Help with fork lowers identification please

[Nashfly]

Hi,

I have a completed project based on a US import CB500 Four (1972)

The fork lowers are slightly longer than standard - top to bottom 357mm (just over14 inches)

There's no markings on them, they are 35mm and work just fine

Can anyone throw some light on what the part numbers are or what model they are from?

Alternatively, can some let me know the length of a standard 1972 CB500 Four fork lowers.

Thanks in advance for any assistance

Pics below

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[deltarider]

I bet there's a three digit number on the inner side. 341?

[3scs]

Like this

[Nashfly]

I bet there's a three digit number on the inner side. 341?

Thanks for the reply, but I have checked both lowers and there are no markings

[Nashfly]

Like this

Thanks, as above there are no markings, is the one in the picture measuable? If so, could you please let me know?

By way of explanation,  I'm looking to upgrade the front brake, probably to an AP Lockheed set up, which will require a bit of machining to the fork lowers

[McCabe-Thiele (Ted)]

My 500 front forks are 12" from the center of the front spindle to the top of the ally .

[3scs]

The forks on both my 550 f2 and K3 are both around 14 inch

[3scs]

Forget the above just taken the dust cover off they’re 354mm

[Grewth]

Fork sliders would appear to be the later type off the CB550F or even the CB750F1 or K7.
If you're not aiming for a 100% standard bike, I'd stick with them as they are actually better forks than the early type.
Might be worth checking the overall length from the top of the tube to the axle centre and comparing it with the original type fork

[Oddjob]

Look to be off a 550 as the 500 didn’t get the extra caliper mount on the right hand fork slider that yours clearly has. Most likely 550f1 as the f2 had longer sliders iirc.

[Nashfly]

Look to be off a 550 as the 500 didn’t get the extra caliper mount on the right hand fork slider that yours clearly has. Most likely 550f1 as the f2 had longer sliders iirc.

Fork sliders would appear to be the later type off the CB550F or even the CB750F1 or K7.
If you're not aiming for a 100% standard bike, I'd stick with them as they are actually better forks than the early type.
Might be worth checking the overall length from the top of the tube to the axle centre and comparing it with the original type fork

Massive THANKS to all who have responded - very helpful

By way of explanation, the fork leg in the image is actually a LH one, the RH one is on the left, so that the standard Honda caliper sits behind the forks (pic below)

When I purchased the project, the LH fork leg had been machined (bodged) to take a mounting bracket and a caliper & master cylinder from a childs minimoto fitted (no, I'm not joking!)

Whilst the machining damaged the brake mounts, the strength of the fork lower was not affected. With it being fitted on the right side, it's not even visible

With the standard caliper the braking is adequate, helped by a fair bit of weight reduction from standard (pic below)
So I was thinking of fitting an AP Racing set up - I already have one on my K4 race bike

I ordered a new LH fork leg for a CB500 Four and found it too short (the ebay seller allowed a return and refund) hence the reason for my original post to ascertain which leg it might be

The assistance from all of you, has led me to either try to get a LH leg to match, or go for the CB750 option as a pair

Reference was made to "keeping it standard" whilst I for many on here that is important, and I get that. However, at 71 years old I'm still into my race bikes........

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Thanks to you all, this is a great forum

[Johnny4428]

When I purchased the project, the LH fork leg had been machined (bodged) to take a mounting bracket and a caliper & master cylinder from a childs minimoto fitted (no, I'm not joking!)

Just, why would you? On such a grand machine! 😳