{"id":28186,"date":"2024-11-24T00:01:03","date_gmt":"2024-11-24T08:01:03","guid":{"rendered":"https:\/\/exhaustnotes.us\/blog\/?p=28186"},"modified":"2024-11-24T06:20:48","modified_gmt":"2024-11-24T14:20:48","slug":"potato-potato-potato","status":"publish","type":"post","link":"https:\/\/exhaustnotes.us\/blog\/index.php\/2024\/11\/24\/potato-potato-potato\/","title":{"rendered":"Potato Potato Potato"},"content":{"rendered":"
By Joe Berk<\/h6>\n

Love them or hate them, there’s something about Harley-Davidson motorcycles that command attention, and during our recent visit to the Harley museum in Milwaukee, one of the exhibits that grabbed my attention was The Engine Wall.\u00a0 It had a magnificent display of Harley-Davidson engines including their big twins, their small twins, and other engines in the Harley family tree.\u00a0 I always found the evolution of the big twin engines mildly confusing, but this dramatic display cleared all that up.\u00a0 I grabbed a photo of each one and I thought I’d share them with you here on the blog.<\/p>\n

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F-Head (1911-1929)<\/strong><\/p>\n

The F-head engines were 61 cubic inches, and later, 74 cubic inches.\u00a0 These were Harley’s first v-twin engines, and they featured an inlet over exhaust valve configuration.\u00a0 \u00a0What that means is that the intake valve was an overhead valve contained in the cylinder head (it moved down to let in the air-fuel mixture), and the exhaust valve was a side valve (or flathead valve) contained in the cylinder on one side (it moved up to allow the exhaust gases to escape).\u00a0 \u00a0Inlet over exhaust internal combustion engine configurations (or F-heads) were fairly common in the early days of gasoline engines.\u00a0 If you draw the arrangement schematically, it sort of looks like an F (hence the name).\u00a0 The larger of the two Harley F-head models produced 11 horsepower.<\/p>\n

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The F-Head configuration.<\/figcaption><\/figure>\n
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V-Series Flathead (1930-1936)<\/strong><\/p>\n

The V-series flatheads were either 45 cubic inches or 74 cubic inches.\u00a0 They were sidevalve engines, which means the valves and their seats faced up and were located in the cylinders (not the cylinder heads), alongside piston (hence the sidevalve descriptor).\u00a0 This allowed the head to be basically flat (when viewed from the bottom), and that’s why these engines are called flatheads.\u00a0 It’s an old school design and it works well, but due to the twists and turns the intake and exhaust gases have to make and their poor heat dissipation, flatheads are limited in how much power they can produce.\u00a0 Harley would get around to fixing that in 1936 with the introduction of their overhead valve Knucklehead engine, but that would be down the road.\u00a0 \u00a0Read on; we’ll get to that.<\/p>\n

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U-Series Flathead (1937-1948)<\/strong><\/p>\n

This was the second iteration of Harley’s sidevalve (or flathead) engines.\u00a0 There were two versions:\u00a0 The U and UL models (both had 74 cubic inches), and the UH and ULH (these had 80 cubic inches).\u00a0 The U series of engines were used for both motorcycles and Harley’s three-wheeled vehicles.<\/p>\n

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Knucklehead (1936-1947)<\/strong><\/p>\n

The Knucklehead was the first of Harley’s overhead valve engines, and the knucklehead name was derived from the valve covers’ appearance.\u00a0 Knuckleheads were made in a 61 cubic inch model and then in 1941, a 74 cubic inch configuration.<\/p>\n

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I’ve read that Knucklehead engines had serious oil leak issues caused by an overly complex rocker box cover (something Harley tried to correct with the next engine configuration, the Panhead).\u00a0 Knuckleheads had cast iron cylinder heads, which tended to make them run hot (cast iron does not dissipate heat very well). The Knucklehead motorcycles were the first Harleys that featured their distinctive Big Twin style, something that Harley has kept right up to present-day offerings.<\/p>\n

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Panhead (1948-1965)<\/strong><\/p>\n

The Panhead Harleys got their name from the valve covers’ appearance (they look like pans).\u00a0 This engine and the Evo engine (the engine that appeared two iterations later) are, in my opinion, the two best looking engines Harley ever made.\u00a0 In a major design shift for Harley, Panhead cylinder heads were made of aluminum, which improved heat dissipation and temperature control.\u00a0 The Panhead was intended to improve performance and address the oil leak issues associated with the Knucklehead.\u00a0 Did it work?\u00a0 I don’t know.\u00a0 I’ve never seen a Panhead Harley that did not leak.\u00a0 They sure are beautiful, though. The Panhead had a short production run, but it had a major impact on Harley styling.<\/p>\n

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The last year of the Panhead (1965) was the first year Harley had electric starting (that was when Harley introduced the Electra Glide name).\u00a0 My two ultimate dream bikes are the 1965 Harley Electra Glide and the Norton P-11 (which is discussed elsewhere on ExNotes).\u00a0 In my opinion, Panhead Harleys are exceptionally beautiful motorcycles.<\/p>\n

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Shovelhead (1966-1984)<\/strong><\/p>\n

1966 saw the introduction of another Harley engine, and yet another name based on the rocker box appearance.<\/p>\n

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I had a Shovelhead (a 1979 Electra Glide Classic).\u00a0 It was so bad I called it the Optical Illusion (because it looked like a motorcycle).\u00a0 My shovelhead Electra Glide was the worst motor vehicle of any type I ever owned (car, motorcycle, lawn mower, and Cox-.049-model airplane). It was constantly plagued by oil leaks and breakdown.\u00a0 It wouldn’t go a hundred miles without something breaking.\u00a0 After coming off a Triumph Bonneville, the Harley handled like a garbage truck.\u00a0 It would hang an exhaust valve every 4,000 miles, and as it was explained to me by the dealer, it was because when unleaded gasoline was introduced in the US, the valves would stick in the valve guides without the added lubricity provided by leaded gas.\u00a0 I don’t know if that was the reason or not, but in 12,000 miles, that bike needed three valve jobs (the first two were on the dealer with the bike’s 12,000-mile warranty; the third was on me because the bike had just over 12,000 miles.\u00a0 \u00a0After paying for that last valve job, I sold my Electra Glide and I swore I’d never buy another Harley (but I did; see below).\u00a0 It was beautiful, though, and I wish I had kept it.<\/p>\n

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Evolution (1984-1999)<\/strong><\/p>\n

Harley got their act together on this one, and it was probably because they subcontracted the engineering to Porsche.\u00a0 Willie G drove a Porsche, and he knew they knew how to engineer engines.\u00a0 It was a good move.\u00a0 I had a ’92 Heritage Softail and it was a great motorcycle. My dealer?\u00a0 Not so much, but I guess it was all part of the Harley experience.\u00a0 I put a lot of fun miles on my ’92 including trips all over the US Southwest and Mexico, and I enjoyed riding it.\u00a0 The engine style was great, too.<\/p>\n

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In my opinion, the Evo engine was one of the two best-looking motors Harley ever made (the other was the Panhead; see above).<\/p>\n

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Twin Cam (1999-2017)<\/strong><\/p>\n

The thing most amazing to me about the Twin Cam engine was that Harley kept it as long as they did.\u00a0 It was basically a bust.\u00a0 Plagued by mechanical failures and overheating from the get-go, one had to be either ignorant or a masochist to buy a Harley with a Twin Cam motor.\u00a0 Cam failures, lubrication failures, and overheating were a fact of life if you owned one of these.\u00a0 \u00a0The rear cylinder overheating issue was so bad that Harley incorporated a switch and an automated feature to shut down the rear cylinder if the engine got too hot.\u00a0 \u00a0Amazingly and amusingly (at least to anyone with any mechanical smarts), Harley called activation of the rear cylinder shutdown feature their “parade mode,” with the implication that it was intended to accommodate riders who rode in, you know, parades. There were kits available to shield the riders’ legs from the intense heat the rear cylinder generated.<\/p>\n

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Twin Cam Rushmore (2014-2016)<\/strong><\/p>\n

This is a higher performance version of the Twin Cam engine that involved many changes, the most significant of which was liquid cooling for the cylinder heads on the Ultra Limited, CVO Limited, and Tri-Glide models (the models in which the radiators could be hidden; you can’t have a Big Twin Harley looking like a Gold Wing, I guess).<\/p>\n

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Milwaukee Eight (2017 to Present)<\/strong><\/p>\n

Harley joined much of the rest of the world in 2017 when they incorporated four valves (two intake, two exhaust) for each cylinder.\u00a0 Let’s see…two cylinders, four valves per cylinder…that makes eight, and Harley’s hometown is Milwaukee.\u00a0 Hey, the Milwaukee Eight!\u00a0 (At least the name makes more sense than the Rushmore mentioned above.)\u00a0 \u00a0These engines had problems and Harley had recalls to address them.\u00a0 Wet sumping was a major issue, as was overheating.\u00a0 \u00a0The Milwaukee Eight incorporated a plastic intake manifold, too, which also had issues.\u00a0 I like the name, though.<\/p>\n

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I thought the Harley Museum’s Engine Wall was very, very well done.\u00a0\u00a0Harley put a lot of thought and work into it, and as a mechanical engineer and former Harley owner, I enjoyed it.\u00a0 There’s the obvious:\u00a0 the actual engines on display.\u00a0 And then there’s the subtle:\u00a0 the slight tilt of that orange wall toward the visitors so that the engines were presented not an angle, but straight on as you tilt your head up to view the different engines.\u00a0 The colors are classic Harley:\u00a0 black, orange, and chrome.\u00a0 It’s one of the better displays I’ve seen of any type in any museum.\u00a0 The whole thing just works.\u00a0 Harley got The Engine Wall right; they did an awesome job.<\/p>\n

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As mentioned at the start of this blog, there were more engines on The Engine Wall.\u00a0 These included their smaller engines (for the Sportsters and the racebikes), their singles, and some interesting other twins.\u00a0 Keep an eye on ExNotes; we’ll show those, too.<\/p>\n

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Never miss an ExNotes blog:<\/p>\n

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