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I'll confess right here I'm double-posting @BritBike, but I doubt all you guys go there so...featherbed frames have a big rep. for excellent handling, but I've never been on one. I realize they are out-classed by modern sportbike frames, but these are not vintage(same with forks).Could some of you guys that have experience with featherbed frames, especially in regards to specials, tell me what they do or don't do better than other frames of the day? How do the repro featherbeds compare with the originals? I came across a pic. from the mid-ohio meet of a featherbed frame w/ Kawasaki 500 triple 2-stroke engine, wonder if that combo. cures the notorious ill-handling of the H1?Hoof-hearted?
 

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I'll confess right here I'm double-posting @BritBike, but I doubt all you guys go there so...featherbed frames have a big rep. for excellent handling, but I've never been on one. I realize they are out-classed by modern sportbike frames, but these are not vintage(same with forks).Could some of you guys that have experience with featherbed frames, especially in regards to specials, tell me what they do or don't do better than other frames of the day? How do the repro featherbeds compare with the originals? I came across a pic. from the mid-ohio meet of a featherbed frame w/ Kawasaki 500 triple 2-stroke engine, wonder if that combo. cures the notorious ill-handling of the H1?Hoof-hearted?
Ah, yes it does. They didn't call the Hi & H2 "Widow Makers" for nothing (I have scars to prove it from my H1). The featherbed frame was designed in 1949 for the race bikes because of it's dual hoop design that made it incredible strong and therefore excellent handling on the racetrack. They claim there are 40' of tubing in a featherbed frame. While the Norton Manx was not the fastest bike around in the mid 70's it was still a world class handling bike. The H1 & H2 on the other hand were extremely fast for the times but their frame design was weak and cause tank slapping handling when made to corner under speed (mine was destroyed due to this). The solution for some was to graft the H1 or H2 motor into the Manx Featherbed frame and have the best of both worlds, an extremely fast motorcycle that actually handles. My brother owns a Kawaton, Kawasaki H2 750 in a Manx frame. My H1 motor went into a go kart.
 

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Hey Marc. I saw a copy of the book "Century of Speed" today. The Metro is in it. Featherbeds. You won't find a finer handlng frame anywhere. Sportbikes are a different kettle of fish. The frame, suspension, tires etc are from a different sphere. Featherbeds came in three different types of tubing. Standard featherbeds were your basic mild steel. Internationals used a high carbon steel and the Manx frame was Reynolds (not to be mistaken for chromoly). All had the same wonderful handling characteristics.

The nice part is the frame will hold just about anything. The only problem is a small engne will look lost in them. I'd love to see how the H1 looks in a featherbed. I saw a photo on another forum of someone putting an XS650 in a featherbed. Looks like shit. As a unit construction it is way too short. Even unit Triumphs look all wrong. But that's only my opinion. I should talk! I have a Weslake speedway engine in my Norton. Looks lost. But its fast (relatively).

What do the do or don't do? They handle better than anything of the day and for many years after they ceased production. And when it comes to tube frames they are still the standard. Repro frames are every bit as good. If you have extremely deep pockets you can get in touch with Bakker Frambou in Holland. They can make you a featherbed in titanium. Around 15,000 euros. This is mine with a Weslake and the engine despite being a 500 it looks tiny. The other shot is when it had a Manx in it. Looks a whole lot better.



 

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Hoofhearted, was it just a pic or a story with it? I'll have to check it out and let Bob know.
 

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It was a pic with a couple o sentences (speed etc.). Regardless its oh so cool to make it into the book.
 

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I raced a Triton owned and built by Randy Illg of Framecrafters, in the early 80's. It was very stable and tracked through the curves nicely.
 

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Not all featherbed frames are created equal. Racing evolves and as such changes happen. There are a pretty standard list of "refinements" that go into a racing featherbed so you can't just pull an atlas frame out of the garage, shove an engine in, and expect it to be race competitive in this day and age.

the nice thing s if you buy from a place like unity equippe the new frame will have all the standard racing mods.

However, you don't need a featherbed to get an h1 to handle. You can do it with kawasaki parts. The frame you need is the 1976 kh500 frame. It's stronger than all other h1 frames.
 

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if you haven't read this yet...this give you just enough information to be dangerous:
The Vintagent: REX McCANDLESS AND THE FEATHERBED FRAME

this is even more awesome:
Yorkshire Ferret: The Anatomy of a 1954 Works Norton Featherbed frame


Keep in mind a lot goes into the swingarm and forks as well. When the first featherbeds were designed norton roadholder forks were the best there were - but then there came ceriani/betor/marzocchi, and eventually we are up to modern cartridge forks. The swingarms started as oval tube, then tapiered tube, then box alloy.

If you ask me, a featherbed is wasted on a triple. The kawi triple engine came from an era when motorcycling had mostly evolved beyond the f-bed and was really beginning to dial in the relationship between the swingarm pivot and the steering head.

Also, while early h1's had the handling reputation, the 73-75 h1's were not as bad (they aren't great but none of the jap bikes from that era are all that great). A lot of it had to do with the open frame design in the rear on the early h1 (69-73) and the H2s (72-73) where the grab rail was actually a bolt on structural member of the frame.

denco used to put out a bracing guide for the early frames:


And then compare it to the H1R racing frame, you can see what's there to get one to handle:


BTW, Harris performance will make you an H1R racing frame if you really want your kawi triple to handle:
Gallery of Harris Road & Race Machines


pay close attention to the other things that went into the racing bike. Wheels, forks, etc....nothing is bog standard on a racing manx or an h1r all that stuff is special.
 

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They are great to about 80~90hp, swing arm mounts flex a little when you put more power into chassis (not serious though)
 

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Geets, the 75 may not have been as bad as an early one but 2 times nothing is still nothing. Mine was a 1975 and when throwing it from a left hand lean into a right hand lean would throw the thing into a serious tank slapping wobble. I ended up crashing hard doing that last time I rode the thing before totaling the thing out. That wreck is a whole chapter in the book my friends think I should write. It was an interesting night.
 

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pay close attention to the thing in denco's guide: bigger frame bolts help. this means the engine is a partially stressed member in the frame. On the later h1's the engine is rubber mounted, just so you know.

I have seen guys put kawi triple engines in 1980's Zx6R ninja chassis before. To me that's the move. Why the 1980s? because the frames are wishbone but use a lower steel engine mounting cradle that you can easily weld to if needed and therefore doesn't use the engine as a stressed member. With that setup you'd be pretty close to what a formula 1 (now motoGP) 500cc two stroke was in the early 1980s.
 

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Early Yamaha FZR600 , Suzuki Katana 600 or Suzuki GS500 rolling chassis, perimeter frame, all steel, upgrade suspension and it will be a nice bike
 

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Geets, the 75 may not have been as bad as an early one but 2 times nothing is still nothing. Mine was a 1975 and when throwing it from a left hand lean into a right hand lean would throw the thing into a serious tank slapping wobble. I ended up crashing hard doing that last time I rode the thing before totaling the thing out. That wreck is a whole chapter in the book my friends think I should write. It was an interesting night.
at least it would change direction as compared to say a Z1 where it took directional changes as light suggestions and filed them in the round file.

yeah the 73-75 frame still needs work. Even a 76 KH500 frame which added most of the bracing mentioned in denco's guide still needs work. But an early h1 frame you could feel wind up underneath you. I have a 1971 bare frame and I can flex it by hand in a lot of spots. I think where kawasaki made the mistake is they made the 73-75 engines rubber mounted and they still used the old small bolts which means the engine was now less than the stressed member it was before. They gave the neck extra suppot but didn't add support to the cradle, esp the needed cross braces (which they did add in 1976). The swingarm wasn't great either, too small. It's another part you can easily flex by hand. The whole frame has a tendency to wind up on you in hard cornering (the cradle tries to shift laterally) and when you transition it "springs" back to shape as you cross the neutral point - hence the wobble.
 
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