1976 CB 750

legitmw

legitmw

Been Around the Block
Hello all! Finally getting in the game! Been a member on here for a while and have spent countless hours reading. So many amazing builds. Today I finally bought a '76 CB 750 and plan to tear it down and build a beautiful cafe racer. This is my first bike and first mechanical project of this size, so bear with me. Here she is in all of her ape hanger glory.

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She does not currently run, but has good compression. So far I've taken the carbs off and will clean them tomorrow. Also took off the ape hanger handle bars as I couldn't stand to see them anymore. I plan to get her running, then strip her down to the frame and clean and repaint it and then build it from the ground up.


The only real problem that stands out to me is the wiring. Someone took it upon themselves to add a few spools of wire onto my baby. There is an extra kill switch with wires leading who knows where. The ignition seems to be moved to a new location in a very shady way. There are just so many wires all over the place. I'm going for a pretty simple look. The only things I will need wires for is the ignition, headlight, tail/brake, horn, and I think that's it. Not sure if I'll use blinkers. So I think I will just strip all the wires off and add the few simple ones I need when I get to that point.


First post and I already have a question. How does one go about cleaning the carbs? They're not terribly dirty, I know how to disassemble them for the most part, should I just put the whole thing in some sort of paint thinner concoction to eat all the gunk away? Should I get a rebuild kit to replace all the little parts?


Thank you in advance for the indescribable amount of help I'm sure I will receive over the course of this build. I am very scared and I also look forward to it very much.
 
Welcome abord. You can definitely let go of that stockfish wiring loom. Good luck on the build.
 
Like CAFEMAD said, Im a few stages ahead of you in my build. Look into doing a Pine-Sol soak and get a rebuild kit to replace the small items. That should get you in pretty good shape moving forward.

Good luck,
Matt
 
legitmw said:
How does one go about cleaning the carbs? They're not terribly dirty, I know how to disassemble them for the most part, should I just put the whole thing in some sort of paint thinner concoction to eat all the gunk away? Should I get a rebuild kit to replace all the little parts?
Click to expand...

There are threads all over the forum where people have cooked their carbs in lemon juice, or PineSol, or any number of concoctions. Many of those threads show the aftermath of corrosion and fucked up carburetors.

You are cleaning carburetors. Use carburetor cleaner fer fuck sake! (not rocket science) If you are too cheap to buy carburetor cleaner, then maybe you have chosen the wrong hobby. <G>

You can get a one gallon can with a parts basket. Put your parts in it and soak them for 20 minutes, then scrub a little with a flux brush. Then, use aerosol carb cleaner to blast off the dirt, and flush out the passages. Finish with compressed air.
 
I think we have a good bit of carb cleaner somewhere in the garage, so I'll definitely use that. Hopefully I can get to it tonight. I am a full time college student, work part time, and I'm also an officer candidate in the Marine Corps, so spare time is hard to come by.
 
i have '72 carbs , make sure u use compressed air to blow dry carbs after using carb cleaner to avoid the white corrosion
i rebuilt my carbs last season . a friend who is big into racing bought an ultra sonic machine .. it is a machine that uses vibration to forces a cleaning solution through all the smallest orfices of a carb .
for 50$ a carb you cant go wrong
 
I think I'm gonna keep the wheels for now.

It's good to say that it's now up and running.

I took off the carbs, after wrestling against the rock hard carb boots for a while, and took them apart cleaned them with just standard carb cleaner in a spray can. Then soaked my carb boots in 1oz of wintergreen oil and a quart of water. I didn't want to wait and order wintergreen oil online; all I could find locally was two .5 oz bottles at $6 a pop, but it worked wonders.

Replaced the oil filter and put fresh oil in. Took the gas tank off and cleaned it, quite noisily, with a bunch of nuts, screws, and bolts and some rust killer from an auto parts store. Haven't put the tank back on yet as I need new fuel lines (old ones were worse off than the carb boots). I just sprayed some engine starter in the carbs and kicked her over and she roared to life.

I still am not sure what direction I want to take it when it comes to the tank/seat. I do know that I want to fab up some sort of removable seat cowl, so I get the classic cafe look, but can still take the ladies for a ride.

Question
What's the best battery? Is there a standard one that everyone gets? I see a lot of guys remove the stock battery holder and hide it somewhere in the seat. What kind of small batteries are those? I just grabbed a 4-wheeler battery to start it up, so I need to be getting one and might as well get one of the small ones that I will be needing later on.
 
If your tank had some rust in it I would recommend putting a liner kit through it before running it on your bike. ;)
 
I knew I was forgetting something! Thanks. What kind of liner do you suggest? I'm 90% sure I'll be getting a new tank anyways, but for now I wanted to clean this one up to use it.
 
Welcome to the site man and looks like a good start . Take your time and learn your bike first thing is get yourself a manual !! Then read it and keep it handy as youll use it all the time .
 
Good progress today. Well I didn't do a whole lot, but I did get the fuel lines hooked up and rode around a little bit. I'm just getting everything in decent working order before I take it all apart to do a full rebuild.

Carbs are pretty clean. I'll soak them again when I do the full build and get them all shiny. K&N pod filters will be ordered soon.
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Here's a pic of how I got it running. Used a 4-wheeler battery, which doesn't quite fit in the battery box. Had to clamp some mini jumper cables onto it and hook it up to the bike. Unfortunately this made for an uncomfortable riding position, left foot passenger peg, right foot front peg, sitting far back on the metal frame. It was a blast nonetheless.
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More sketchy wiring. Whoever had this before me decided a centrally located key and the kill switch on the controls were not enough, so this was added.
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When I was first riding around, I stalled out a few times. Thought maybe the clutch was a little messed up or the shift pattern was different than I thought, then I realized this is geared really high, at least I think it's really high. I think the stock rear sprocket is 48 teeth, mine is 32. Was able to go pretty quick in 1st gear.
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Once the bike warmed up, it idled pretty well and when I was revving it, it sounded real nice. Just gonna do some final tuning up and fix the front brake (not working at all, no fluid so hoping it's a simple fix). After that I'll be looking to start stripping everything apart. I REALLY need to figure out my tank/stock combo. I'm moving faster than I thought I could and need to have my cafe parts ready. Clubmans should be here Tuesday, in the end I think I'll end up with clip ons, but went ahead and got clubmans to try them out since they're way cheaper.
 
I have a couple questions about some new parts.

Question
I'm looking at getting pod air filters. I was originally looking at the K&N ones for around $100, but now I'm seeing there are some no name brands that have very similar air filters for only $20 or $30. Will there be a noticeable difference between the K&N's and cheapo ones? Am I just paying for the name with the K&N's? I have no problem paying for the K&N ones, but if I can get similar ones for cheaper then it's a no brainer.


Question

What is the best size chain and sprocket to get? Currently my rear has 32 teeth, geared way too high and I am going to change it. Am I best going back to the stock ratio of 18/48 with a 530 chain? Or is there a more preferred set up?
 
legitmw said:
I have a couple questions about some new parts.

Question
I'm looking at getting pod air filters. I was originally looking at the K&N ones for around $100, but now I'm seeing there are some no name brands that have very similar air filters for only $20 or $30. Will there be a noticeable difference between the K&N's and cheapo ones? Am I just paying for the name with the K&N's? I have no problem paying for the K&N ones, but if I can get similar ones for cheaper then it's a no brainer.


Question

What is the best size chain and sprocket to get? Currently my rear has 32 teeth, geared way too high and I am going to change it. Am I best going back to the stock ratio of 18/48 with a 530 chain? Or is there a more preferred set up?
Click to expand...

Well the air filters will say you get what u pay for ! I run K@Ns on my 500 and UNI on my FJ both are nice. The UNIs are lil cheaper but both are reusable not sure if the cheap ones are !
As for the chain I myself would start with stock set up and go from there !
 
Finally got my front brake apart. I had been trying everything, finally I filled a grease gun with some brake fluid, and thankfully the threads from that perfectly matched the brake caliper, so I screwed it in and started cranking. By some miracle the piston popped right out!

K&N pod air filters and a new o-ring chain and stock sprockets will be here next week. Throw those on and get the brake working and the bike will be running 100%.

Then it's time to find some rear sets that will still allow passenger pegs, make a brat style seat with a removable cowl, and figure out what tank to use.
 
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