistons were made for the huge displacement (note the special cylinder sleeve cutaways which accomodated the long crank throw).
I had assumed the supercharger, which must be matched in capacity to the engine displacment, had come from an 1100cc MG 'K' car, but it seems the Sigrand family owned a supercharged French sports car of the proper engine size - more on this later.
You can see from the 'finished' photos that the great smoking gun of the Zenith is an impressive machine, and I look forward to a test ride! Stay tuned...
