Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: riffraff on May 21, 2010, 11:19:59 PM
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Twin cylinder 250, wish I read Japanese
(http://www.mxworksbike.com/images/32_1024.jpg)
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And another, "Note the rotary valve on top of the motor. This featured two rotary disks that simultaneously varied the intake and exhaust timing as the RPM changed."
(http://www.mxworksbike.com/images/30_1024.jpg)
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The twin has been featured in VMX magazine a while back. I doubt the 'variable' aspect of the disc timing, but it's still the only disce valve Honda I have ever seen. I'll get my Japanese operative to give me rough translation.
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It's a pity they were so anti 2 stroke :'(
Imagine what might be around today if they let their engineers do what they do best ;)
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I don't know the story behind this, but aren't twin-cylinder bikes against Da Rulez?
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Who cares Jetz ? ???
As a design exercise i think it's brilliant.
I bet everyone here would love to have a go on something like that.
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Oh yeah, I'm not doubting that. I'm just saying, we can't necessarily blame Honda for axing this thing, when they might have actually wanted to enter it in serious racing competition, but weren't allowed to. As does everyone else, I would love to know how this craziness goes.
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(http://i84.photobucket.com/albums/k13/fiveohstangbucket/honda_rc125m.jpg)
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Man that front end just blows my mind, I would venture to say the unsprung weight is a fraction of traditional fork bottoms of that era, it just seems like the long way around to me but I bet its PLUSH MR. ROBOTO
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I remember that style front end, believe it was the Ribi, got a picture somewhere of DeCoster with that style front end on his factory Suzuki
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(http://motorbikearchives.com/images/thumbnails/features/1979%20DeCosters%20Suspenders/1979-DeCosters-Suspenders-0_ae34e7358a39e2ab31a5b0f3fd5220b3.jpg)
"Suzuki's new motocross front suspension raised a lot of eyebrows during this year's GP season, but it didn't inspire any imitators. One look at the complicated system of links, struts and shock absorbers developed by Valentino Ribi with the cooperation of Ohlins dissuaded most everyone. Roger DeCoster even switched back to a conventional telescopic fork near the season's end after adopting the Ribi suspension as his own pet project.
But as DeCoster told the respected English publication Trials and Motocross News, the switch was caused by a lack of development time rather than any disappointment in the system itself. Indeed, the suspension had been calibrated to reduce trail under compression just like a standard fork. There was not enough time to produce the suspension's potential combination of constant trail and adjustable anti-dive during the usual two-week interval between races.
DeCoster commented that the Ribi suspension worked noticeably better than a telescopic fork and was less tiring on his arms. Only the weight of the systemâ??aggravated by the use of Ohlins dampers designed for rear suspension useâ??bothered him. "
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If you watch On Any Sunday, you'll notice that quite a number of bikes long before these had odd front suspensions which, while not exactly like this, were pretty similar. A lot of riders liked them because when you hit the front brake, the bike didn't dive. Sometimes, the nose actually went up a bit, which left one with lots of travel left-over to take braking bumps and crazed Joel Robert fans as they laid in front of you to slow you down. :)
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friend of mine back in the 70's had a DKW with the leading trail front end
(http://motorbike-search-engine.co.uk/classic_bikes/dkw_125.jpg)
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I think it was either Gilera or Aprilia that campaigned a 125 twin in some GPs around the Gaston Rahier / Akira Watanabe era of GPs.
Twins were rapidly banned, as bringing a potentially damaging level of costs to MX racing...!
Yamaha tested with a twin 125, and of course Honda had their twins in both 125 and 250 capacities. I think they used them for a time in the Japanese nationals. Twins were banned until Aprilia came out with their twin 450s / 550s. It's amazing how quickly the rules can be changed, especially when the main factories don't see the new bike as being a threat. I think now there is a 'gentleman's agreement' between the big factories to not pursue twins. Mind you, I think you'll see KTM and perhaps at least one Japanese factory come up with a 450 twin for Rally / Raid racing, with how well the Aprilia did in the SA Dakar. Probably the most exotic MXers ever made were campaigned the the J Nats - and you still see the trickest bikes there. Honda, for quite a few years experimented with CV transmissions on some works 250s - the nature of which was shown , ironically in Honda's patent application for their internal gearbox DH bikes that Greg Minnaar used to win the DH World Cups.
It was a variable dog bone /scissor link set up, that I've got a patent listing copy somewhere in my workshop - it was about 100+ pages of very interesting stuff. The funny thing is, the works Honda DH bike gearbox ended up , in its last few incarnations, as little more than a internal derailleur / sprocket cluster set up. It was hard to top something as simple as a system just derailing a chain onto a variety of sprockets. But there are few things that can stress/ prove/disprove the action/ feel and power transmission/efficiency of a drive line than the (in relative terms) ultra high torque and low revs of 2 human legs.
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I've got a DKW with the Earles fork in my collection.I was told that back in it's day that front end was the hot ticket in the desert.
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friend of mine back in the 70's had a DKW with the leading trail front end
Man thats a bitchen looking DEEK they made 2-stroke cars like Maico did I got to rebuild a DEEK tripple once I did a little tweeking here and there and it would light the front tires up!!! What a gas
(http://motorbike-search-engine.co.uk/classic_bikes/dkw_125.jpg)