Topic: Help identifying the forks

[wmajinw]

I want to replace the fork uppers and I need help in trying to identify the kind of forks that I have.

The bike is 1975 Honda CB. In accordance with http://www.sohc4.com/cb550/cb500/ it’s a K1.

CMSNL.com K1 part listing shows this kind of fork assembly -

But in reality, my forks assembly is like a K3 -

My disassembled fork pictures are below.

I found a shop locally, that lists that they sell forks for my CB500

As per the local shop sheet, my forks are 564 length, but I anxious that their share ant internals might not match.

Could anyone help me with identifying what kind of forks I have and which part number should I be looking for? If it helps, the fork lowers have "341" stamped on them.

Also, internally in the fork uppers there’s an oil lock (cmsnl link fork K3, part no. – how do I remove it? Or should it come with the new forks?

[jlh3rd]

the fork style you have showed up on the '76 750A, then the '77 550 and 750.
the "341" I would think should be the center code # for the lower fork case part #. But, CMS says the center code is "393" for the one you show....which is for the '76 750A (automatic)
However, black lower fork cases showed up on '77 750 F models...which is center code "410"...
There are people on here that can tell you if parts interchange.
CMS also shows where the same parts are shared by other models, and/or check the part in other models' parts lists and see if it's the same.

[wmajinw]

There are some fork options for CB550 but while they do seem visually identical, there's a slight difference in length.

These are identical but just a bit longer (580 instead of 564 mm) https://www.ebay.com/itm/224434760658?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Yz4P3F3cSku&sssrc=4429486&ssuid=XUg7UjtNRXq&var=&widget_ver=artemis&media=COPY

These are shorter https://www.ebay.com/itm/232217313017?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Yz4P3F3cSku&sssrc=4429486&ssuid=XUg7UjtNRXq&var=&widget_ver=artemis&media=COPY

Any ideas if there would be any fitment issues or problems them being a bit longer?

[jlh3rd]

that's where my knowledge ends. There are people on here that have mixed parts and know what can be switched, and threads on here that deal with that.


My uneducated guess, based on assuming the lower fork case is factory honda and not someone's repaint, is that the front end is from a '77 750 F. At least that gives you a starting point.
There is no telling what a previous owner/owners have mixed and matched.

[seanbarney41]

Those are NOT 77/78 750F fork lowers.  Someone has painted them black.  77/78f lowers are a much externally different casting and have very different caliper mounts.

[jlh3rd]

then the lower fork cases ARE FOR every front end that use "341" as a the center part # for the fork cases, which according  to CMS are THESE bikes
the fork style you have showed up on the '76 750A, then the '77 550 and 750.....

[bryanj]

NOT 77f, caliper mounts were different

[wmajinw]

Then the question remains, what fork uppers can I use and if theres any difference if i use slightly longer fork uppers...

I could reuse the old ones but they're quite pitted and I'm going for all polished and shiny front look.

[PeWe]

Those forks as my CB750 K6 has.
My CB750 K2 parts bike has same.
According to CMSNL introduced late K2.

[jlh3rd]

Then the question remains, what fork uppers can I use and if theres any difference if i use slightly longer fork uppers...

I could reuse the old ones but they're quite pitted and I'm going for all polished and shiny front look.

using your chart...CMS's chart....and assuming the "341" is a center part code....(where is that BTW) ( honda used showa stickers with center code #'s on the front and back shocks..theyre on my 550F.

you can use the ones for the the CB 500 Four....CB 550K....CB 550...
HOWEVER CMS specifies USA models for the KO, K1, K2, 550's using the "341" case...

[Don R]

   I have mixed and matched 341 fork parts from both 550 and 750. I bought 550 short upper tubes to shorten a set of 750A forks.
  I also built a set of "tall lower" F0/1 750 forks with shorter 550 upper tubes and 550 progressive springs also. 
 The brakes also interchange if you keep the smaller OD 550 rotors with 550 caliper and brackets and the same for 750 brakes. Some guys use the 550 brakes for 750 dual disc swaps because they are lighter.

[Deltarider]

What you need to know first, is how to identify the model of your bike. The 'year' is not meaningful. Honda did not talk 'years'. The 'year' is just an American marketing thing, the rest of the world will not know what you're talking about. Also, it helps us to help you, if we know in what country you live.
Compare the frame- and enginenumber of yours to the numbers listed in the first few pages of the various CB500 and CB550 parts lists. You only have to do this once and as a bonus you will have the socalled 'area code'. Ordering parts is then safe. Going by just the year can result in errors, as we have witnessed in this forum more than once.
Here they are: https://www.honda4fun.com/materiale/documentazione-tecnica

[jlh3rd]

well, he did say he has a K1, and it is a '75. And for U.S. bikes only, using model year after 1973 is official Honda, but even then model type is more precise.
CMS does use "year" before 1974, which is misleading, but they do include the model type, so it still gets you where you need to go.

His issue is that he does not have the stock K1 front end, so he's entered the "just what do I have?" world.
So his lower cases are "341". So he's gotta match components that fit those fork lowers.

[Deltarider]

well, he did say he has a K1, and it is a '75. And for U.S. bikes only, using model year after 1973 is official Honda, but even then model type is more precise.
CMS does use "year" before 1974, which is misleading, but they do include the model type, so it still gets you where you need to go.

His issue is that he does not have the stock K1 front end, so he's entered the "just what do I have?" world.
So his lower cases are "341". So he's gotta match components that fit those fork lowers.

I don't know where the OP lives, what country. Do you? IIRC 1973 was the last year the CB500 was marketed in the US. So... ?
This all leads to confusion. First step should always be to pinpoint what exact model you have. When others like CMSNL confuse you, turn to the original Honda parts lists and you'll know better. It's as simple as that. Only then you have a good starting point.
Personally I've been misled for decades by manuals like Haynes and Clymer and it's only been some six years, I acquired the appropiate wiring diagram for my model.

[wmajinw]

What you need to know first, is how to identify the model of your bike. The 'year' is not meaningful. Honda did not talk 'years'. The 'year' is just an American marketing thing, the rest of the world will not know what you're talking about. Also, it helps us to help you, if we know in what country you live.
Compare the frame- and enginenumber of yours to the numbers listed in the first few pages of the various CB500 and CB550 parts lists. You only have to do this once and as a bonus you will have the socalled 'area code'. Ordering parts is then safe. Going by just the year can result in errors, as we have witnessed in this forum more than once.
Here they are: https://www.honda4fun.com/materiale/documentazione-tecnica

Thanks for the information! I'm from Lithuania and the bike was bought in Netherlands/Germany I presume.

Well I went down the rabbit hole trying to find Alice, found a frankenstein.

According to my VIN (CB5002089***), the frame is a K2 (according to this https://www.honda4fun.com/dwnload/Part-List/CB500/CB500-K2-76-Parts-List.pdf)

It gives me this part number - 51410-374-003 and from the looks of it, the whole assembly is quite similar to the K3, although the part number for a K3 is 51410-404-003.

Now CMS has the 51410-374-003 forks for my model, but they're EUR 474 a piece... I'm wondering if theres any difference between the K2 and K3 forks other than the K3 are a bit longer?

The engine, on the other hand, (CB500-1026***) is just a CB500?.. (https://www.honda4fun.com/dwnload/Part-List/CB500/CB500-K1-K2-Parts-List-USA.pdf)

[Don R]

 I have used 341 forks from both 550 and 750 with various lengths of fork tube, A seller on US ebay lists tubes that are 21 13/16", 22 13/16", 22 13/16" any of them will work in 341 fork bottoms.
 They are aftermarket, mine have held up well. If your bike is a frankenbike I'd pick a length and get busy.
 I'm not sure what sellers in Europe have available, there seems to be a big sohc 4 part vendor in Germany.

[wmajinw]

I have used 341 forks from both 550 and 750 with various lengths of fork tube, A seller on US ebay lists tubes that are 21 13/16", 22 13/16", 22 13/16" any of them will work in 341 fork bottoms.
 They are aftermarket, mine have held up well. If your bike is a frankenbike I'd pick a length and get busy.
 I'm not sure what sellers in Europe have available, there seems to be a big sohc 4 part vendor in Germany.

I've seen that listing. The vendor states that the forks won't fit a CB500, but I've contacted him regarding this.

[Deltarider]

Thanks for giving further information like on your whereabouts. I already concluded you would be in Europe.
You have the same legs as on my CB500K2-ED (at CMSNL known as CB500K2 GENERAL EXPORT)*
According to CMSNL this leg fits models:
CB500K2 GENERAL EXPORT
CB550 FOUR 1975 CB550K0 USA
CB550 K1 FOUR 1975 USA
CB550 K2 FOUR 1976 USA
So far the official info.
Now, the middle number usually determines the model of the bike. However, I've learned that with the launch of the CB500/550K3 models, Honda renamed practically all parts into -404- even if some parts were identical to the same parts on previous models like ours. Although I can't give a 100% guarantee and neither can CMSNL, there is a good chance the -404- leg is exactly the same as the 51410-374-003 we have.
I don't know if this much help, but at least you now know what you've got and what your model is supposed to have. Personally I find that a good starting point.

* It's a bit tricky to arrive at the appropiate parts list at CMSNL as our model is somewhat hidden.
Here is how it works: When you open the CMSNL site: https://www.cmsnl.com/honda_model8286/
, type in the search window: CB500K2. The program will react with two options: the US K2 model and the K2 GENERAL EXPORT. Select the latter. I don't know why CMSNL choose this, maybe to express this particular European K2 batch has been 'grey import'.
But you can also consult the parts list CB500K2-ED, -F, -G at www.honda4fun.com.  https://www.honda4fun.com/dwnload/Part-List/CB500/CB500-K2-76-Parts-List.pdf

[wmajinw]

Thanks for giving further information like on your whereabouts. I already concluded you would be in Europe.
You have the same legs as on my CB500K2-ED (at CMSNL known as CB500K2 GENERAL EXPORT)*
According to CMSNL this leg fits models:
CB500K2 GENERAL EXPORT
CB550 FOUR 1975 CB550K0 USA
CB550 K1 FOUR 1975 USA
CB550 K2 FOUR 1976 USA
So far the official info.
Now, the middle number usually determines the model of the bike. However, I've learned that with the launch of the CB500/550K3 models, Honda renamed practically all parts into -404- even if some parts were identical to the same parts on previous models like ours. Although I can't give a 100% guarantee and neither can CMSNL, there is a good chance the -404- leg is exactly the same as the 51410-374-003 we have.
I don't know if this much help, but at least you now know what you've got and what your model is supposed to have. Personally I find that a good starting point.

* It's a bit tricky to arrive at the appropriate parts list at CMSNL as our model is somewhat hidden.
Here is how it works: When you open the CMSNL site: https://www.cmsnl.com/honda_model8286/
, type in the search window: CB500K2. The program will react with two options: the US K2 model and the K2 GENERAL EXPORT. Select the latter. I don't know why CMSNL choose this, maybe to express this particular European K2 batch has been 'grey import'.
But you can also consult the parts list CB500K2-ED, -F, -G at www.honda4fun.com.  https://www.honda4fun.com/dwnload/Part-List/CB500/CB500-K2-76-Parts-List.pdf

From what I see, the main difference between the K2 and K4 forks is the Comp. rod - K3 has a tapered end and K2 has a straight end. this in turn affect form of the oil lock, which goes at the bottom of the fork lower and, I guess, the fork lowers themselves, since they have to accommodate the different oil locks.

So either it's the 374 forks from Ebay (if the vendors confirms their fitment to CB500) or 404 forks from TNK some (Italian manufacturer). Considering the shipping and import costs, the difference between these 2 is immaterial.

[Kelly E]

We have used TNK fork tubes on several bikes with great results including the 74' CB 550 K0.

[wmajinw]

Thanks for all the input.

The gentleman from Ebay states, that the forks will fit any CB550 but wont fit CB500 and CB550F.

As far as I've looked, the CB550K0, K1 and K2 use 51410-374-003 (as previously stated. BUT the CB550K3 and K4 use 51410-404-003. For reference, I'm talking only about the USA models. My guess is since the gentleman is from the states and, as Deltarider correctly pointed out, the CB500K2 General Export model is quite hidden, he disregarded that those forks could be used for a certain CB500.

The gentleman also states, that the 51410-374-003 he's selling wont fork on CB550F models. From the parts list details you can see that those forks, at least the USA models, don't gave a small spring dampening rod and the fork number is totally different. The CB550F's for EU seem to have used the tried and true internals with 51410-404-003 forks.

I've opened a ticket with CMSNL to ask them their opinion if the 51410-404-003 can be used as a replacement just to be sure before biting the bullet and ordering the forks off of ebay.

[jlh3rd]

FWIW....your time, your money, your bike. And clearing up some false statements.

you do not have a cb500 K2 general export bike. You have a k2 frame, a K0 motor, with an entirely different front end. Plus, from what you've said, your front end has mismatched parts itself. You do not have the boots, the pipes are exposed , which first showed up on european Cb 500 k3. However, the k3 cases are "393", you have "341". "374" pipes fit "341" cases...."404" pipes fit "393" cases.
Removing the boots and adding K3 dust seals and other k3 parts to a k2 front end is MAYBE what was done...
Maybe....so if that is what you have:
It doesn't matter where you live, you have to figure out what pipes can fit those lower case "341", which are "374" pipes
      You already had people on here tell you from personal experience and actually swapping parts what pipes fit the "341" cases. That's what matters. Once again, your time and money. Some vendors make you pay return shipping....
I'd want to be sure....
I posted what models are fitted with "341" cases...european and U.S. ..according to CMS, which includes a cb500 k2 general export....
That should be your reference to vendors....or what some others posted on swapping, for pipes that fit those cases. For my money, that takes precedence over guessing.

Also, fyi...U.S. model year date is NOT a marketing ploy of the U.S. It was official honda policy. Period..for legitimate reasons..
facts over opinion:

[Deltarider]

[...]
Also, fyi...U.S. model year date is NOT a marketing ploy of the U.S. It was official honda policy. Period..for legitimate reasons..
facts over opinion:

That is American Honda,not the Honda we have in our official docs, which we have collected with great care to check for all the world.
I thought it wise to limit my remark to the frame which OP indicated. As you know the forks are part of the frame. I hope you don't mind, I've directed OP where he for himself can find out what is original on his bike and what not. Again, I hope you don't mind and I wish you a good day.

[wmajinw]

FWIW....your time, your money, your bike. And clearing up some false statements.

you do not have a cb500 K2 general export bike. You have a k2 frame, a K0 motor, with an entirely different front end. Plus, from what you've said, your front end has mismatched parts itself. You do not have the boots, the pipes are exposed , which first showed up on european Cb 500 k3. However, the k3 cases are "393", you have "341". "374" pipes fit "341" cases...."404" pipes fit "393" cases.
Removing the boots and adding K3 dust seals and other k3 parts to a k2 front end is MAYBE what was done...
Maybe....so if that is what you have:
It doesn't matter where you live, you have to figure out what pipes can fit those lower case "341", which are "374" pipes
      You already had people on here tell you from personal experience and actually swapping parts what pipes fit the "341" cases. That's what matters. Once again, your time and money. Some vendors make you pay return shipping....
I'd want to be sure....
I posted what models are fitted with "341" cases...european and U.S. ..according to CMS, which includes a cb500 k2 general export....
That should be your reference to vendors....or what some others posted on swapping, for pipes that fit those cases. For my money, that takes precedence over guessing.

Also, fyi...U.S. model year date is NOT a marketing ploy of the U.S. It was official honda policy. Period..for legitimate reasons..
facts over opinion:

Thank for the information. My fork did have the boots, but I didn't include them in the picture.

I've only seen the 51410-374-003 on Ebay so I suppose they're the most viable option. M

[jlh3rd]

😳...lol...well,  you posted a pic of a K3 front assembly and said that's what you have.....your pic.

quote " like a K3"..
no wonder "things" got twisted. Sure wished you'd have mentioned those boots a lot sooner....that would've helped just a little...😉