Fork tube length quiz.

[Flandango]

Hey guys and dolls,

Nice to meet you all. I have just bought my first CB750 and I am starting a Cafe Racer build. I'm reasonably handy at mechanics and metalwork but there are some questions you can't find the answer to in the tool box.

I have a '74 CB750 K4. I bought a new set of fork tubes for it as the old ones are badly pitted and one of them resembles a chrome and brown banana (delicious!). I stripped the forks yesterday only to discover that the fork legs are not from a K4 but seem to be from a later model bike. I have a manual that cover all models 69 - 79 and the forks that are on my bike appear to be the same as the ones in the exploded diagram for the CB750 F which, according to the manual (Haynes), was introduced in 1975. Sounds straightforward right? Well, here's the kicker:

There are a set of fork tubes (or stanchions as they are called over here) for sale on ebay.co.uk for "Honda CB 750 F (SOHC) 76-78". They sound like the perfect fix but the seller has just informed me that they are of length 607mm. The length of the tubes on my bike is 580mm. This is a killer because now I know that the forks on my bike are not from a 750K and not from a 750F but I don't know what they ARE from and I need to know so I can replace them!

Does anybody know what model of CB750 (if any!!) has fork tubes of length 580mm and OD 35mm. They appear to be identical to this set up http://images.cmsnl.com/img/partslists/honda-cb750k-750-four-k-1978-usa-front-fork_bighu0057f5707_c503.gif which is the Haynes manual diagram for the forks of CB750 F.

I would really appreciate any insight into this as I am bouncing my head off a brick wall here and I want to get this bike built!!

Thanks.

 

[dirtdigger]

Send some actual photos. Maybe some use forks off of a cb500 or 500

 

[Flandango]

Ok dirtdigger, I'll sort some photos shortly.

 

[Flandango]

It will have to be in the morning as I'm at work.

 

[Flandango]

Also I haven't yet made enough posts to be allowed to post pictures.

 

[Flandango]

Well actually now I have so standby for photos of the dismantled fork leg.....

 

[Flandango]

 

[Flandango]

Can you guys tell me what model CB750 these forks are off? They are currently on my 1974 CB750 K4 but I suspect they are not the originals.

 

[dirtdigger]

They rally look like the F forks. You said the seller gave you a measurement that is different from yours....are you sure he is measuring it the same way, same spot etc as what you are measuring?

 

[Flandango]

Hey dirtdigger, Ya he told me to make sure my fork tubes were 607mm in length before he posted them. They are only 580mm so he cancelled the order and refunded me the price of them. I measured the naked tube from end to end without the top nut in. I assumed he did the same as the new tubes do not come with top nuts but now that you mention it I must ask him. They appear to be identical to the exploded diagram for the F forks. Any idea of the official length of the F fork tubes and where I might get a new pair?

 

[Flandango]

It has been suggested to me that there may be two variants of the CB750 F forks with different lengths but the same internals. Can anyone verify this?