Topic: My first bike: '78 CB750k

[fendersrule]

The ignition key may have to be rebuilt. It's probably the clicking mechanism inside. I tried spraying some contact cleaner and 3-in-1 oil inside the keyhole with no avail. It works fine, you just have to wiggle it a little. It's one of those things that once you get good at it, you'll not have a problem. I'd hate to rekey everything....that would suck.

Anyways, returning to the clutch cable. I found a cure if your clutch cable is slipping..

As you know, it was really the mechanism above the carbs that were causing the trouble with a "hard to pull" choke cable; they just needed a good spray of lithium grease.

Toyhuff is right: there is a "tension" thumbscrew underneath the choke knob. If you remove the rubber boot that sits underneath the choke knob (pry it gently with a screwdriver), then you will find the choke knob thumb wheel, which is suppose to tighten the prongs that "dig" into the choke shaft. The idea is once you tighten it, the prongs will dig further into the shaft (that's what she said).

Anyways, tighten it tightly with your hands (don't use a tool) and see what that does for you. If your choke knob is still performing badly (mine was still slipping), then here is a killer trick, which I have not seen anywhere yet on the interwebz, so soak this up!

1) Remove rubber boot at the base of the choke knob; pry gently with a screwdriver.

2) Unscrew the finger tensioner (plastic I think).

3) Use generic heat shrink tubbing from a soldering kit. I used black, and cut only about a 3-5mm piece off

4) Take that tubbing piece, and slit it in-half, making it look like a lock washer.

5) Take the piece and slip it onto the bottom of the shaft while the finger tensioner is all the way up.

6) Screw the finger tensioner back on, and give it a nice snug fit.

7) Test your choke knob. It should work beautifully. There shouldn't be hardly any effort needed, and it should stay anywhere you leave it.

I've gorilla tested this for about 15 minutes, with no change and it held strong. You cannot see this repair at all, especially if you have the rubber boot; it will look and work great. If it becomes a perminant fix, then I'll post it in the how-to section.

Rock!

[fendersrule]

I would buy another switch.


Here are a couple pics of my K8, look familiar? All original, 25K miles.

That's really a damn beautiful bike. There was someone around Salt Lake City selling one in this exact color for $1850 (and not a penny less), and it was not near as good condition as yours. I have the "rarer" color, but not necessarily the "better" looking color. 

You ought to be proud of that. A perfect CB for the "taller" guys. Nice looking chrome, and the paint looks great. The side covers have their original decals and emblems. You even have the seat rail and those hard-to-find headlight reflectors. That's called freaking original, and you better keep that for as long as you are alive. If you sell it, some kid is going to buy it and screw it up. Are you running 100/90/19 and 120/90/17s?

Personally, I don't like how the '77-78s gained all the "extra" stuff, kinda made them look a bit bloated. To me, I dislike the look of the seat rail, but I have tons of respect when I see one left on. They really break up the simplicity and the flow of the rear. I dislike the '78 and '77 styling of the side cover emblems and the decals. The black model was only a "decent" color to me, but the red one (such as mine) is weird. Maroon, gold, and blue? The seat design was "ok," but the '77 seat produced a much more "classic" CB look, and I'm fairly sure it supports taller riders better. Everything else I absolutely love about the 77-78s.

I think you'll really enjoy this thread Stev-o. Hope to keep getting your replies. I'm turning my '78 back into "mostly" OEM form, while doing some retro stocker touches to it.

The funny thing is-- After I mount the '77 seat, this bike won't be a '78 anymore. It will be a '77, excluding the VIN.

[Stev-o]

Thought you might like to see the pics. I like all of my bikes but for different reasons. This one is in such remarkable original cond that I would never consider modifying it. Those are new Dunlop 404's on it, 130/90-17 on the rear.  I bought the bike from a guy in N. Mexico, I believe the dry climate was the main reason that it is relatively rust free. It runs fantasic and I really enjoy it in the hills around here.  The only thing I don't like is how quiet the stock exhaust is, but it will remain on there as long as I have it. And have no plans to sell it anytime soon.

[fendersrule]

I love how the exhaust sounds on this bike. Makes the bike sound so classic and good with some meat to it. My dad with his '79 would kill for our exhausts. He's got some crappy cut-off 4-into-2 exhaust because the PO just had to throw on saddlebags. Don't like the sound of it at all.

[fendersrule]

Steve-o, did you try my trick?

[Stev-o]

Steve-o, did you try my trick?

No, not yet. My K8 is currently being stored offsite, have my K4 and 550 cafe in the garage. My wife freaks if I have more than two bikes at home so I rotate. 

[madmtnmotors]

Is this the "Show off your K8" thread?

[Stev-o]

Hey Wilbur - actually it's show the newbie your sweet K8!   And you should should direct him to some of your awesome Godzilla rides you 've been on!

[fendersrule]

Wilbur, do you also have a red K8? It's hard to tell by the picture.

It seems that we have such a rare color. You almost always see them in black.

You K8 purists are going to hate me so much over the following weeks. In one week , the only thing that will be "K8" about my bike will be the frame VIN.

I added the clip that goes under the gas tank lock. It's nice and firm now! Easy fix, and that's all I was able to do tonight.

My tires also arrived, along with my DID ORing chain.

[fendersrule]

I think I'm going to go with '78 Super Sport emblems. I like the font styling more than the k styling.

Are we sure that the latch studs on the seat are indeed studs? I just broke the other-side. I had the bright idea of tightening two washers together on the same stud, and then loosening. After awhile, it broke.

It seems to not be listed in the schematic. I'd like to get the studs ready because the seat that is arriving will need them all replaced. I hope I'm not going to have to remove the seat in order to replace them, but it's possibly looking that way because they are not acting like studs.

[madmtnmotors]

fenders,
    Mine is black with the gold stripes, the lighting and angle made it hard to tell.




Currently sporting a 78'F motor (sshhh...) with some chrome bits. The original engine will get built up and reunited.

As for the mounting "studs" I think they are a bolt welded in from the top of the pan. I've got an old pan I can verify later. In a similar situation I have considered drilling the center and tapping the hole (through the bolt head on the backside) for an actual stud and securing with red loctite. You could drill and tap for the same diameter. This would let you leave the seat cover intact.

[fendersrule]

Thanks Wilbur for the info. I wouldn't mind if you confirmed that with your old seat pan, but I think you're right. These things are not acting like studs, they are acting like fixed bolts.

I like your idea of drilling and tapping. I think that's going to be my plan.

I see you have a black '78! Looks like a good highway cruiser! I think that's helping to confirm my thinking that the red is a rarer color. The windshield looks sleek! Glad the bike isn't butchered when you installed it like mine was.

[toytuff]

Steve-o, did you try my trick?

No, not yet. My K8 is currently being stored offsite, have my K4 and 550 cafe in the garage. My wife freaks if I have more than two bikes at home so I rotate.

That is just plain sad. 

tt

[madmtnmotors]

Okay, looked at the spare seat pan and it ain't pretty. They do appear to be bolt-like but the head on the backside of the pan is flat and VERY thin (less than 1/8" thick) and I'm not sure how well this would support a stud since there's not much material to tap. Another option might be a threaded rivet nut or rivet stud: http://www.rivetsinstock.com/rivet-nuts-threaded-inserts/blind-threaded-studs.html

[fendersrule]

Thanks for checking on that. I may just take it to a reupholstery shop and have then do it after I clean and powdercoat the pan.

Cylinders are reading 115-120 PSI consistently, cold.

[fendersrule]

Just some videos of it in action before the teardown.

A gentle cruise:

1978 Honda CB750

Getting on it:

MVI 0884

After removing the chain, found that it didn't have a master link. The chain was simply removed by pressing one of the links out.
 

[fendersrule]

This Harbor Freight stand was such an amazing value that my father bought one as well:




My work area:


My parts cleaning "station":


Painting the sprocket cover:


Mounted, and cleaned:


Honda replaced the bearings in my rear hub/wheel. They were frozen. The axle was also frozen in place as well, and had to be removed. They recommended that I leave the front bearings alone because they're fine. I've got some more cleaning to do to the hubs, but here's the new tires that were mounted. They replaced the wheel liners, and installed new tubes in both:


Replaced the generic bolts there were holding my headlight on with the real thangs:

[fendersrule]

Vinegar soaking:







Cleaned the $hit out of this axle, which was frozen before. Now all the spacers move freely on it. Got some "racing" waterproof grease. I'll try to find a diagram on how it all goes back together because I totally forgot:



Polishing the drum hub:





It may or may not be that well seen, but at least it's shiny.

[fendersrule]

Hagon shocks:



Airbox came in. Not going to fuss with it for awhile, but I'm glad I have one now:


The guy on Craigslist also had a freshly powder coated chain guard. Wow!





I'd say I did good replacing that, wouldn't you guys?

These babies came in:




Now I gotta figure out how to do a headlight ear transplant. That "speaker' looking thing on the fork ear has gotten 3 mechanical engineers confused. What the hell is that thing!

[Stev-o]

Hey Fenders,

You've been busy, all looks good. I like the Hagons, am considering them for my 550. Try some Mother's Back to Black on the air box.  Nice find on the chain guard. The "speaker looking thing" is the turn signal on device, Didn't think the K7 had one.

http://www.westernhonda.com/fiche_section_detail.asp

[madmtnmotors]

That "speaker' looking thing on the fork ear has gotten 3 mechanical engineers confused. What the hell is that thing!

That's the sonic warp modulator! Don't knock it out of whack! 

[fendersrule]

What do you guys think? Got some simple wiring to do, but she's about done!

[fendersrule]

New front brake pads installed. All greased up. Torqued to specs.

I need to figure out what the hell is going on with my turn signal wiring. Left blinkers work (front and rear), but you have to get it in the right position. Too Far left throws off a steady buzzer, while losing the signal to the lights. Far right throws off the same steady buzzer. I've yet to see any of my right turn signals work, front or rear.

Both front running lights work in the turn signals.

Going to have to get this figured out. Diagram is going to be needed.

Aside while doing that, I'm hoping to have my rear axle, brake, tire on in the next few days. Gotta install the shoes and re-grease everything. Got some cool synthetic waterproof grease at honda for this job. That axle is never gonna freeze again.

[Stev-o]

Here ya go...


http://data.sohc4.net/WD750/CB750_K3-K7_WD.jpg

[Tripps]

Nice bike. My first bike was also a 78 CB750K, also maroon, also 11,00 miles.