Topic: Need help with front fork parts id 76 / 77 cb 750

[Toxic]

My front forks are a combination so I'm trying to id what I've got. This is for a 76/77 cb750k

From my searching I was able to determine k0 to k6 upper fork tubes are 23"
Is the upper tube on a 77 longer?

What are the spring lengths for each?

Lots of topics generated on fork length but I couldn't find these specific answers.

I need to make sure I've a matching set of components.

Right now something is off because as you can see from the pic Shaun's lower brake hose is stretched too tight.  There is very little sag on under the weight of the bike and the forks are difficult to compress under my body weight.  Pushing down on them hardly budges them.  I know I have the right qty and weight of fork oil.  The top of the forks are sitting flush with the upper triple tree.

so something is wrong.



Your help in sorting this out would be appreciated.

This site does list separate part #'s for the tubes and spring but it is not always a definitive answer.
http://www.cmsnl.com/honda-cb750k6-four-canada_model14381/partslist/F07.html

[bryanj]

judging by the amount of tube above the gaiters i think you have overstoke length tubes in there

[Toxic]

They got squashed while I was pumping the forks to get the fork oil out.

Here are a couple of wider angled shots. In these photos the forks are fully extended as the oil is out, the front wheel is off the ground and the fork caps are off.

I know the tubes came off of a 77 and that 77 was stock.

[Kong]

I think the number you want to ask for is the measurement from axle center to tube cap with the front wheel off the ground.  Lots of guys can go out to their bikes with a measuring tape and get that number for you to compare to your own; next to no-one is going to have the tube or spring length written down anywhere.  Unfortunately I have two 550s, not 750s, and one of them with an extended front end, or I'd go out and measure it for you right now myself.

[Toxic]

you're right that measurement would help.

Maybe someone has there forks apart on a bench, ya longshot, I know.

[Toxic]

My overall length is 29 3/4 " from the center of the axle to the top of the tube. Not including the cap on the top as that would add a good 1/4"

And that is with the front wheel off the ground and the suspension fully extended

[bryanj]

Thay still look way long to me, the gap between fender and lower tree looks huge

[754]

77/78 F or K fork tubes are hard-chromed all the way up.
 Aftermarket, usually have decorative chrome.. looks different and often is worn..

 The fender to tree does not look that large to me, you are at full extension.. Pop the brakeline out of the fender clip if it is that tight..

[Toxic]

The first pic showing the brake line being tight is with the forks under load.  The weight of the engine is bearing down on the suspension.  But they do look like they are extended hence the reason the brakeline looks so tight.
There is very little compression I am able to apply with my body weight pushing down on the forks.

I really need to get some measurements of the difference in tube length and spring length between a 77 and prior years.

If the tubes and springs on a 77 are longer stock that might account for the issue.

[Toxic]

I found a second set of springs and they are the same as what is in the bike 19 5/8".

I know one set came off of a 77 that I'm 99% sure was stock.  The other set are of unconfirmed origin, believed to be a 76.

so if someone happens to have there front wheel up in the air, unweighted I could really use the measurement from the center of the axle to the top of the tube.

[Elan]

i'm 95% sure that the tube size between a 76k and 78f are the same. I kave a 76k and bought 78f tubes and springs off ebay and it worked great. I did notice however that the springs seemed about a centimeter longer. I assumed that my original ones were just tired.  I can double check  when I get home.

[Toxic]

I was 95% sure fork components were interchangable between the earlier years and the 77/78 models based on my searching here.

I am at a loss to explain what the issue is.

Any assistance you can provide is helpful.

I think the solution is to pull the front end off and measure my tubes and if they are 23" just like the early years then I'm really lost.

[GammaFlat]

I am certain the lower legs between a 77/78 and 76 and prior are different.  The overall length is different.  I have not measured the tubes but I suspect they are different as well.