Topic: 550 lower fork tubes ?

[78 k550]

Hey All,
I saw a add up on ebay. A listing for 750 chopper lowers. He aslo advertizes they will fit a 550 also. Are they the same? I was going to put a set up and if i can add that it might help them sell.

Paul

[bryanj]

Depends on the model, some are direct swop, some with a small amount of work (or different wheel) some no way at all

[78 k550]

his on ebay are cb lowers. The ones i have are off a 72 cb500. My ? is would these fit a 750 of the same era?

Paul

[blackhog02]

my 1978 cb750 forks are about 2 inches taller than my 1977 cb550 forks.  The lowers sure look the same.  The stem on the tripple tree on the 750 is about an 1inch taller than the stem on the cb550.  Hope this helps

[bryanj]

At 72 500 and 750 are different but 450 (disc type of course) and 750 are same lowers but 450 is shorter overall-- I got a NOS pair of those somewhere

[n9viw]

This is an oddity that has struck me recently as well. I have a '73 CB750 that looks to be factory-stock. I also have two sets of over-length forks, and a set of what are supposedly stock CB550 forks on my bobbed CB550.
Of the four sets of forks, only the ones currently on the 550 are different- the lower legs are 14.5" from axle to top, and the forks are 27" overall. The lower legs on the other three- the CB750 forks, and the two sets of over-length forks, all are stamped "341" on the inside of the leg, and are only 12.5" from axle to top.
What's interesting is that one of the sets of overlength forks came on my 550 when I bought it (first pic in this album: http://pg.photos.yahoo.com/ph/n9viw/album?.dir=4eb8&.src=ph&store=&prodid=&.done=http%3a//pg.photos.yahoo.com/ph/n9viw/my_photos), but they're identical to those on my 750. The brake hardware between them is slightly different, to account for the larger disk on the 750, but the legs are the same. The other set of overlength forks also came from a CB550, but had the CB750 brake hardware on them.
I do know that the upper legs on both the 550 and 750 are 35mm, so that would make them basically interchangeable, so long as the internal piston stays with the upper legs. Apart from that, I don't know what the difference is, nor why the lower legs on the forks I currently have on the 550 (which were supposedly from a '75 550) are different from those I had on it to start.

[bryanj]

Early 750 and 450 had a wierd shaped bracket bolted to the fork leg with the swinging bit attached by a steel pin that is held at both ends in the alloy bracket, later 750 and 500 have a big steel pin that the swinging bit pivots on, with a big bolt at the bottom and a small alloy casting at the top with two 6mm bolts that also hold the fender bolts &50 front end complete and 500 front end complete will swop; discs diff diameter etc. if you get the 450 forks the steel tubes are same as 500(bout 1" shorter than 750) whilst the alloy sliders are same as early 750 (341 number)

[hondachopproject]

Hey All,
I saw a add up on ebay. A listing for 750 chopper lowers. He aslo advertizes they will fit a 550 also. Are they the same? I was going to put a set up and if i can add that it might help them sell.

Paul

Again, as said depending on year. I know this isn't what you asked, but On my 76 550 I swapped out my  shorter tubes for longer 750 tubes, Year unknown, Lowers where different and the 750 forks had a different rim than my spoked rim. I wanted to use the spoke rim, so I just swapped lowers on the tubes so...... theoretically if the years are right, diameter is right, I don't see why the lowers wouldn't fit your tubes.