Topic: "I will git 'er done, eventually" 750K8 project

[Marks78]

A few photos to get started,(till photobucket f#@$*d it). Not in the best of shape but hey it starts and runs! Just don't try to ride it    No working front brake, throttle cables so stiff once you managed to turn it a bit it wouldn't even think about snapping back on it's own. Bald, almost 40yr old front tire, F model side covers, etc... but it did include some extras that made it all worthwhile  two vetter fairings with matching (for one of them) lowers and correct mounting bracket, one spare front tire (only 7yr old) and a trunk that might make a good parts bin and one very clunky old hard-frame mount for unknown brand of side bags.   
 
as it is today, waiting for fork rebuild and new steering head bearings
Blade style fuse box being retrofitted and one of many new electrical connectors

slight clearance issue between the shock and chain guard (not yet sure of the best solution here)

and the ancient, possibly original front tire

If anyone knows how to decipher this code I would love to know what it tells about the age of the tire

Thanks for looking and wish me luck!  I will post updates as progress is made but it will be one of those slow to go projects.

[SOHC4 Cafe Racer Fan]

Definitely in need of new rubber. 

I would perform the 3000 mile service items and get it running safe and reliable before you engage in alterations.  That looks like the direction you're taking. 

What's the overall plan? Run and enjoy, restore, modify?

[Desert-SOHC]

Those brackets are for Vetter bags and I want them if your gunna get rid of them!!

Nice start.

Your chain guard is probably bent...check and see if the chain is centered.

[Stev-o]

Good pics, Mark!   The tire date of manufacture code is typically 4 digits [week and year] but your tire is O-L-D!  Suggest Avon, Bridgestone, Dunlop or IRC.

I may have some nice throttle cables for sale...[sold my K7 before installing]

[Marks78]

Definitely in need of new rubber. 

I would perform the 3000 mile service items and get it running safe and reliable before you engage in alterations.  That looks like the direction you're taking. 

What's the overall plan? Run and enjoy, restore, modify?

It definitely needs a thorough going over before being ridden! The wiring connectors would literally turn to powder when touched! 
Can't decide on the tread pattern I want--vintage/old school or more modern street bike but I need to figure it out soon cause I won't even test ride around the back pasture with those tires! For now I want to clean it up as much as I can and ride and enjoy this summer. It sat out under an Oak tree for about 20yrs according to the PO (the air-box was FULL of acorns) so it really needs to be stripped down to the frame and cleaned from top to bottom to do it right. That just sounds like too much work for me right now. Though I do plan on painting it soon. Don't want it to be too ugly. 

[Restoration Fan]

Nice find.  I have a set of Pirelli's on my 750K8 and I really like them a lot.  Good grip in both dry and semi-wet conditions.  I have no idea about how they handle wet conditions because I haven't taken that bike out in wet conditions/rain.

[Marks78]

Those brackets are for Vetter bags and I want them if your gunna get rid of them!!

Nice start.

Your chain guard is probably bent...check and see if the chain is centered.

PM sent concerning bracket.   I will surely check the guard to see if it's bent. The chain and sprockets look original so they are definitely getting replaced! 

[Marks78]

Good pics, Mark!   The tire date of manufacture code is typically 4 digits [week and year] but your tire is O-L-D!  Suggest Avon, Bridgestone, Dunlop or IRC.

I may have some nice throttle cables for sale...[sold my K7 before installing]

Thanks Stev-o, truly appreciate the help with posting pics and the suggestions for tires. Would really like to have matching tread front & rear but haven't found a set like that yet.
PS--Thanks for the offer on the cables. I lubed them really well and they seem to be ok for now, at least till I get it back on the road. But I will send you a PM and take them off your hands so I have a good set for when I am ready for them.

[Stev-o]

It can be hard picking tires especially if you have the stock 17" rear wheel. 
I put Dunlop 404's on my K8....

[Desert-SOHC]

The chain and sprockets look original so they are definitely getting replaced!

Do a 530 conversion on the chain, there are tons of different size sprockets available to fine tune your ratio, and it SO MUCH lighter than the 630 that they came with and the new 530 chains are plenty strong for these old bikes

[Marks78]

The chain and sprockets look original so they are definitely getting replaced!

Do a 530 conversion on the chain, there are tons of different size sprockets available to fine tune your ratio, and it SO MUCH lighter than the 630 that they came with and the new 530 chains are plenty strong for these old bikes

I have read about that conversion and I am interested in researching it some more. Other than the weight savings and availability I'm not sure what the advantages would be. I am definitely not an aggressive sport-rider, mostly like to cruise the highways (two lane black-tops) so don't know if I would notice many advantages or not. Definitely will look into it further though. Thanks for the suggestion!

[Desert-SOHC]

The chain and sprockets look original so they are definitely getting replaced!

Do a 530 conversion on the chain, there are tons of different size sprockets available to fine tune your ratio, and it SO MUCH lighter than the 630 that they came with and the new 530 chains are plenty strong for these old bikes

I have read about that conversion and I am interested in researching it some more. Other than the weight savings and availability I'm not sure what the advantages would be. I am definitely not an aggressive sport-rider, mostly like to cruise the highways (two lane black-tops) so don't know if I would notice many advantages or not. Definitely will look into it further though. Thanks for the suggestion!

I did it to get lower rpm's at highway speed for better mpg and smoothness.  They'll do 6K all day long, but I don't like the buzz in the mirrors up there, 4,500 is much smoother.  That's why I went to a 530, I have to do 80+ mph on the highway or get run over around here, and couldn't find the sprockets to do that for a 630 chain, but could do it in a 530 conversion.

[Marks78]

It is time to decide--Do I rebuild the Tach and Speedometer or do I replace them? They are not in terrible shape, the speedo has a worse dent in the black metal part of the housing than the Tach in the photo and they definitely need to be painted and polished! I've watched the 'how to disassemble' videos and feel like I can do the deed but I can't decide if doing it just for the experience would be worth it or if I should just buy replacement gauges and spend my time doing other repairs. It appears as though I could spend as much on parts as I would on replacements.  Also, the chrome portion of the Tach is slightly out of round in the bottom left portion, don't know how tricky that will be to fix. Anyone taken them apart and rebuilt them successfully? What do you think? (the black spot on the gauge face is a dead spider  )

[Desert-SOHC]

All that stuff is available new from CB750faces.com if you want to do it, or you can ship them off and they will rebuild them for you.  I picked up another set  for cheap and tested them on Mable, they will be rebuilt and will replace the ones on her now and I will sell the ones I'm using.   

[Marks78]

Thanks for the input Chuck. Took the Tach apart over the weekend and decided to order new face plates for the gauges and see how they turn out after lots of cleaning and a new coat of paint. Pretty easy to disassemble. Curious to see how easy it is to re-crimp the ring for reassembly. 

[Desert-SOHC]

Thanks for the input Chuck. Took the Tach apart over the weekend and decided to order new face plates for the gauges and see how they turn out after lots of cleaning and a new coat of paint. Pretty easy to disassemble. Curious to see how easy it is to re-crimp the ring for reassembly.

New rings are available and there is a video on youtube about it from what I gather...I havent got there yet.

[Marks78]

I stumbled across a set of gauges for a "to good to pass up" price so, for better or worse, I ordered them instead of refurbishing mine. At $45 each I couldn't say no. 
Fork seals, fork cap o-rings, carb clamp and breather box gasket should be here in a few days. 

[Marks78]

A little update with a big question. I took the forks apart today and cleaned them up in preparation for installing new seals and oil and found something that has me stumped. First off I was not aware that the tubes have a long (non removable) metal sleeve in them, one of the metal sleeves is perfectly smooth inside - no problem there - the sleeve in the other tube has what looks like a welded seam running the entire length of the sleeve  . This seam is rough enough that it has worn several grooves in the sealing ring of the damper rod.  So...my question is, do I need to replace the tubes or does someone know of a way to smooth out the rough seam?!? All help is much appreciated!

[Marks78]

Decided to try my hand at re-spokeing a wheel so I ordered spokes from "4into1" and wrenches off Amazon. Spokes have arrived and wrenches are on the way. Had/chose to cut the front tire off as it was older and stiffer than I am and I didn't feel like fighting it.  Anxious to find out if I can figure this out without screwing it up!   Haven't found any info concerning the funky seam in the fork tube so it will get replaced. Found a set from CycleX for a good price. Springs are at their wear/sag limit so they are getting replaced as are the wheel bearings. Slow but steady progress is better than no progress, right?!?

[Desert-SOHC]

Brave guy....I haven't tried that yet, but its coming.

[Marks78]

Maybe just a glutton for punishment?!    I'll find out over the next couple of weeks and, for better or worse, post the results.    Any thoughts on whether or not a steering bearing race driver is helpful? Like this one,  http://www.vintagecb750.com/parts/480/35-9124.jpg

[Stev-o]

   Any thoughts on whether or not a steering bearing race driver is helpful? Like this one,  http://www.vintagecb750.com/parts/480/35-9124.jpg

For removing races? Not necessary, I use a piece of SS round stock. Simple...

[Marks78]

Thanks Steve!  You never know when a specialty tool will actually be helpful or just an unnecessary expense. Will pass on the driver and gladly spend that $30 on something else. 

[JoeCooley]

I just use a long drift/punch and hammer for removal. A long 3/8 extension would work also but make sure it's one you don't care about. To reassemble, use a big socket and tap it in.

[Marks78]

The long drift & hammer method sounds like what I will use since I already have those tools in the shop. It usually works fairly well without doing damage (if your careful and the drift doesn't slip). I'm curious to find out if the original ball style bearings are still in there or if they've been replaced with some good taper style bearings.

[JoeCooley]

I always assume the worst. Some guys don't even know what All Balls is.

[Marks78]

Finally, a bit of an update! As is often the case life gets in the way of livin'! Lots of distractions this year so not much actual work has been done but I have ordered almost all the parts needed to get this old CB750K8 back on the road. The set of fork tubes I ordered are 23 13/16" long and are sold as standard length for this bike. I have since found that 23" is the standard length. So I had a set of springs custom made locally by "Cannon RaceCraft" to fit the new tubes. I'm not a fan of spacers and since I needed springs anyway I just had a new set made to fit. Not sure if I will like how the change in trail will affect the handling due to the 13/16" longer tubes but I figure if I don't like it I can just raise them an inch in the triple tree and get the trail back to factory specs. Not real crazy about that "raised tube" look but it shouldn't be too bad. While in the process of rebuilding the forks I also discovered something that has me kind of curious as to how it happened, one of the aluminum "lock" pieces that holds the damper rod in place had been so abused somehow, that it is barrel shaped instead of straight with a taper and it has a crack about an inch long down one side.  Fortunately CSMNL.com still sells them for about $17 USD. Of course shipping is about 3 times that, but it's one of those parts ya gotta have. So the waiting continues as I wait for the part to arrive from the other side of the ocean. Hopefully it will be a short wait! I am really anxious to get this beast on the road this summer!  Get out there and ride!!

[Marks78]

Just got the disk back from Tom at "TrueDisk".  Looks fantastic! He did a great job with fast turn-around time. I had it back one week after putting it in the mail to him. Anxious to get it on the bike and test it out, plus I just like the way it looks. Don't know how much weight loss there was (probably not even one pound) but every bit helps. It does feel noticeably lighter.
 

[Marks78]

A bit more progress (though until I figure out how to attach photos there will be no proof it's happened  ).  Got steering head bearings and front wheel bearings installed. Soda blasted the front hub and laced up the new rim with a new set of spokes (only took me two tries to get it right  ).
Also got the forks back together. Looks much better though it will not be a show and shine winner until I strip it to the frame and repaint it.
 Looks like the attachment worked! 

[SOHC4 Cafe Racer Fan]

Just got the disk back from Tom at "TrueDisk".  Looks fantastic! He did a great job with fast turn-around time. I had it back one week after putting it in the mail to him. Anxious to get it on the bike and test it out, plus I just like the way it looks. Don't know how much weight loss there was (probably not even one pound) but every bit helps. It does feel noticeably lighter.

Cal went a step further and had slots (either machined or laser cut) into his rotors. Slick.

[Marks78]

Let's see if I can attach another picture, the one attached to that post was connected to photobucket so I deleted it. I agree SOHC4 it is a slick look.  My disc wasn't slotted but still I like the drilled look.
 

[SOHC4 Cafe Racer Fan]

Truedisc did a nice job.  Did they thin the disc too?

[Marks78]

No thinning other than the material that was removed to smooth the surface of the rotor, which of course was minimal.   

[Marks78]

No work done this time but I had to share what came in the mail today.    Side covers and emblems from Frankenstuff. Very nice!

[Marks78]

After a long absence due to many factors I have finally started getting into the carbs on this very slow going project. Found several fun little items of interest.  First off -- the carbs are PD42B's not "A's", apparently from an "F" model. I don't mind this as I'm hoping the 110 main jets help it run a bit richer/better than the 105's the K models came with in 1978. This jet out of #1 carb is in obvious need of cleaning and the floats for #1 were installed upside down!?!? The good news is they don't 'appear' to be overly dirty.  At least no dried, gummy fuel deposits in the bowls. After years of hearing all the hype about Ultrasonic cleaners I decided to break down and buy one, largely due to the condition of the jet out of #1 carb and they look like they haven't been properly cleaned (especially on the outside) in a bunch of years and the fact that it's best to use OEM brass in these carbs.  So we will see. I'm hoping it proves to be money well spent. 

Question -- should I leave well enough alone and not separate the carb bodies? The hoses that connect them look to be OEM so I know they have got to be dried out and at the end of their usable life along with the o-rings, but I don't want to create unnecessary work/problems. 
I am also hoping someone has a good recommendation for the hose that runs between the carb bodies.  Right now they have clear fuel line but I don't know if that is OEM or not. I'm not a big fan of the clear fuel line, it doesn't seem to be overly durable and seems to have a shorter life expectancy, but will use it if that is what's recommended.  No leaks as far as I know but I have only run the engine three times for a total of about two minutes since I bought the bike in 2016. 
EDIT: Can't get all the pictures attached so these will have to do.   

[Marks78]

Got a new base installed on the ignition switch.  Much thanks to Tony from OregonMotorcycleParts.com for helping me find a connector that would plug in to the new base.  The original used a different style locking arm and it had broken so I had to do something.  The base came from Vintage750.com and seems to work well though it is not as sturdy as OEM.  I used a mix of new switch parts and OEM switch parts to get what I hope will be a long lasting unit that will work well.
The trickiest part of the change was getting the OEM base disconnected from the switch housing.  Once that was figured out it was an easy job. The key has to be in just the right position or it won't pull apart (or go back together easily).