Topic: Fork tubes diameter for CB550 + additional gastank question!

[lassenc]

Hi!

I'm about to do a dual disc conversion on my CB550K3

Are the fork tubes on earlier models of the same size, cause this lowerleg has got to be from an earlier year.

EDIT:

As I am looking for an extra gastank and sidecovers, I found this gastank at eBay!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=8044498543&ssPageName=STRK:MEWA:IT

Would it fit?

[csendker]

Don't know about the size, but they're different part numbers.  Ex:

1975:
PIPE, FR. FORK
51410-374-003

1978:
PIPE, FR. FORK
51410-404-003

And the exploded view shows some differences in the associated parts.

[lassenc]

I've only got exploded views for my CB550K3, where can I find for the other model?

[mgilvary]

I'm pretty sure the lower tubes on the earlier years are not the same as the later years. I don't know the specifics, but I ran through a couple pairs of used forks in a prolonged attempt to replace the bent forks on my 75 550K, and one of the other sets I got, which came off a 78 I believe, were different. The lower tubes were about an inch longer (although the overall length of the fork assemby was the same).

[lassenc]

Oh, okay, what about the other parts, will they interchange?

Cause I would be able to find anoter Left lowerleg and use on the right side or what?

[csendker]

Exploded views of almost any early honda:

http://www.crotchrocket.com/fiche_select.asp

There's a print option, I printed to Adobe & saved a copy including all of the parts numbers for myself for the bikes I own.  Or open two windows and do a side-by-side comparison.

[lassenc]

I can see that they are not alike

Would it work if I found a left lowerleg and used on the right side?

[bryanj]

If you have 550 K3 forks you have all the fittings on the fork slider you need If you havent they are 500 forks. If you have 500 forks best way is to get a pair of forks cmplete from any 550 as they all have the fittings on both sliders

[lassenc]

If you have 550 K3 forks you have all the fittings on the fork slider you need If you havent they are 500 forks. If you have 500 forks best way is to get a pair of forks cmplete from any 550 as they all have the fittings on both sliders

I do have all the fittings for another caliper already?

http://stalkerzone.dk/upload/igen20303.jpg

http://stalkerzone.dk/upload/igen20220.jpg

I guess I have CB550K3 forks

[Ted Nomura]

If you have 550 K3 forks you have all the fittings on the fork slider you need If you havent they are 500 forks. If you have 500 forks best way is to get a pair of forks cmplete from any 550 as they all have the fittings on both sliders

You're right. Early CB500 Fours did not have mounts for the second disc unit but there were special dual disc kit with new and stronger fork lowers.

[bill440cars]

     Hey Iassenc, I didn't see where your question of tube size was answered. The cb500,550,650 &
  750 Sohc models have 35mm tubes. There are others that have thatsize also but, I figured this is the main info you needed. You can find that info and the triple tree stem sizes also.  Later on, Bill

[lassenc]

Well, the reason I wanted the answer was if the dual disc setup that I had found would fit my bike.

But as it turns out, I don't need another lowerleg, the one I have now is already made for having another discbrake.

[beachpeople]

So if I'm following things correctly here, one can take a stock CB550 ('76) and add a stock second disk and stock caliper, toss in a dual MC, and off you go? I guess one would need longer bolts for mounting the second disk. Is there a kit out there somewhere with hardware for this sort of conversion? I have an extra disk at present, and I'm fixing to build me up a new front wheel. Just waiting for spokes to arrive.

(I was just going to be content watching this thread and let my Ebay beast take a rest. Damn it!)

[jsaab2748]

Guys, if you're looking to do a dual disc setup on a (k0-k2) 550, look on the inner side of the lower fork case to see if it's stamped with number 341. If it is, it's the same as a later model 750 k case, which allows for the use of a larger750 caliper and larger 750 rotor (which will fit because the front wheel from a 550 is the same as the 750. I do know that you can't mix parts (I.E. 750 caliper, 550 rotor etc). I'd think (though I havent tried it) that even a 750 dual disc conversion would be possible on the 550, but only if the spacing betwiin the fork legs allowed it, and again, if the fork cases were 341's. The 750 disc setup is heavier though, so the smaller 550 calipers/rotors might be a better choice. On my 550, I'm just going to "upgrade" to the single 750 setup. It looks to be a direct bolt on. If someone has experience with this please elaborate/disprove/comment. Please note that I am NOT aware whether or not this will work on F models. Hope I haven't hijacked the thread too much, and thanks. jim

[lassenc]

So I guess my K3 is ready for dual discs? Sounds nice!

Is it possible to keep the original mastercylinder, and make a T-piece to go out to each caliper?

[bill440cars]

                Everything I've read on this says that you need a master cylinder from a bike with dual discs
         because it will have more fluid capacity to handle 2 calipers. I was thinking that there was an
         article previously done on this site but, I don't remember where it is right off.
                                                Later on, Bill

[csendker]

Check the brake FAQ -->>  http://www.sohc4.us/forums/index.php?topic=259.0

[dusterdude]

So I guess my K3 is ready for dual discs? Sounds nice!

Is it possible to keep the original mastercylinder, and make a T-piece to go out to each caliper?

you could but you may find that you need more hand pressure to move the fluid since a dual system requires a larger bore mc.it just depends on if you like the pressure required on the brake lever.