Topic: Aluminum frame.

[Xnavylfr]

I wouldn't think the CB750 engines , the way they currently mount would be strong enough ,BUT if you had mount points from the head to help support the weight it could be possible.
 Here's another coal to throw on the fire!! What about a CARBON FIBER COMPOSITE frame???

Xnavylfr(CHUCK)

[hooverhonda]

Thought about that chuck. One of the guys I work with used to make racing car frames out of carbon fiber and suggested that. However I know absolutely have no knowledge of carbon fiber. So that would be a project for down the road.

Sean

[Bailgang]

How about the use of square or rectangular tubing that I see many sportbikes use? Even when keeping the lines of a stock frame it would definitely have a unique look. The only problem I see though is making the bends and not collapsing the radius without specialized equipment.

[crazypj]

Around 1989, Suzuki used an aluminium swing arm on DR350 with front and rear sections bonded together
 the bolts were only there because market survey showed people wouldn't trust bonded swing arm connection. I've never heard of a single failure, even after the bolts were removed.
However, it's well known that the steering heads will 'fall off' 2006~ GSX-R 1000 due to inadequate weld penetration and bad design.
The 'fix' is to glue and screw strengthening plates around steering head.
 The excuse for the failure was wheelies and stoppies although the one I saw was just poor welding with just about zero weld penetration into parent material plus a butt weld with zero overlap or mechanical connection (I cut up a scrap frame from earlier model, that had a 'step' to sleeve parts together)

[Duke McDukiedook]

Meh, just build a chomoly frame and be done with it. It sounds like Aluminum would be a huge hassle.

[hooverhonda]

Not for me dukie. It's like second nature welding aluminum.

Sean

[davis96]

http://www.speedmetalcycles.blogspot.com/?m=1
Dave at speed metal cycles just built an entirely aluminum rigid panhead frame, including factory castings from aluminum.

[crazypj]

Wonder how long that's going to last?
It can't possibly be as strong as the original steel frame, plus, vibration will work harden it.
Can't remember if it was Chrysler or GM that did tests on alloy vs 'steel' con-rods, the alloy has finite life, 'steel' just about infinite used at same rpm
As for aircraft, they also have a max flying hours, then they are junk, sections of fuselage have failed in flight so it isn't a valid comparison to motorcycle frame

[lucky]

Lots of the tubular structures used on airframes are 4130 chrome moly steel. If you look at modern aluminum bike frames you'll see the engine is a structural member and you'll also see  large sub frame diameters to make up for the weaker material.

Riveted, bolted and bonded tubular aluminum structures do away with temperament welding issues. You just can't get the aluminum welded area as strong as the unaltered parent material. You can do anything you want with the stuff  welding, it's  difficult to maximize strength to weight ratio. Cool looking is cool looking regardless to the frame color however there is a certain satisfaction in doing something different to be set apart from the others.

rt

I had a job building tubular chromoly steel frames for aircraft engines.
I built them from scratch. I TIG welded them. They not only passed all tests but went 6g's past load limits and only distorted 1/4 inch. No welds separated or fractured.

BTW.. I am a certified welder and a certified welding inspector through the American Welding Society.
I was a jet engine mechanic in the Air Force and worked on C-130's and F-106 Delta Darts.


Aluminum aircraft frames are rated for so many hours then scraped.

I am sure you can build a aluminum frame for the CB750.
You will not be able to attach the kickstand the same way as they did on the steel frame. Might as well make an aluminum oil tank too. And an aluminum gas tank.
You can buy aluminum handlebars or titanium bars.
Then you can buy titanium exhausts or make them.
Aluminum wheels from a CB750A.
If you use square tubing for the frame it is 16% stronger.

[lucky]

http://www.speedmetalcycles.blogspot.com/?m=1
Dave at speed metal cycles just built an entirely aluminum rigid panhead frame, including factory castings from aluminum.

Very nice work.

[lucky]

Meh, just build a chomoly frame and be done with it. It sounds like Aluminum would be a huge hassle.

Smart man.
Also the CB750 frame is only 1/16 thickness, so going to chromoly will be a much stronger stiffer frame. You would do away with all of the stampings.
I would use the same design and measurements as the XR750 Harley Davidson and have a world class bike.

On the other hand just buy a XR750!