Topic: Can I use a 750k4 fork tube in a k2 fork case?

[ncstatecamp]

Currently on my 750k2 are a set of the 72 (early style i guess, http://www.cmsnl.com/honda-cb750k2-four-usa_model14362/partslist/F08.html#results) forks that have some pitting crap around the top end. I have a set of forks from a 74 that are in much much better condition, same length and everything but from what I can tell the internals are differnt, are these swappable or not so much? I bought an upgraded spring for my 72, and have polished the lowers on it which Id like to keep using those.

[Shane72]

Hey there,

I've got the same forks (early style) on my K2 as well, and have had many of the later ones also disassembled.  I don't believe there is any real way to do the swap you're contemplating, at least as far as I can tell.

The biggest thing that would give me pause is how the two tubes are held together in these different styles...on the early ones, there is a heavy circlip at the fork seal that must be removed to allow the tubes to separate.  The later ones are held together by the bottom bolt that is hidden by the axle.

On the early ones, that bottom bolt doesn't even need to come out to separate the legs, but, in exchange, that circlip in the seal area is a real bugger to shift.

Once the bottom bolt is out of the newer ones, the bottom tube can slide right off, no need to even remove the seal first.

You might want to consider polishing up the 74 fork legs...

All the best,

Shane

[Lost and Confused]

Hi. I currently am running 79 tubes in 74 lowers on my cb750k. Same 35mm size, 1 inch longer, different top caps. Only hard part is to figure out how much oil to use.


Bob

[754]

The 72 type has a lower bushing, no way to put that on later forks.

[ncstatecamp]

Hey there,

I've got the same forks (early style) on my K2 as well, and have had many of the later ones also disassembled.  I don't believe there is any real way to do the swap you're contemplating, at least as far as I can tell.

The biggest thing that would give me pause is how the two tubes are held together in these different styles...on the early ones, there is a heavy circlip at the fork seal that must be removed to allow the tubes to separate.  The later ones are held together by the bottom bolt that is hidden by the axle.

On the early ones, that bottom bolt doesn't even need to come out to separate the legs, but, in exchange, that circlip in the seal area is a real bugger to shift.

Once the bottom bolt is out of the newer ones, the bottom tube can slide right off, no need to even remove the seal first.

You might want to consider polishing up the 74 fork legs...

All the best,

Shane

If I did that, just polish them up, will my new stock size spring work in the newer style tube?

[Shane72]

Hey there,

I've got the same forks (early style) on my K2 as well, and have had many of the later ones also disassembled.  I don't believe there is any real way to do the swap you're contemplating, at least as far as I can tell.

The biggest thing that would give me pause is how the two tubes are held together in these different styles...on the early ones, there is a heavy circlip at the fork seal that must be removed to allow the tubes to separate.  The later ones are held together by the bottom bolt that is hidden by the axle.

On the early ones, that bottom bolt doesn't even need to come out to separate the legs, but, in exchange, that circlip in the seal area is a real bugger to shift.

Once the bottom bolt is out of the newer ones, the bottom tube can slide right off, no need to even remove the seal first.

You might want to consider polishing up the 74 fork legs...

All the best,

Shane

If I did that, just polish them up, will my new stock size spring work in the newer style tube?

Pretty sure you'll be fine with that set of springs in either year.

I just did a check on the Progressive spring replacements for both years of fork, and they share the same part number, at least for the Progressive brand replacements.

I remember replacing my springs as well a couple of years ago, and don't recall there being a distinction between spring length for early vs. later style CB750 forks.

This link will show that they fit pretty much every year--Disclaimer--this is not an exhaustive search:  http://www.oldbikebarn.com/Progressive-Suspension-Front-Fork-Spring-11-1104?sc=12&category=52219

All the best,

Shane

[ncstatecamp]

Thanks man. I guess I'll have to look into finding some seals and decide what I want to do...

[ekpent]

If your swapping the whole fork lower and all be sure that the caliper and fender etc still mounts up from a 72 to a 74. For some reason I think there may be a difference but not totally sure until I compare the two from earlier to later.

[Old Scrambler]

Good note, Ekpent.............beginning with the K3, the legs, brake mount and fender brace changed to accommodate the disk-fender.  CYCLE-X may have new tubes to fit the early legs.