Topic: 76 CB750K chopper. (Mod, please delete the other proj thread referenced inside!)

[TCSOHCB750CAFE]

Aight. So I had a cafe project going with this, but ended up picking up a GSXR750L (1990) to streetfighter, so I've got a good performance bike now.

So.... instead of junking this CB, it's getting a chop setup.

(Moderator, please delete this thread as it's no longer a valid project: http://forums.sohc4.net/index.php?topic=71654.0)

I got some work done recently on the tank. So far, this is the main part of this project.

It's an old Wassel Banana tank. Condition was pretty poor when I got it.

It's getting some more body fill and sanding, then a coat of pearl white, then scales under candy red in the center top and lower side portions with a nice fade.

The holes get some brass window inserts threaded in. They come from hydraulic systems.



Next update will be more on the tank, bracing the frame for cuts, hardtail and extending the backbone, doing a single seat tube, and building a real simple girder fork.

Please stand by.

[Ricky_Racer]

Cool. Very "Steam."    RR

[mystic_1]

Woah, me likey!

Moar please!

mystic_1

[hapakev]

very intereshting!

[TCSOHCB750CAFE]

There's more to come!

I started the jig for the hardtail that I want to build today.

I gotta get a few pieces of hardware that are proving elusive for how I want to do it, but once I do I'll post up.

-J

[TCSOHCB750CAFE]

Gettin JIGgy with it.

[TCSOHCB750CAFE]

Started cutting the frame and sorting geometries....

[hapakev]

I like it!  That is a mean stance.

[TCSOHCB750CAFE]

Framework started.





Tubes extended and rear half of frame minimized. Everything is long in these pics. Nothing has been trimmed to spec yet. Will update again soon.

[mystic_1]

Nice   Waiting with bated breath.

mystic_1

[bathcollector]

Framework started.





Tubes extended and rear half of frame minimized. Everything is long in these pics. Nothing has been trimmed to spec yet. Will update again soon.

Where you have joined the top backbone tube, have you put tube inside to brace the join at all ?? Tube should not be joined 90 deg, cut it at 45 deg and you have more weld area and less chance of a fracture, i know from experience this to be true.

[TCSOHCB750CAFE]

No, it's slugged with solid bar stock at the joint. Nothing is welded yet, it's tacked for measurement sake. Have to start on the hard tail, so I need to know where my points lay.

Your joint at a 90* on this tubing would be close to 4.5” around.

Cutting the tube at 45* would increase joint a small amount, but not enough to make a big difference in terms of cracking.

I'm quite confident, in my own experience, that when welded properly, a 90* tube joint with a slug is MORE than capable of handling the loads required in this capacity and more.

Another thing, I would assume you are MIG welding your joints? I say this because MIG welds are MUCH more prone to cracking, fracture, fissures, etc. than TIG. If possible, TIG your joints, give them a little preheat, and if you can find heat bags, use them once your weld is in to slow down the cooling process. It will help.

[bathcollector]

I gas welded mine, had a tube in it and it still broke right across the joint ? All my other welds bar the rear axle plates that were stick welded were gas welds, no other welds let go in 41000 kms of riding. The only thing holding my frame together was the saddle mount i had built into the fatbob gas tanks, rode it home 400 miles broken.

[TCSOHCB750CAFE]

I gas welded mine, had a tube in it and it still broke right across the joint ? All my other welds bar the rear axle plates that were stick welded were gas welds, no other welds let go in 41000 kms of riding. The only thing holding my frame together was the saddle mount i had built into the fatbob gas tanks, rode it home 400 miles broken.

You use the term "gas weld". I assume you mean MIG welding. MIG is REAL PRONE to cracking when you back it up like that at a joint. The problem is that the backup you use pulls a lot of heat away from the joint while you weld, causing less penetration at the weld. The issue really is that the weld will still *look* PERFECT though. It's the reason MIG welding isn't often used for real structural stuff professionally, giving way to stick or flux cored dual shield welding. Better penetration. Preheating can help, but can also cause a lot of warpage.

TIG is really the best way to go on something like this if you have access to one. You can use a little preheat, and really watch the parent metal go fluid and puddle up nice before tossing filler in. :thumbup:

[bathcollector]

I gas welded mine, had a tube in it and it still broke right across the joint ? All my other welds bar the rear axle plates that were stick welded were gas welds, no other welds let go in 41000 kms of riding. The only thing holding my frame together was the saddle mount i had built into the fatbob gas tanks, rode it home 400 miles broken.

You use the term "gas weld". I assume you mean MIG welding. MIG is REAL PRONE to cracking when you back it up like that at a joint. The problem is that the backup you use pulls a lot of heat away from the joint while you weld, causing less penetration at the weld. The issue really is that the weld will still *look* PERFECT though. It's the reason MIG welding isn't often used for real structural stuff professionally, giving way to stick or flux cored dual shield welding. Better penetration. Preheating can help, but can also cause a lot of warpage.

TIG is really the best way to go on something like this if you have access to one. You can use a little preheat, and really watch the parent metal go fluid and puddle up nice before tossing filler in. :thumbup:

No, gas as in oxy/acetylene welding. I agree on MIG, can fool you into thinking it's a good weld when it's only sitting on the surface.

[TCSOHCB750CAFE]

And something from lunch time. Had some free time...



They don't get used, but I wanted to have them for mockup purposes.

[TCSOHCB750CAFE]

45 degrees rake? Check.

[TCSOHCB750CAFE]

[Ouch]

Your idea is beast!!! this is an intersting follower....

[TCSOHCB750CAFE]

[captaincrash80]

Man, I am really diggin that tank. GO GO GO!

[COMB2]

Yea the tank is bad ass

[TCSOHCB750CAFE]

Small update. Waiting for other parts, then this goes out for polishing.


And this came...

[Ricky_Racer]

TCSOHCB750CAFE, it looks like you did a really clean 45 degree rake without a stretch. Have you got any detail photos of the rake job you can post? Thanks!  RR

[TCSOHCB750CAFE]

I'm moving this Friday across the state, so the bike is all packed until then.

Once I get settled in and stuff tho, I'll do a writeup. Maybe I'll get someone who wants a rake done to send me their frame or something and document the process..