Topic: 76 CB750/GSX-R750/CBR600F2 Hybrid Build.

[Retro Rocket]

Build an egli style frame, we have a member {Mec} here thats already done it.... You would need to widen the tanks tunnel a little to fit the frame...
http://motosfrance.free.fr/img/egli/egli1.jpg

You could build the subframe to suit....

[SOHC4 Cafe Racer Fan]

Build an egli style frame, we have a member {Mec} here thats already done it.... You would need to widen the tanks tunnel a little to fit the frame...
http://motosfrance.free.fr/img/egli/egli1.jpg

You could build the subframe to suit....

Mick,

That Egli has oil in the frame, right?  Very trick.

[Retro Rocket]

Build an egli style frame, we have a member {Mec} here thats already done it.... You would need to widen the tanks tunnel a little to fit the frame...
http://motosfrance.free.fr/img/egli/egli1.jpg

You could build the subframe to suit....

Mick,

That Egli has oil in the frame, right?  Very trick.

Yes, another bonus....

[Syscrush]

I just want to go on record as stating that I think that designing and building a frame/bike around a tank you like is a worthy and admirable goal.

Soichiro Honda wrote a couple of very compelling short essays on design, and what he has to say about the Buddha's eyebrow in this one reminds me of your project.

[Letze]

Build an egli style frame, we have a member {Mec} here thats already done it.... You would need to widen the tanks tunnel a little to fit the frame...
http://motosfrance.free.fr/img/egli/egli1.jpg

You could build the subframe to suit....

I saw a build with a frame like that, the guy had an awesome frame jig and build table. The angle on the carbs forces me to have the airbox up relatively high so a more traditional backbone creates a great deal of complications.

I just want to go on record as stating that I think that designing and building a frame/bike around a tank you like is a worthy and admirable goal.

Soichiro Honda wrote a couple of very compelling short essays on design, and what he has to say about the Buddha's eyebrow in this one reminds me of your project.

Thanks man I'll be reading through that tonight.

I'm consolidating several measurement documents and diagrams I have for the engine and frame concepts I have measurement data from about 4 different bikes I'm sifting through at the moment. The range of parts from various bikes I have making this project up make the bike sound like Johnny Cash - One Piece at a Time.

[Riceman]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

[SOHC4 Cafe Racer Fan]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

If you want to get hurt riding it. That aluminum tube cobbled together would not likely provide sufficient strength.

[Riceman]

Then use stainless or maybe a bracket to steady them.

[calj737]

Then use stainless or maybe a bracket to steady them.

Could use stainless, but why over mild steel? Chrome moly is probably a better choice than stainless, and nearly as light as aluminum. Could use aluminum, but you'd want at least 0.25" wall thickness, then welding it would take significant heat.

CroMo would be my choice for strength and weight and is very common today in lots of exotic bikes as the tubing metal. 0.083 thickness mandrel bent should easily do the trick.

Some of the Rickman 750s had no backbone, which seems to maybe offer you the space you were describing. I think the biggest challenge you'll face is incorporating the Honda motor into a suspended stressed member based upon where the factory mounts are.

I've seen folks fab brackets for the rear of the motor that tie into a backbone (eliminating the rear hoop and suspending the rear of the motor) and do the same in the front, but they always tie into a backbone and the "bracket" is quite substantial in billet. I am very interested to see how you solve it!

[SOHC4 Cafe Racer Fan]

Then use stainless or maybe a bracket to steady them.

Could use stainless, but why over mild steel? Chrome moly is probably a better choice than stainless, and nearly as light as aluminum. Could use aluminum, but you'd want at least 0.25" wall thickness, then welding it would take significant heat.

CroMo would be my choice for strength and weight and is very common today in lots of exotic bikes as the tubing metal. 0.083 thickness mandrel bent should easily do the trick.

Some of the Rickman 750s had no backbone, which seems to maybe offer you the space you were describing. I think the biggest challenge you'll face is incorporating the Honda motor into a suspended stressed member based upon where the factory mounts are.

I've seen folks fab brackets for the rear of the motor that tie into a backbone (eliminating the rear hoop and suspending the rear of the motor) and do the same in the front, but they always tie into a backbone and the "bracket" is quite substantial in billet. I am very interested to see how you solve it!

I agree with Cal about chrome-moly tubing. It'll give you better strength and lightness compared to mild steel.

Since you are using a modern motor you will not have the same mount constraints as with the 750 motor. Of course, as you know, you then need open space in place of the backbone to mount your carbs.

The engineering required definitely has my attention. Does your CAD program allow you to place the engine and carbs in empty space, then overlay the top shape of the tank, and then weave a frame around it using the mount points? Given the constraints, I think you will need to cut the bottom of the tank and create a new bottom to fit your frame and carbs.

[Retro Rocket]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

If you want to get hurt riding it. That aluminum tube cobbled together would not likely provide sufficient strength.

Aluminum tube frame.....

[SOHC4 Cafe Racer Fan]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

If you want to get hurt riding it. That aluminum tube cobbled together would not likely provide sufficient strength.

Aluminum tube frame.....

Yeah, Mick.      That tubing looks a little stronger than the 0.065" (16 Gauge) in the link.  The picture you have looks more like a Spondon frame.  Too bad even that frame doesn't have enough headspace to fit his carburetors which are angled more upwards.

[Retro Rocket]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

If you want to get hurt riding it. That aluminum tube cobbled together would not likely provide sufficient strength.

Aluminum tube frame.....

Yeah, Mick.      That tubing looks a little stronger than the 0.065" (16 Gauge) in the link.  The picture you have looks more like a Spondon frame.  Too bad even that frame doesn't have enough headspace to fit his carburetors which are angled more upwards.

Looks good though.....

[SOHC4 Cafe Racer Fan]

You could use this http://www.mandrel-bends.com/catalog/1-50-aluminum-2-25-radius-16-gauge-180-degree-mandrel-bend-646.html cut it up and get 4  22 1/2º bends to get the carbs to level out.

If you want to get hurt riding it. That aluminum tube cobbled together would not likely provide sufficient strength.

Aluminum tube frame.....

Yeah, Mick.      That tubing looks a little stronger than the 0.065" (16 Gauge) in the link.  The picture you have looks more like a Spondon frame.  Too bad even that frame doesn't have enough headspace to fit his carburetors which are angled more upwards.

Looks good though.....

I completely agree.  That frame looks bad-ass!!

[calj737]

Bloody stinking beautiful, actually!

[FunJimmy]

Spondon makes the coolest frames.
I want one. 

[SOHC4 Cafe Racer Fan]

Another possible way to go is to build a frame similar to a Drixton. Brent (bwaller) races one built by CMR Racing.  The frame design could accommodate the engine and allow open headspace for the carburetors.  You could then alter the 750SS fuel tank by adding an extension to the rear bottom like the following CB350 Drixton: