Topic: CB750K2 Project Virgin

[CaliCafe]

I just bought a 1972 CB750 today, the test drive was my first time on a motorcycle in FOREVER.  This is also my first, very own motorcycle, fourth vehicle total.  Growing up, we got to ride Granddad's motorcycles.  It has quite a few quirks that I will be trying to work out.  It can currently only be hot wired, fork seals, all new electrical system, kill switch activates when it is not supposed to, rear shocks, rear tire has a leak that only lets out approximately 10 psi, randomly.  It drove 100 miles without losing any air but after being parked for about 15 minutes, the leak happened, it was loud and fast.  The air came from where the spoke meets the rim...  There is a slight noise that sounds like it has something to do with the exhaust.  Of course, it needs a lot of cosmetic look.  This bike came from New Zealand.  It was imported to the US when the original owner finished his vacation.  It then sat in a garage for a very long time, not even registered.  The engine was rebuilt in 2002 and has approximately 10,000 miles on it since then.  No idea how many miles actually are on it.  With a 100% new electrical system and a few minor mechanical things, this will be a rock solid bike.  Then I get to work on the look of my ride.  

I saw one website that said 1972 CB750 was marked as a K2.  Are there no other nomenclature variations for that year for 1972?  The engine number is CB750E2200596.  I know how to break down the VIN for a car but not for a bike.

She ain't too much to look at right now...  

[rickmoore24]

Welcome to the boards! You've got a great starting point. Much better than what I started with. Also, heres a link to engine and frame numbers. Keep up posted on your progress. Good luck!

http://www.sohc4.net/index.php?q=content/serial-numbers

Rick

[CaliCafe]

So, I guess I should give you a 24 hour update.  I have removed all electrical that wasn't connected to the motor.  All of it has to be replaced.  I also removed the seat, gas tank, fenders, lights and battery housing.  I wish I knew more about this stuff.  I have to replace every single wire that does not come out of the engine.  All the electrical components work great, just the wires are screwed.  Any recommendation on where to get all the wires with adapters on them already?  If not, I can just go to Al Lasher's Electronics and get started on it, would probably also be a lot cheaper to do it all myself anyways.  I also need to get some tools.  Removing those rusted bolts was not fun while using nothing but a couple pair of knucklebusters and a can of WD-40. 

Think a grand was too much for the bike in that condition?

Updates will not be as frequent as I would like as I work for the State of California.  What that unfortunately means is that I get paid by the State of California.  2 months currently with only receiving half of my paycheck...   lol

Thanks for the welcome Rick.    I thought this board would be a little more active than it seems to be.  Just an observation.

-Adam

[CaliCafe]

Apparently this is a K3.  My engine # starts with E220...  It was sold to me as a 1972, it is also registered as such.  I guess it really doesn't matter and I should stop worrying, but it is bugging the hell out of me.  lol    I stressed out for months over my 318ti over whether or not it was ClubSport or not.

Anyways, I am now sitting here looking at the wiring harness.  I think it is mostly good.   I can either test it or get testing tools tomorrow.  There are some cut wires though, not done by my hand.  the wires to the taillight, rear turn signals were out right missing, the four wires that you use to hot wire the bike were cut and the 2 wires (red and blue) that I don't know what they go to.  There were some other wires that were missing but the plug is still attached to the wiring harness.  I am going to study the harness and the bike's schematics and I guess I will be back when I know something new.

[traveler]

look at your VIN tag on the headtube......if it is a later model 1972, like 9/72 or 10/72, then it is a 1973 MODEL YEAR built in LATE 1972.  This would make your bike a "K3".  You have to remember, these bikes were built in Japan, and shipped to the USA on a barge.....took time to get here.

~Joe

[CaliCafe]

I haven't seen any numbers on the frame.  I think it was painted.  There definitely isn't a tag stuck anywhere on the bike.  The 750Four badge was falling off the side, that's the only thing even close to a tag besides the license.  I was told this one was bought in NZ originally.  I read someone else's post on here and it said he had a 73 but it had a bunch of 72 parts.  Maybe mine is the opposite.  Are 72 and 73 parts interchangeable like that?  Were there even any changes besides serial numbers?  lol

I'm a lot less worried about that than my electrical situation.  lol    Trying to find the wiring harness for about $150 is not proving to be easy.   This kill switch problem is getting me too.  I think I just have to replace the whole device.  The switch is a little loose and if it is not taped down, it randomly kills the engine.   I have to get the electrical sorted ASAP so I can get on the road a little bit. 

I won't be able to do much until the weekend.  I work 60-80 hours a week.  Project Devil Dog is definitely under way though! 

[CaliCafe]

So, when I went out in the morning to look at the frame, I could barely make out the number, bad paint job, and the frame is K2 but the engine is K3...  I'm assuming that all the parts are interchangeable with K2 and K3?

I have a couple questions about the brakes.  If I replace the forks with some that are wider and a thicker front wheel, would I have to replace the rotor and brake unit with a different one?  I really know nothing about working on a motorcycle.  I'm doing some reading but I still have some questions.  I know that I do not want to lower the bike, I already have back problems.

I saw a CB750 online with a fat front wheel.  Gave it a really cool look.  The owner didn't give much information but he said he had to put wider forks on to fit the wheel.  That's what I am trying to do.  The entire front brake system needs replaced anyways.

[traveler]

You will find alot of info on this site....try the search function, and if unsuccessful, chat up guys on here like "IndustrialCafe"...he has done some fork mods recently.

K2 with K3 engine?  Not that uncommon, as these bikes are OLD, and the original motor was probably worn out, and replaced with another engine in better condition.

If you want it 100% stock restored, it COULD be an issue, but if you are building a clean rider, then no worries.

~Joe

[CaliCafe]

Nah, I got this bike with intentions of customizing it.  I don't plan on selling this bike.  I'm finding some good information on a variety of sites.  I just wish it was easier to sort through.  lol    Anyway, more in this thread when I am able to make some progress.  I am working on running fresh wires but I really have no idea what I am doing with the alternator, starter or anything.  I really don't want to have to load it on a truck...   :'-(

[rickmoore24]

As far as wires I just sacked up and got a brand new replacement main harness from Yamiya. Unfortunately it aint cheap.  It made things way easier though, it's pretty much plug and play if you match up the proper controls and keep the stock electrical system. Will you be relocating the electricals to under a seat bump? If so then you'll have to do some modding for sure. Be thorough in your board searches, I know I've spent a lot of time searching and I've found all the answers to the questions I had. it just takes a bit of wandering around on here.

[fastbroshi]

  You said you were replacing all of the electrical system.  Why?  Was it just fried or hacked up or what?  If it's because it looks dirty and decrepid don't count it out, you'd be surprised what a little cleaning of those conectors will accomplish.

[CaliCafe]

The shielding was not in good condition.  Exposed wires in areas.  I just didn't feel comfortable riding with those wires being live that close to my bum.  I got a harness from cmsnl.com.  137 USD shipped.  It is a reproduction but the images looked great and it appeared to be exact.   I will be relocating the battery and oil tank eventually.  I am a low-level, health-care worker that gets paid by the state.  This project may take some time.   lol

Next, I will be building a headlight housing that will have room for a mini tach and speedo and I will clean up the streering stem area at that point.  New sleek control switches, remove the light panel and mount lights in the headlight housing and some drag bars with bar end mirrors.  I have never done carbon fiber molding before.

[MickeyX]

I'm not sure what you mean when you say this board is not active. This is one of the most active I've ever been to. You will get more attention on your thread if you have a good title. Putting that you are new won't get much attention. You may want to put the kind of bike you have or a specific question in the header. It really helps. There are 100's of projects ongoing in the project thread. Most people don't have the time to click on every one just to find out what kind of bike you are talking about. Just trying to help. 

Also, you may want to keep the parts you take off and offer them for sale on here or feebay. It will help you fund new parts. We all do it.

As for the wiring, get some dielectric grease and put it on your connections. It will keep them nice.

Good luck on your build.

[CaliCafe]

Not that the board isn't active.  It isn't AS active as I thought it would be, considering how many old ass bikes I see on the road in Cali.  lol

I will be selling what I can, but most of everything will be used again, if for just until I can afford to replace it.  Of what I tested,  the electrical components are still a-ok.  I will be replacing a lot of stuff but over the course of a year or two.  Next, all the handle bar controls will be replaced with a custom control board that will be mounted under the bugshield on the steering stem.  I just ordered the hardware for the panel controls.  I'm going for the minimalist look.

Dielectric grease?  Don't know what that stuff is, but, OK.
http://www.allelectronics.com/make-a-store/item/M20S-9/MECHANIC-ALL-TM-LUBRICANT/1.html   

How's that for a title?  Wasn't really thinking that there are so many different bikes on here.  Last vehicle group I joined was 318ti.org, great site if you have an e36/4.  You just gotta love inline fours... And thanks!  

[CaliCafe]

I just got a bunch of parts from various stores.  Time to replace the final drive sprockets and chain, rebuild the rear wheel and a lot of rust to bust.  I got a new triple clamp that has a modified bridge, hopefully it actually fits.  I've built light brackets for the fender-less tail end that fit nice and snug under the rear seat.  Just need to buy some LED turn signals.  I have a new Halogen headlight with a new bucket and LED tail light.  Cleaning and polishing the rear hub and exhaust today.  I still need to build some tools to remove these wheel and steering bearings.  I have to buy some new exhaust seals, the half circle ones under the brackets could be broken in half if I actually tried.

In a couple of months, I will have a chance to buy a 1996 BMW R1100RT for a couple grand.  After I get the beemer, I can really get into this SOHC project.