anyone got experience with commando engine in wideline frame with isolastics? if so any photos

Atlas Commando

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As a young man with no mechanical ability and virtually no funds, I acquired a Norton Atlas with a cratered motor and a Commando that had been wrapped around a tree. I drilled 3 extra holes in the back of the Commando primary to get the Commando engine to sit upright, and then just bolted things together. I wish I could recall what I did for a top motor mount, maybe stock Atlas? As expected, the thing was 'thrilling' but it was a buzzing anvil. Tail light bulbs were good for a few hundred miles, and soldered wire connections not much better. I sat the oil tank on a piece of inner tube and it held up, but the gas tank developed a habit of cracking at the seams. If I really rev'd it hard my feet would slide off the pegs. It was a big part of my transportation for about a year, until the Commando engine dropped a rod and holed the cases.
I feel that my Atlas-Commando consolidation doesn't quite measure up to these other efforts.....
 
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All featherlastics are not the same. I have ridden the root beer colored one shown in previous. Handling is excellent. Bike rides smooth like a commando. Note that swing arm does not float with engine like commando. Bike that norton should have built.
If it works as good as it looks it can't be too bad. Here's another abortion to encourage Norton motors in Norton chassis;

North%20Alabama%20Vintage%20Club%20gathering%20June%205%202021%202021-06-05%20009-X2.jpg
 

Fast Eddie

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Seem plenty of single engined bikes go well on the strip too.

Also seen plenty blow up...
 

baz

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If it works as good as it looks it can't be too bad. Here's another abortion to encourage Norton motors in Norton chassis;

North%20Alabama%20Vintage%20Club%20gathering%20June%205%202021%202021-06-05%20009-X2.jpg
Exhaust looks like it's made from a bathroom towel radiator
Very handy
 

Fast Eddie

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Nice bike. Did Mr Degans make the swing arm longer to keep the wheelbase similar to a Featherbed?
Not exactly. The main geometry was copied from his ‘Dresda’ chassis, which in turn was copied from the Sid Lawton Aermacchi’s that Dave raced.
 

t ingermanson

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Why do people say that?
View attachment 80306
If you can fit two items in a single container, the container is too big or the item too small.

If nothing else, the 6-8" gap between the swingarm pivot and the final drive sprocket. Alternately, if that gap is closed, the center of gravity is too far back (but a Suzi 4ls brake certainly helps keep the CG forward! HA!)

Aesthetics are another concern, but are subjective. The handling effects are not subjective.

Please don't take it as a personal attack on your bike, as it's not meant to be. I prefer non-unit motors in non-unit frames for all the above reasons, as well as some squishy "general principle" quasi-logic. It's ok to disagree.

**Back to Isolastics on a Featherbed.**
I'd be quite interested to hear what others have done for a balance factor on Commando motors in a Featherbed, Iso or not. Stock Atlas BF? The JS reciprocating parts seem like a no brainer for a 750, but seem like you get less impact/value the smaller the capacity (Dominator/650 motors). The Featherbed Isolastics seem like a fun engineering exercise, but might make your head hurt for dubious results and/or other problems.
 

ashman

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Balance factor for my Commando motor in a Featherbed frame was done at 72% and works very well for my 850.
 

robs ss

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Some people talk about "balance factor" as if it is some magical way of smoothing the 360 degree twin (or single) when it is actually only trading vertical imbalance for induced horizontal imbalance. (okay - give or take 15 degrees for the "sloping" Commando)
The only "real" way to reduce vibration in these 360 degree twins (or singles) is to reduce the reciprocating mass - the source of the vibration.
Isolastics (which I admire, by the way) are only a way of covering up those vibrations.
 

grandpaul

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3 motorcycles met their end to assemble this piece of, well, I don't have a good name for it, so fill in your own blanks.
How could you know that?

I have built 17 bikes from SCRATCH, 3 of those were Tritons.

Not a SINGLE one of those was built by first disassembling a donor bike (not disassembled by me, anyway)
 

grandpaul

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Some people talk about "balance factor" as if it is some magical way of smoothing the 360 degree twin (or single) when it is actually only trading vertical imbalance for induced horizontal imbalance. (okay - give or take 15 degrees for the "sloping" Commando)
The only "real" way to reduce vibration in these 360 degree twins (or singles) is to reduce the reciprocating mass - the source of the vibration.
Isolastics (which I admire, by the way) are only a way of covering up those vibrations.
I don't think anyone was arguing that balancing the engine to a different factor was a panacea...
 

t ingermanson

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Some people talk about "balance factor" as if it is some magical way of smoothing the 360 degree twin (or single) when it is actually only trading vertical imbalance for induced horizontal imbalance. (okay - give or take 15 degrees for the "sloping" Commando)
The only "real" way to reduce vibration in these 360 degree twins (or singles) is to reduce the reciprocating mass - the source of the vibration.
Isolastics (which I admire, by the way) are only a way of covering up those vibrations.
Yes. I completely agree. I'll rephrase in an attempt mitigate your concerns.

The reports I've read (including the above linked one) have mentioned a rebalance, but have stopped short of providing a number, and none have included the super light piston/rod sets currently available.

So... when you put all the aftermarket lightweight hoohaws into your Commando lump, the reciprocating weight has changed, so the balance factor has changed, yes? Is it ok to leave the flywheel as is? Change to the stock BF accounting for the new lightweight whirly bits? Treat it as a regular Commando and match for the iso system, if it exists on your Featherbed? Change to match the rigid mounted Atlas? A different one altogether?

Do the lightweight piston/rod sets completely eliminate the "need" for isos on a standard Featherbed with a 750, 850, 920, etc motor?

Since both adding an iso system to a Featherbed, and balance factors are suck-it-and-see scenarios, it might be constructive to the OP (or anyone else contemplating this) to shed a bit of light on this variable. There are smarter people than I who've been messing with this a lot longer than myself, hence the questions.
 
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