Topic: 79 cb650 swingarm on 77 cb550 ?

[steeldoncb550]

Question for you all. I was working on my swingarm in prep for sandblast and powdercoat and while in a vise to hammer out the shock bushings, I squished it. It’s not longer round. I have the opportunity to buy an entire 79 cb650 (minus tank and seat) and wondering if the swingarm is the same.

[steeldoncb550]

Hopefully someone can answer to this soon

[Scott S]

 The 650 swingarm is about an inch and a half longer than the 550.

The 650 swingarm is ALMOST a direct fit with the 550 frame.  Only issue is with the pivot bolt.  The 650 swingarm pivot bolt is 16mm, while the 550 swingarm pivot bolt is 14mm.  That leaves you with 2 options.

1.) Drill out the 550 frame to accommodate a 16mm swingarm bolt (which I do not recommend)
2.) Replace the bearing sleeve in the 650 swingarm so the ID is 14mm.

[steeldoncb550]

The 650 swingarm is about an inch and a half longer than the 550.

The 650 swingarm is ALMOST a direct fit with the 550 frame.  Only issue is with the pivot bolt.  The 650 swingarm pivot bolt is 16mm, while the 550 swingarm pivot bolt is 14mm.  That leaves you with 2 options.

1.) Drill out the 550 frame to accommodate a 16mm swingarm bolt (which I do not recommend)
2.) Replace the bearing sleeve in the 650 swingarm so the ID is 14mm.

Thanks for the reply. I will find myself a 77-78 swingarm.

[754]

Don't even Need to do that. Get two bushings made 16mm OD 14 mm ID, say 40 mm or so long, make it sa 2 thou over. Drive it in carefully, ream with a split bokt and emery if you dont have a reamer.

[bryanj]

Problem is swingarms pivot on the collar NOT the bolt.
The bolt when done up tight traps the pivot collar between the frame sides.

[JJbigshoe]

I just did this on the 79 CB550 I'm building. I enlarged the frame holes to accommodate the 16mm bolt. I have much tighter tolerances in the 550 after reaming the frame holes than what they are in the donor 650. I don't foresee an issue with it but I guess I'll know for sure once I get some wheels on it. And an engine, gas tank, rearsets, signals, lights, forks...

[RAFster122s]

How do you tell the difference between the 77-78 swingarms from the 74-76 swingarms?
 Is the K swingarm the same as the F swingarm for the respective years?

I have a swingarm I bought from a fellow member I need to pick art with...it has the chrome chain guard , which isn't in the best of shape as it is cruddy on the underside and it had been sannded or steel wooled leaving scratches on the outside. It would be fine  if you were to powder coat it. The swingarm had been mounted and there are a few spots the axle bolts marred on the swingarm. It was powder coated a gloss black.
It has been rebuilt with the needle bearings instead of the stock bushes and it has a zero fitting in the center. The needle bearings kit goes for over $100 from Z1 Enterprises the last time I looked.
It is a 550 arm but the 74 K I have had good bushes and I think this spare is off an F bike or the late 77-78... I don't remember now.

Sorry not trying to thread jack figured the answer would be pertinent to the Original Poster.
David

[Scott S]

 If it has the chrome chain guard, it's from an F model.

[Bankerdanny]

How do you tell the difference between the 77-78 swingarms from the 74-76 swingarms?
 Is the K swingarm the same as the F swingarm for the respective years?

I have a swingarm I bought from a fellow member I need to pick art with...it has the chrome chain guard , which isn't in the best of shape as it is cruddy on the underside and it had been sannded or steel wooled leaving scratches on the outside. It would be fine  if you were to powder coat it. The swingarm had been mounted and there are a few spots the axle bolts marred on the swingarm. It was powder coated a gloss black.
It has been rebuilt with the needle bearings instead of the stock bushes and it has a zero fitting in the center. The needle bearings kit goes for over $100 from Z1 Enterprises the last time I looked.
It is a 550 arm but the 74 K I have had good bushes and I think this spare is off an F bike or the late 77-78... I don't remember now.

Sorry not trying to thread jack figured the answer would be pertinent to the Original Poster.
David

I don't know that there is a difference, but here's the swingarm on my '75 550F

[bryanj]

If you look at the end the K has a removable piece like the 750 but the F has a closed end

[Bankerdanny]

If you look at the end the K has a removable piece like the 750 but the F has a closed end

I know that my 77 550K had the closed loop like the one on the F. My '74 550k roller had the removable piece kind.