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FortNine explains why the 270 degree engine design is so popular
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Wed Jan 31, 2024 11:15 pm (Last edited: Thu Feb 01, 2024 12:00 am)
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This is an interesting discussion regarding why the trend to make 270 degree crankshaft engines are so popular with manufacturers now and not in the past: Current motorcycle collection: 2002 Yamaha FZ1; 2020 KTM 390 Duke; 2009 BMW F650GS; 2018 Zero S 16.6 kWh |
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I like Ryan but he is banging on about cross plane engines of the last decade as the resurgence of 270 degree cranks, but seems to be oblivious to the Yamaha 850cc engine used in the TRX850 and mk2 TDM850 in the mid 1990s and the XT1200Z engine in the late 00s. The 1996 TDM was my first big twin and the 2010 XT1200Z was my third. Fond memories of both bikes.
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Sun Feb 04, 2024 7:46 pm (Last edited: Sun Feb 04, 2024 7:49 pm)
Zitat von wessie im Beitrag #2 But the art history major in him has him doing his research. He appropriately credits Phil Irving with bringing the idea for the 285 deg optimal twin firing sequence to Triumph in 1962 as a 270 degree manufacturing concept. First bikes were late 60s via Dick Cookson. Good article in April 1994 issue of the British magazine Classic Bike - originally 2 pounds 10 and available from the Magazine Man website for £6.75. It is titled: More Torque, Less Vibration, and recounts Dick Cookson's 284.5 degree crank conversion. The article also cites the early 90 deg (270 degree) cranks used in BSA roadsters by CRMC. (Any one else old enough to remember those discussions in high school shop class that had us running to our trigonometry teacher for confirmation?) So yeah - a lot of earlier bikes with 90 deg (270 deg) firing order including the Yamahas in their technology battle with Honda - but his point was that manufacturers didn't "sign on seriously" until about 30 y after Cookson - so about 1999. And of course he cites Euro 5 as the big impetus to revival of the 270 (90 degree) twin. And the final point was that 60 y later - the Irving - Cookson ideal of ~274.55 deg of the 1960s remains the realm of a custom cam shaft - until manufacturers start computer printing molds (or the equivalent), in what he predicts will be another 60 y. “A good man always knows his limitations.” |
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Tue Feb 06, 2024 11:01 pm (Last edited: Tue Feb 06, 2024 11:01 pm)
Wed Feb 07, 2024 4:19 am (Last edited: Wed Feb 07, 2024 4:19 am)
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Becoming well aware of the market failures of r18's and the shade this forum will keep on the model, nothing really hammers home the point as the fact I've yet to see a single one in person. Ever since I've started paying attention to bikes and riding back in 2018. never saw one.
Year-round riding enthusiast i.e. seasonal motorcycle popsicle.
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Zitat von Valks im Beitrag #8 I've seen plenty around St. Louis, though not as many as sold. Shocking how many Honz has sold out of Gateway. For a while, it was more than all the other dealerships combined. BMW North America incentives were huge and the marketing found it's demographic - especially at prices half that of an equivalent HD model. It's just a different culture. Still can't get over the apologies one owner made to the dirt riding service manager about the dust on his immaculate R18, in for service. His neighbor was mowing the lawn and, the R18 owner didn't have time to wipe it down before riding to the dealership. Everyone tried to look as sympathetic as possible..., but.... Still - the point is to ride one and feel all the asymmetric forces at play in the pistons and elsewhere. Even if you just sit on one and rev it up, you can feel it move on the flywheel axis. Physics in action.
“A good man always knows his limitations.”
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