Featherbed or Commando Frame

Hi,

I have the opportunity to purchase a featherbed frame. The frame needs slight straigtening but is not major work. I've currently got a 750 commando engine. My intention is to build a racer. I intend on balancing the engine so vibration should not be a major issue with the older frame. I would however have to pick up a swing arm and the appropriate motor mount adapters to fit the old frame. Do the featherbeds handle remarkably different and is it worth the extra cost and effort?

Thanks

Madpiper,
While not firsthand knowledge, a good friend of mine is currently campaigning a Commando motor in a featherbed frame and is doing extremely well. He's a long time Commando rider (on the street) and a very smooth and talented rider. He swears by the featherbed. Although he's rebalanced the motor, he says the vibration at speed is still considerable. (Especially compared to the TZ250 Yamaha he also races). To be competitive expect to spend lots of money on things like a 5-speed gearbox, strengthened cases, quality headwork, good brakes, etc.

Commando in a featherbed frame

Madpiper. Check out this website!: broken link removed It's Kenny Cummings of NYC that builds a Commando engine in a featherbed frame for vintage racing. Cool website with lots of photos, facts and links...

BR
Niels

Yes,

That is the site that started my whole "predicament"! I have found a featherbed frame and I realize it will cost me more with some of the repairs and to upgrade the rear swingarm, motor mounts ect; but thats really what I'm after. From what I've read, they are a tighter handling bike.

The whole reason for development of the Commando and the Isolastic engine mount system was to get away from the vibration problems that were so dominant on the Atlas. If you put the 750 engine in a featherbed frame, you've got an Atlas. If it's an 850, you've got an even bigger problem.

Additionally, the Commando structural design gave about a 10-fold increase in torsional stiffness, keeping the front and rear wheels more accurately in line. Vertical stiffness increased by about a factor of 3x.

Provided the lateral clearances in the polyurethane discs that control side-to-side rocking motion are kept within specs, the Commando should out-handle a Featherbed by a facotr of at least three.

Of course the featherbed setup is going to provide a much shorter wheelbase and hence a quicker handling machine....

My CB400f is way more nimble than my Commando, easy to throw over into a hairpin at the track. Of course the Norton is more fun....I'd love to do a featherbed too, but maybe a 500 to keep the vibes down...you don't have to go that fast on an old machine to have a good time.

Good Luck!
Chris