Topic: Rear hoop on a cb550

[work9to5]

So I ran into something interesting today when going to put a rear hoop / loop on one of my 550's. I found the stock frame tubes extend to different lengths when I chopped the rear horns off and exposed them. Havnt seen that before. Have done one hoop job before not on a Honda. I've measured it 10 times they are in fact different lengths. Pics attached

I've got two ways I can think of to go about this but if anyone has suggestions please lmk

1.) cut the hoop un even so that one end extends farther to reach where it needs to butt up. Use a rotary tool to trim back the un even side so I can get a good weld on there.

2.) cut back the tube. Cutting open from the tops evenly. Leaving the hoop the same lengths. And then pushing the hoop slugs into the "slots" I've created so I can get an even weld on both.

I'm leaning towards option 1. Structurally it sounds like it would hold better? But I've haven't done a lot of welding on frames especially where frame integrity is so important. So I'm asking you guys. Help appreciated.

The bikes one of my dailys, for those interested. Have been procrastinating on hooping her and I decided today was the day. She's 605 bored, hot cam, Showa gsxr front end conversion and a blast to ride.

[work9to5]

More pics

[calj737]

Trim the hoop ends so they take up the irregularity.

If you don't have a lot of welding experience, this project is not the right one to learn on. The stock tubing is very thin and will burn through rather easily with too much heat, and you need a good weld for strength. Squirting MIG snot that's cold is worse than not having any weld on there. It will just crack under stress and any strength you thought you had will be the source of an injury.

[work9to5]

Cal, thanks for the advice as always. I'm confident in my weld experience. Not a ton of experience but not a novice. I found it interesting that the frame tube lengths where different and thought I should post about it. I also couldn't find a detailed post about hooping on here so I thought I'd step by step it. To help my process and get some info out there. Going to run a bunch of test beads on the horns that came off to calibrate my heat setting (and wire speed)before doing the actual frame. If we didn't try things we weren't used to doing on the regular none of these engines would be fixed or these beautiful machines restored/created right 👍 I'd appreciate your advice in future posts, going to take it step by step and pic heavy it.

[CycleRanger]

Made in a Friday or a Monday. 

Honda was cranking out bikes as fast as they could back in the early '70's.
I'm sure they had a spec for what was tolerable for those tube lengths since the ends weren't exposed.

[westhewelder]

As a welder I'm with cal on the welding, but the supplied slugs should help act as a heat sink. As for fit figure out where the seat sit relative to the frame and cut accordingly it actually wouldn't be a bad thing that they are staggering.

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[SOHC4 Cafe Racer Fan]

Depending on the tail you are using, the hoop will not likely be seen.

[work9to5]

Irish, yeah that makes complete sense the the off set would add support. Didn't even think about that 👍

Sohc, I'm making the pan and seat to fit the hoop. Actually going to do a slim tuck n roll or diamond "brat" and wanted to leave as much of the frame visible as I could. But it will all depend on how this comes out n' cleans up.

I'm in the middle of my work week. Progress to come Friday!

[RAFster122s]

Unless you have limited travel, the first major pot hole that rear tire hits is going to have some nasty results and likely a wreck.  No room for the tire under full compression.

[work9to5]

Where the fender used to sit, was lower than hoop will sit. Had no contact over 4,000+ miles of riding. But thanks for the input