Author Topic: Cb650c parts onto a cb550  (Read 1815 times)

Offline Mvward9

  • Newbie
  • Posts: 3
    • View Profile
Cb650c parts onto a cb550
« on: September 23, 2015, 10:55:01 AM »
Hello there,
I have a full 1981 honda cb650c and would like to start my first cafe racer build. I understand that the frame on the 650c dips down at the back so is not ideal. I have seen a 1977 cb550 f1 frame for sale and would like to know if I can swap parts, mainly- swingarm, engine, front end onto this frame?
I think this would be easier than modifying my current frame.
Will these parts fit?
If I have to drill out the 550 frame slightly to accommodate the 650 swingarm will everything else be in the right place, shock mounts etc?
Will the front end be a straight forward switch?
Thank you for you time.
« Last Edit: September 23, 2015, 11:17:56 AM by Mvward9 »

Offline Bryanj

  • SOHC Jedi
  • Posts: 5113
    • View Profile
Re: Cb650c parts onto a cb550
« Reply #1 on: September 23, 2015, 05:54:39 PM »
Can't be 100% certain but i think that most of what you want to do is easily possible but as it is not a common thing you will have to be the guinea pig and let us know

Offline Mvward9

  • Newbie
  • Posts: 3
    • View Profile
Re: Cb650c parts onto a cb550
« Reply #2 on: September 25, 2015, 10:07:39 AM »
Thanks for that, I'll let you know how it goes. From what I can gather of other peoples experiences with putting a 650 engine in a 550 frame is that it shouldn't be a problem. I just hope the frontend and swingarm are the same. 
I may well put a 550 tank on it too.

Offline andy120t

  • SOHC Expert
  • Posts: 273
    • View Profile
Re: Cb650c parts onto a cb550
« Reply #3 on: September 25, 2015, 09:14:43 PM »
My 650 engine went into the 550 frame without a fight.   I'm using a 550 swingarm so can't comment on that fitting or not.

Yokes into that frame - I use the link below to see if my bearings match up...(yours do, as far as I can see) so should be a straight swop:  http://www.customfighters.com/forums/showthread.php?t=22068

Upper: 26 x 48.5 x 15.2
Lower: 30 x 50 x 14.4

...the only question might be if the steering stem is longer on the 650....but a spacer or two under the top nut would solve that.

Using the above, I'm just in the processs of fitting R6 forks into my 550 frame.. (it's great what the internet can help you with!

As far as I'm aware the C frame is different and dips hideously in the middle..- but instead of buying a stock cafe racer seat - why not try to make/ or have made - a seat that fits the frame but still looks right for they style you want? Might work out cheaper or less hassle than buying a frame and swopping eveything out. Good luck - and post a piccie or two!
andy120t

CB650 project
CB400F frame - just missing a few bits...
ZX6R
GSXR 7/11
Triumph 5TA
CB900FZ

Offline Mvward9

  • Newbie
  • Posts: 3
    • View Profile
Re: Cb650c parts onto a cb550
« Reply #4 on: September 28, 2015, 07:42:45 PM »
Thank you very much for your help, it's much appreciated.
Point taken regarding working with what I have but my thinking is along the lines of me being a complete novice in bike building so I'm thinking if I can get a seperate frame sprayed and ready to go it'll be easier for me to work on one section at a time, restore or replace and remember where everything goes. I know it's a bit of a different method but I'm hoping it'll be fun.
I'll post some pictures as I go.
Thank you.