Topic: 1977 cb750k (K7). Which parts will interchange? Where to get parts? Cafe seat?

[bennecc]

A few months back I bought a cb750 k7.  I bought it on a whim and at the time didn't know a think about the differences between model years and K vs. F models.  I've since gathered that the 77-78 K models must have a number of differences, since it seems like it is harder to find parts. 

Can someone tell me if an earlier model oil tank (with the chrome cap) will fit on this bike?  I see some people on here trying to hide the oil tanks, but I think those early ones look nice!

Does anyone know if there is a cafe seat available that works with the stock seat mounts/hinges?  I'd like to be able to just slap on my stock seat for 2 up riding. 

There are several parts that I know I will need that I haven't been able to find yet.  Does anyone know where I can find rebuild kits for the single front brake caliper and the stock round master cylinder?

I'm sure there is some pertinent info on the boards already, so if someone out there knows of a thread I should read, feel free to just link me to it.  I tried a few search terms but kept getting 150 pages of results.  Thanks for the help!

[cobrajunkie]

Subscribing.  I have a 76 F1 and wanting to change out the side covers (and tank if need be) to pre 76 style as I simply like the look better.   Anyone know what's involved in the swap?  

I just ordered a custom cafe seat from Eric Tran @ HondaClassic31.  He makes seats that have original seat mounting points. I haven't received the item yet but it will look like this one with addition of pleats.   I wanted original mounting points and a small storage space under the seat.

You can find rebuild kits for the brake stuff at CB750 Supply.com

Happy Holidays

[bennecc]

Thanks for the info for HondaClassic31.  There is one seat on there that says it is for a '79 cb750k, does anyone know if that year has the same stock seat mounting points as a k7?

The master cylinder rebuild kits and the caliper rebuild kits for sale on cb750supply do not seem to fit the k7 model.  Maybe there is no reproduction kits for these parts???  If that's the case I'll have to see about going through Honda or just replacing the caliper and master cylinder altogether. 

[Stev-o]

There is one seat on there that says it is for a '79 cb750k, does anyone know if that year has the same stock seat mounting points as a k7?

I would bet against it, it is the first year of the DOHC.

[medic09]

77-78 are largely (not entirely) interchangeable on mechanical parts.  Cosmetic parts have obvious differences between the K and F models. Brakes will be different, but folks have adapted them.  Earlier bikes were more similar to each other; with some significant differences from the 77 transition.  Many (most?) parts are not easily interchangeable.  I don't know off hand; but a good search of the forums should bring up just about any info you want in this regard.

'78 was the last year of the SOHC.  Anything after that is likely to be very different and not fit on your bike without adaptation, if at all.

Popular places for parts include right here, eBay, David Silver Spares.  There are other places.

[HondaMan]

The master cylinder and front brake rebuild kits are available at Z1 Enterprises. For the most part, the master cylinder internal parts are all the same, except the piston is slightly shorter on the K7/8 units with the built-on brake switch: the seals are the same, so you can usually just re-use the old pistonwith the new seals. The earlier cylinders have an extra cup valve in them that would get discarded if you got the "wrong" kit, no big loss.

The front "rebuild" consists of replacing the square-cut O-ring, which Honda still offers. There are no other seals in those calipers.

The seat is another story: I ust finished a cafe' K8 with Benjie parts, which required removal of the stock pivot brackets and some fabrication of a rear seat mount, to install their cafe' seat. There's no going back!   

[damagedduck]

the oil tank will require some bracket mods,if your going to run with out a cover thats much better 1 less bracket to make,the oil lines will interchange,i did that swap in faz # 2 of my wife build,then went a total differant route,from what can remember i cut the stock 77 brackets off & make new ones to mount it lower.it looked alot better as far as i can remember,if you need an older type tank i got an extra one=chuck

[bennecc]

Thanks for all the replies!  I found the master cylinder rebuild kit at Z1, thanks for the tip.  As for the seat I think I may have found one on ebay which will work with the stock hinges.

Chuck, when you switched out that oil tank what did you do for a left side cover?  I'd like to have that early oil tank with no side cover but the k7 left side cover will look out of place.

[BrianAdair]

I have a K7 that I am currently building, I bought a rebuild kit for the master cylinder off of  http://www.servicehonda.com/look-up-parts/03
I don't know why, but my master cylinder does not have the brake switch built in, it is still on the lower triple tree, but the piston is a tad bit shorter, as HondaMan says, you can reuse the piston, I didn't know this until after I ordered a kit for K7, and it was about $20 more than a 71-76 kit.

As for the oil tank, I wanted to do the same thing, and had an older oil tank, it will hit the bracket that bolts to the outside of the frame for the rear engine bolt. So I just made a whole new tank that looks like the old style that fits in the frame.
You can see my build thread link is in my signature.


As for the caliper, the piston is no longer available, unless some one is machining them for the K7, I'm not sure if the diameter is the same as a K6 back or not. Mine only needed the square O-ring and I bought it at the same place.

 

[bennecc]

Hey Brian,
Thanks for the reply!  I haven't gotten into the caliper yet but hopefully the piston isn't all rusty.  If it is then there's always ebay.  

I love your oil tank that you built, it really makes me wish I could weld.  Do you see any way that the earlier oil tank could've been made to work, either by modifying the underside of it to clear that bracket or by having the bracket relocated or modified in some way?  I can always pay someone to do a small welding job for me, but probably not to build a whole new tank!  I really love those old style oil tanks, gotta be a way to make it work.

The seat you built is great!  If you don't mind me asking, how does the top "cover" part attach for when you are riding solo?  On a different build I built a 2-up/solo cafe seat that also houses all my electrics.  It took me forever and I still wasn't crazy about the result, but I'm not about to re-do it.  Here's some pics of it, the first one is for normal riding and the second for 2-up:





Man it was such a PITA!  That's why for this one I'm hoping to just buy one off ebay or from Carpy; individuality be dam*ed, I don't want to spend my life sanding!

[climbingaz]

Good thread....and as a K8 owner I feel your pain about the issue with parts.  Of all the hassles I've had, getting some decent side covers and carb boots were my biggest headaches.  But there's no going back now. 

[bennecc]

How about that blue frame, I think I like it!  Climbingaz, where'd you get that seat?  Just last week I boiled my carb boots in water and wintergreen oil; it worked really well!

[BrianAdair]

Hey Brian,
Thanks for the reply!  I haven't gotten into the caliper yet but hopefully the piston isn't all rusty.  If it is then there's always ebay.  

I love your oil tank that you built, it really makes me wish I could weld.  Do you see any way that the earlier oil tank could've been made to work, either by modifying the underside of it to clear that bracket or by having the bracket relocated or modified in some way?  I can always pay someone to do a small welding job for me, but probably not to build a whole new tank!  I really love those old style oil tanks, gotta be a way to make it work.

The seat you built is great!  If you don't mind me asking, how does the top "cover" part attach for when you are riding solo?  On a different build I built a 2-up/solo cafe seat that also houses all my electrics.  It took me forever and I still wasn't crazy about the result, but I'm not about to re-do it.  Here's some pics of it, the first one is for normal riding and the second for 2-up:





Man it was such a PITA!  That's why for this one I'm hoping to just buy one off ebay or from Carpy; individuality be dam*ed, I don't want to spend my life sanding!

Thanks for the compliments man!

As for the older oil tank, I didn't see a way that it could fit to where it would look good or to my liking anyway. My main reason was because my FG side cover I made wouldn't fit or clear over the tank.
The older tank is a bit larger than the K7 oil tank, and where the return oil line goes into the tank, it is on the outside of the frame right at the rear engine bracket.
the mounting tabs don't line up either, so you would have to cut and re-weld them in the right place.
It almost seemed that Honda changed the size of the triangle part of the frame where the oil tank goes for the K7 from it's previous models.


As for my seat, it's still in the air on how I want to do it, have a couple of ideas.
1, is 4 flat pan head screws that would go in the cal 2 on each side and thread into the seat pan, I'm making a metal pan that my foam and vinyl will go on, and it will bolt to the FG seat.

2, would be a tab at the back of the cal that would fit into a slot on the tail, and at the front of the cal have a key lock that would latch into the seat pan.

I'm not sure if that is a good explanation, but I will post pictures in my build thread when I get to that point.
 

[GammaFlat]

Good thread....and as a K8 owner I feel your pain about the issue with parts.  Of all the hassles I've had, getting some decent side covers and carb boots were my biggest headaches.  But there's no going back now.  

Is that a Harbor Freight front wheel chock in your picture?  Do you like it?  

[climbingaz]

How about that blue frame, I think I like it!  Climbingaz, where'd you get that seat?  Just last week I boiled my carb boots in water and wintergreen oil; it worked really well!

Hey Bennecc,  the seat is from BCR.  Was pretty pricey at $425, but I'm very happy with the finished product.  Looks good, fits perfect with the frame and stock tank, although it's about as comfortable as a 2x4  .  And I also did the 'ol wintergreen trick on my carb boots and it did work, but I'm still on the hunt for some new OEMs.   

[climbingaz]

Good thread....and as a K8 owner I feel your pain about the issue with parts.  Of all the hassles I've had, getting some decent side covers and carb boots were my biggest headaches.  But there's no going back now.  

Is that a Harbor Freight front wheel chock in your picture?  Do you like it?  

Yes Gamma, it's the cheapo Harbor Freight.  If I was using it every other day I'd probably spring for a better one, but it's perfectly fine for occasional use.  And they are always on sale.