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ghoti

Anyone know the history of the twin headpipe?

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Just a guess, but wouldn't it have something to do with having a single down tube to use as an oil tank? If there were only one exhaust port, it would have to be larger and centered which would require the down tube to be split like on the CR500. I'm sure there are other reasons. :applause:

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Honda 's first use of the twin head pipe was on the XL250 in '78/79. An XR version was also launched. It was the 2nd generation of XL's (replacing the famous XL 350) and the first of the large displacment XR's. A 500cc bike followed, then a couple versions of the 600, a really fun 200 and the short lived 300 only to be followed by the 650L and R. The Yamaha TT500 came out at the same time. It was a great 2 years for Honda--they also launched the all red CR250--second generation 2 stroker. I raced both of them at the time!

The Mags loved it and said it was introduced to allow a tighter curve on the header.

While we are at it:

the twin pipe -- with one on each side -- was not a Honda invention. Husqvarna did it 15 or so years ago. The mags hated it.

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A better scavenging effect is had by a four valve head with the twin head pipe,i think.

The mid 80's te/tc 510 had twin mufflers but did it have twin headers i'm not sure,my elder brother owned one BRIEFLY very briefly he hated it..

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When Honda debutted the 4 valve head on the Honda XR serries they needed to do the twin headpipe because they had two exhaust ports, and two intake ports. The original XR500R and XR600R/l all had twin carbs, one for each port, and twin headpipes one for each port. The XR serries went to a single carb for many reasons, mainly for tuning and esier starting, in 1989 or 90. I have a 96 XR600R and it starts very easily and runs very strong. The reason for this engine configuration is you get the best of both worlds, way snappy bottom end torque, and mid and top end. Try to find another bike from the 80s-90s with one headpipe 4 stroke that has the power of an XR...can't do it. Unless you choose a YZF which is cheating because it is a reace bike not an off road bike like the XR serries.

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Try to find another bike from the 80s-90s with one headpipe 4 stroke that has the power of an XR...can't do it. Unless you choose a YZF which is cheating because it is a reace bike not an off road bike like the XR serries.

Husky TE610 had heaps more power,the KTM 620 had more the old rotax motor in KTM'S,ATK's and CCM's had more power.I know some where twin headers at times but it was still the same donk in them.

But other than that you are right.

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Hey Happy, that 2 headed pig would be right for a thread about two carbs - as in INTAKE. What we're trying to talk about is two EXHAUSTS.....but that was pretty funny man!! Now please don't go looking for a picture of some pig with two buttholes!!! LOL....

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all had twin carbs, one for each port

the twin carbs were actually for the seperate fuel circuits. The left hand carb was the pilot and low end circuits and the right hand carb was the top end circuit. If you had the carbs off of the bikes and moved the throttle mechanism, the second carb would not start to move until the first carb was half way through the stroke.

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A better scavenging effect is had by a four valve head with the twin head pipe,i think.
That was the basic theory behind it. Twin pipe singles go back to pre-war racers of the 1930's, and like the 4 cylinder motorcycle engine...was not invented by Honda! :excuseme:

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Try to find another bike from the 80s-90s with one headpipe 4 stroke that has the power of an XR...can't do it. Unless you choose a YZF which is cheating because it is a reace bike not an off road bike like the XR serries.
These are different generations of bikes.

No YZF's in the 1980's....not even more most of the 1990's! As for a "reace" bike...how many YZF's have won the Baja 1000? Unless motocross is the only form of motorcycle racing? :excuseme:

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Yeah the twin header pipes definitely flow better which makes the engine more efficient, but it also means the exhaust itself will be slightly heavier. Thus, Honda have gone back to a single header with the CRF's to shave weight. As far as XR's having the best power goes, there were always plenty of other faster bikes around (ktms,huskys,husabergs spring to mind) -they never really were the HP kings. Even Yamaha 's TT range made similar horsepower numbers. Where the XR's shine is that they did everything else acceptably well eg handling, suspension, reliability, servicability and general appeal.

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