Issue link: https://read.dmtmag.com/i/763593
69 www.thunderpress.net THUNDER PRESS nJanuary 2017n So here's your basic 1916 Model 17. Note the engine mounting plates, manual oil pump, the four short head pipes, the confi guration of the cam cover, the pushrods and brackets for the rocker arms? This is the racer Harley only used for team riders before World War I. Except for the front forks! (In our last installment, you might have noticed that both the Harley ad and the over-restored 1916 bike pictured feature "girder" forks… not the springer.) Just consider this our fi rst example of modifi cations to these race bikes. This 1918 model, if accurately dated, has already been subject to a wad of detailed differ- ences and more than a few major ones. Differences that are easy to spot include the lack of head pipes and the oval-shaped exhaust ports, cam cover confi guration, the pushrod bracket redesign, and the fascinating contraption wrapped around the bottom of the front cylinder… which connects to what appears to be an external automatic pump on the cam cover that, in turn, has a fat tube running down to it from the top of the engine. (Fact is, you could specify a manual pump, automatic pump… or both!) The cam lifter (compres- sion release to us) in front is still there, but operated by rod linkages, not a cable. The list goes on, but as you observe, you begin to realize there just might be more differences than similarities in each and every one of these engines. Not to mentions chassis! Sort of a tai- lor-made no-two-alike deal. Of course it could also be after all these years, that the heads on this one aren't the same ones it left the factory with, couldn't it? While you're pondering that notion, what about this? What we have here is a 1927 eight- valve (recently unearthed in New Zealand, attached to a sidecar) which sold at auction for an astounding $600,000-plus! As dirty as it appears, this one is pretty much the "clean- est" so far and is likely to be representative of the last of them. Look once more at the tap- pet deck on the twin cam case. Is it me, or are the pushrod bottoms perched side by side, rather than staggered as with the other examples? They run nearly parallel to the rocker arms as well. Those heads are most likely the fi nal iteration (big-valve, oval-ported) just to sweeten the deal. And how about that left side-facing carb… eh? Although you can't see it in these pictures, the spark plug location in eight-valve heads "migrated" higher and higher in each redesign, until they arrived at the "modern" location above and between the valves. For a sharp contrast (as pictured in part one of this treatise), look at plug location in the Indian 8-V racers! These kinds of subtle variations and refi nements in the Model 17 are all the more reason they had such a horsepower advantage. This one is a 1923 model… although another eight-valve mystery might be, "How the hell would you know for sure?" Is all this dating business based on when it was built, when it was sold, when it was raced… or what? Harley did ultimately sell some — supposedly only to "qualifi ed" buyers in overseas markets — after they quit using them in the U.S. But did they build a bunch of bottom ends and add the current version of the heads at the point of sale… perhaps years later? Or maybe build the whole thing with what was on hand once ordered… a little of both… or what? What's more certain is this particular eight-valve has what should be correct-version heads for the year, and an equally correct version of racing carburetor. But hold on! What's the deal with the pushrods? A close look at the "tappet block" area sure seems to reveal a total reversal of intake and exhaust cam lobes inside the case… doesn't it? Jeez! Could that mean one of these twin cam bottom ends is indirect-acting and the other direct-acting? See "Motorhead," page 73, column1 "By the summer of 1919 the eight-valve racers were back to continue their winning ways. But they weren't exactly the three-year-old stuff. No, sir! No 1916 race bikes and no moth balls in H-D's arsenal… these things were new and different."