Commando engine in Featherbed

Some aren’t as simple as they first appear tho, like that green un, the primary drive and alternator set up, not to mention the belt final drive!

Some folk put a lot of effort, and talent, into making things look simple !

When you are all done with the Featherlastic, is it any better than a Commando frame?
I thought about this for a Special but it's hard to beat the Commando frame for a Commando motor. Light weight (27 lbs), soaks up the vibes and handles.
Its almost like they designed it to be that way!

Glen

Danno said:

I have to wonder why more Featherlastics weren't put together. The one in the lineup at the 50th Anniversary of the Commando show at Barber looked great. It appears to be a pretty simple build. Here's another;

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Jeandr's beautiful custom!

worntorn said:

When you are all done with the Featherlastic, is it any better than a Commando frame?
I thought about this for a Special but it's hard to beat the Commando frame for a Commando motor. Light weight (27 lbs), soaks up the vibes and handles.
Its almost like they designed it to be that way!

Glen

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The 27 lbs you mention does not include the isolastics, the engine plates or the swingarm. When you compare a complete featherbed frame to a complete Commando frame - the featherbed is lighter and handles better as well. Having said that - If I were to use rubber mounts I would opt for the Commando but I prefer the featherbed with a smoother, low vibration motor and reduced stress on the crank and cases. Instead of adding weight with rubber mounts - reduce the internal reciprocating weight to an extreme and have the best of everything.

Danno said:

I have to wonder why more Featherlastics weren't put together. The one in the lineup at the 50th Anniversary of the Commando show at Barber looked great. It appears to be a pretty simple build. Here's another;

Click to expand...

How is the headstock supported on this bike?
Does anybody know?
Cheers

This thread seems to have morphed from a Commando engine rigid in a Featherbed frame, to isoelastic mounting of a Commando engine in a FB frame.

A rigid Commando engine mount is straightforward, amounts to fabricating modified engine plates, and paying attention to the balance factor. Our frequent poster, ashman, is proof positive that a good bike can result.

The Featherbed frame does not lend itself to isoelastic mounting of an engine. The frame, by itself, is rather "springy", and depends on the engine, side plates and head steady to make the entire assembly strong and rigid. This was discussed in a previous thread .... see Reply #137 in <https://www.accessnorton.com/Norton...-against-all-engineering-princip.17675/page-7>

"Featherelastic" bikes have been built, but I doubt they can be thrashed thru the corners as well as a rigid FB. I would think hard cornering might very well be a "hair raising" experience.

Slick

also turned out not much of a demand or even many featherlastics out there

grandpaul said:

Jeandr's beautiful custom!

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That is stunning !

Jeandr, more pictures and detail (pretty please).


Cheers,

cliffa.

jseng1 said:

The 27 lbs you mention does not include the isolastics, the engine plates or the swingarm. When you compare a complete featherbed frame to a complete Commando frame - the featherbed is lighter and handles better as well. Having said that - If I were to use rubber mounts I would opt for the Commando but I prefer the featherbed with a smoother, low vibration motor and reduced stress on the crank and cases. Instead of adding weight with rubber mounts - reduce the internal reciprocating weight to an extreme and have the best of everything.

Click to expand...

I don't think the rigid setup will ever equal the Commando for smoothness, just as the Commando will never equal the smoothness of my Triumph with its twin balancing shafts.
It all depends on what you can live with, and to a large extent, how far you ride in a day.
I like the Featherbed because of the history, the look of the frame and the ridiculously light steering.
Which frame makes the better handler is tough to say. They both handle well.
I think Doug McRae proved that a Commando can go around corners quickly!
Ludwig proved that a Commando can be made very light, 300 lbs roadgoing bike.

Glen

The thing about a Commando motor in a featherbed frame is that it is not right, but it looks right and probably functions better than an Atlas. Whatever happens, you need to make a choice about how you intend to use the bike and set the balance factor to suit. For a lot of high speed work, the 72% BF is better than the 54% balance factor. For a commuter bike, the high balance factor would be a pain. I would not use isolastics with a featherbed frame. If you get it wrong, a problem might come from nowhere and grab you by the throat. In fact, the way my Seeley 850 feels with it's rigicly-mounted motor, is part of the adrenalin rush.

cliffa said:

That is stunning !
Jeandr, more pictures and detail (pretty please).

Click to expand...

If you go to the "member's projects" section, it is one of the earliest ones!

I have a friend who has an Atlas which has a 79% balance factor. That is a really great bike to race - a really big adrenalin rush. The weight distribution with the sloping Commando motor should be better.

texasSlick said:

This thread seems to have morphed from a Commando engine rigid in a Featherbed frame, to isoelastic mounting of a Commando engine in a FB frame.

A rigid Commando engine mount is straightforward, amounts to fabricating modified engine plates, and paying attention to the balance factor. Our frequent poster, ashman, is proof positive that a good bike can result.

The Featherbed frame does not lend itself to isoelastic mounting of an engine. The frame, by itself, is rather "springy", and depends on the engine, side plates and head steady to make the entire assembly strong and rigid. This was discussed in a previous thread .... see Reply #137 in <https://www.accessnorton.com/Norton...-against-all-engineering-princip.17675/page-7>

"Featherelastic" bikes have been built, but I doubt they can be thrashed thru the corners as well as a rigid FB. I would think hard cornering might very well be a "hair raising" experience.

Slick

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I fully agree with you on this Slick, the Featherbed frame is dedsigned to be rigid and having a isoslastic motor in a frame designed to support the motor solid in the frame, changing to isoslastics would change the whole concept of the Featherbed design and of course change the way it handles.
Maybe why we don't see to many isoslastic Featherbeds, I looked into it when they first showed on the internet and the way things were changed you couldn't really call them a Featherbed, if you wanted to build one you have to build the frame from scratch but then there be so many changes to it that it be no longer a Featherbed frame.
The same as some who put bigger motors in them and once they have to mod the frame to make them fit just changes every thing.
I was thinking of building a one off special with my Slimline frame with a EVO Sportster but hacking into the frame was the turning point that put me off, so now building a Dommie Cafe racer.
What most people who have never rode a Featherbed really have no idea how they handle and they do take a bit of time to understand and get use to how to push them through the corners, but once you get to know how they work its like your stuck on rails they work so well, sometimes I push my Norton so hard through the corners and I got to look back to see if I did go through that corner, its a amazing feeling and using the power of the motor to push it out of the corners, till you own one and learn how to ride it will blow your mind, and having a hot motor plays a bit part of it putting that power down.
You would not be able to do that with a rubber mounted motor in a Featherbed frame.

Ashley

grandpaul said:

If you go to the "member's projects" section, it is one of the earliest ones!

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pix are mostly gone
https://www.accessnorton.com/NortonCommando/café-commando-build-thread.7680/

84ok said:

also turned out not much of a demand or even many featherlastics out there

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Maybe because they didn't workout right, yes might have gotten rid of the bad vibrations but at what cost did it do to the handling and really that's what a Featherbed is all about HANDLING.

Ashley

I wonder what the original poster of this thread thinks of all of this?
A commando engine in a feathebed frame is in essence a modified bike so why not just modify your commando if you don't like the handling?
It's not hard to get it handling impeccably as shown out on the track and please don't blame the ISOs for bad handling , even the monocoque had ISOs fitted so unless all you have laying about is a commando engine and a featherbed frame then I'd say go for it otherwise just upgrade (align) the stock commando frame
My personal preference is the 27° frame with 40mm offset yokes extra ISO under the gearbox , norvil type head steady ,koni shocks braced swing arm and very light apprilia wheels

I’m pretty aligned with Glen and Baz on this one it seems. I have, it fact I continue to have, ideas around an alternative frame for Commando power. Depending on mood this can range from Manx to Seeley, through to Rickman or even Rob North.

But each time I do it I wonder about two things, firstly I wonder about the vibration, I’m not thinking here about comfort, I’m thinking more about broken brackets, spilt oil or petrol tanks, etc that are quite likely when using a big cc / high CR engine at high rpm.

The second thing I think about, and this is usually at the forefront of my mind just after having ridden my Commando is... would I actually gain anything handling wise? It seems to me that for my own level of riding ability, the Commando frame is plenty good enough.

So, each time, after thrashing a potential project around in my head for a while, I tend to come back to the conclusion that, perhaps, just perhaps, the best frame for a Commando engine is... a Commando frame...?!

Or maybe get a Norton Atlas?
Just don't start the engine!!

Wow - this has gone wildly off topic!

I was watching this with interest until the Triumph and Harley engines paid a visit to the post.

I am stalled on my commando engine/featherbed project due to lack of funds.

@baz a good question regarding the headstock.

Here's what we have done on my project:

gtiller said:

Wow - this has gone wildly off topic!

I was watching this with interest until the Triumph and Harley engines paid a visit to the post.

I am stalled on my commando engine/featherbed project due to lack of funds.

@baz a good question regarding the headstock.

Here's what we have done on my project:

View attachment 11803

Click to expand...

That looks excellent
I take it the engine is rigidly mounted ?