Topic: CB750 K7 - Starting "Cafe" Build - A lot of work ahead of me!

[MarkMadness]

Hi all,

I'm a CB750 noobie who's going to attempt to get my newly aquired CB750 from rags to riches

I picked up this 1977 CB750 last week and the plan is to get it looking like a gritty cafe with air pods, white lettered tires, no fenders, and mini flashers, and a unique paintjob. 

No plans yet to relocate battery and oil tank, nor to go to a bigger bore head/pistons. 

With a new baby on the way, and my wife's patience wearing thin (this is my 3rd bike!), I've got until March to get this thing looking half decent before I kick into father mode.

As I stand now, I've got a mountain of questions ahead of me with little answers.  Hopefully, with my service manuals, youtube, and this forum, I'll be able to get through it in one piece!

Progress pics to follow.

I'll be talking to you all soon,
Mark

[SOHC4 Cafe Racer Fan]

Not too rough. You can accomplish the mild cosmetic makeover you outlined pretty cheap and fast. The key is making sure the bike runs/stops safely and reliably.

[KrautKoffin]

Not too rough. You can accomplish the mild cosmetic makeover you outlined pretty cheap and fast. The key is making sure the bike runs/stops safely and reliably.

This is where your project should start. Get that motor running well and the carbs tuned properly and the rest is cake.

[MarkMadness]

oh my God, what a rat's nest...  I've never seen so many splices!  Challenge: Try to count the number of spliced, exposed wiring, cut wires, and additional circuitry (I gave up after 20)!

My turn signal assembly needed some work (right turn signal wires melted... switch jammed and stuck in low beam, and horn button was not working).

After 3 hours of tinkering, the assembly now has new wiring and all buttons/switches work.  That tinkering ended up saving me about $75 for a new assembly.

Tonight, I attack the brake light and turn signals.

Wish me luck...

[70CB750]

You good, if you can tinker for 3 hours with wiring, the brake light and turn signals are gonna be easy 

[snowman]

Off to a good start and can't to see how the final product turns out.

Subscribed.....


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[lwahples]

I like your mind set,with saving on the wire harness.Interested in seeing how it comes along.

[MarkMadness]

I didn't get to work on the brake light and turn signal last night- date night with the wife

I did however stop off at a friends house (fellow member "Snowman") to pick up a bunch of old parts that he isn't using for his build.  Thanks Snowman 

My build is actually a little more complicated than it needs to be...  Since I live in Quebec and bought the bike out-of-province, the bike needs to pass an inspection before I can get it plated.  The problem is that it likely won't pass inspection after I've finished my rebuilt since I'll be removing my fenders, removing gauges, installing smaller flashers, etc...

So I need to build this bike in 2 parts.  The first part is get it running with the stock equipement and get it to pass inspection (hoping to do that over the Christmas holidays). 

Once it passes inspection (fingers crossed it won't be too difficult), then I can tear the bike down completely and start my "cafe" build.

Two builds in one, lucky me...

[PMacDaddy]

Will be following along, got a long project ahead of you, but luckily a long winter to go with it .

P-Mac A.K.A. Choucroute Moutarde

[MarkMadness]

Tail light and flashers are now fixed and ready to be reinstalled.

This morning, I'm going to clean up the rats nest (make sure there aren't any exposed wires), reinstall the air box, put the carbs back in, and see what I'm missing to try to start her up.

If she does actually start up, she's going to be loud (4 into 1 with no muffler)!  Be thankful you aren't my neighbor.




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[J-Rod10]

Spend the money on some K&N's or Uni's. Otherwise it's going to be a pain in the ass to tune your bike, and the cheap pods don't do much in the way of filtering.

I'd at least run an inner fender in the rear, or you'll just be throwing debris straight into your filters. Bad news if you get caught in the rain.

[snowman]

Spend the money on some K&N's or Uni's. Otherwise it's going to be a pain in the ass to tune your bike, and the cheap pods don't do much in the way of filtering.

I'd at least run an inner fender in the rear, or you'll just be throwing debris straight into your filters. Bad news if you get caught in the rain.

Running a set of pods is something that I've been thinking about also, but from what I've read so far is that they can be a real PITA to tune your carbs properly.  Unfortunately this is something that I'm not to familiar with ( playing with the jets) and frankly it scares the crap out of me. ;-)


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[KrautKoffin]

Spend the money on some K&N's or Uni's. Otherwise it's going to be a pain in the ass to tune your bike, and the cheap pods don't do much in the way of filtering.

I'd at least run an inner fender in the rear, or you'll just be throwing debris straight into your filters. Bad news if you get caught in the rain.

Running a set of pods is something that I've been thinking about also, but from what I've read so far is that they can be a real PITA to tune your carbs properly.  Unfortunately this is something that I'm not to familiar with ( playing with the jets) and frankly it scares the crap out of me. ;-)


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Don't let the geezers on here scare you. Pods aren't impossible to tune, APE also makes great pods for certain applications for half the price of K&N's. Do your research and you'll see that pods are a great alternative to the stock airbox.

[J-Rod10]

Great alternative indeed. Didn't mean to imply otherwise. But, they are a not so great alternative if you buy cheapos that don't really filter, i.e. Emgos.

[MarkMadness]

I'll be sure not to skimp on the pods then, thanks for the advice.

Put the electricals back together and low and behold - success!

The only problem I have left is my flasher relay. I've got the tridon 2-pole   flasher, but it doesn't seem to be working. I've hooked it up on my workbench with a 12V battery charger, but it doesn't seem to want to flash.

Have you guys ever tried troubleshooting these relays?  Or should I just go to Napa and pick up a new one?  Is there a better one to get then the electric/mechanical one that's in there now?






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[KrautKoffin]

Great alternative indeed. Didn't mean to imply otherwise. But, they are a not so great alternative if you buy cheapos that don't really filter, i.e. Emgos.

Agreed. Emgo makes such crap products and they are pushed by companies like DCC which sucks.

[MarkMadness]

Realized my rear brake switch was missing the spring which connects it to the brake pedal.

Rummaged through my basement, and fabricated one out of an old doorstop (that should be good enough to get me through inspection). I'll be sure to order the real part on my next online order, but it'll do for now.




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[MarkMadness]

Picked up a new flasher relay at Canadian Tire and my flashers are now up and running.

That means my electrical work is done (until I tear the bike down again after my inspection).

Now i shift my attention at the carbs and air box. Fought with the carbs for over an hour to get them installed, but the air box isn't cooperating.

I've tried soaking in hot water and using a heat gun to soften the airbox boots, but no luck.

Anybody have a sure-way method of getting this airbox installed?

[MarkMadness]

Made up a fuel line yesterday, changed the oil, and decided to try to start her up.

After a bit of persuasion, the bike turned over and came to life (ish):

Obviously it's not running great (definitely going to need to try it out with the airbox installed), but at least it's a start.

One of the problems I found was that carbs #2 and #3 we're leaking fuel from the the overflow tubes. I looked into it, and it turns out that my tubes were cracked (crack might be hard to see in the pic):


I read up on the problem on the forum and decided to try to fix it by soldering the crack shut. So after 30 minutes of messing around, I finally patched up the crack and stopped the leak:


I reinstalled the carbs and fuel line, and so far, so leak.

Next step, installing airbox...

[MarkMadness]

Urgh, still no luck with getting this f#*king airbox installed.

Decided to give up for now and looked into my front brakes instead.  When I apply the front brake, the piston would engage, but it would not release. Drained the brake fluid, removed the caliper from the bike, and decided to open it up in my workshop.

I managed to get to bleeder nipple bolt out (it was pretty rusty), but the piston was a different story...

Checked the forums and tried the air compressor trick - no luck.

Went to plan B and used a grease gun. Managed to get about 1 thread on tight and it popped out like a charm.



I was able to salvage the rubber seal and soaked the rusty parts in some rust removal juice from Canadian Tire.

Long story short, got the brakes "rebuilt", reinstalled, and bled so that my brakes no longer stick.

One less thing to worry about for the inspection.

[MarkMadness]

Hallelujah, the airbox is installed!

It took my brother-in-law and I about an hour and a half to get the damned thing on.

It was a combination if soaking in hot water, blowing hot air from my heat gun, generous amounts of jiffy lube, and brute force that finally got the thing seated.

I don't care how hard it is to tune the carb with airpods, I'm definitely not going to go back to the original airbox for my rebuild.

I also ordered my muffler from Carpy (Scorcher).  Hopefully it won't take too long to get here so I can hear what she sounds like.

All I need now are a few borrowed parts from a friends working CB750 and I should be ready for my first attempt at an inspection.

More to come

[iron_worker]

Your airbox shouldn't be that hard to install. I'm guessing your velocity stack rubber is hard as rock which makes it very difficult. I replaced those on my K4 though I've heard some of those items can be unobtanium for the K7-K8 bikes.

IW

[ogsmakdade]

I had someone on here tell me to soak any hardened rubber products (air box/ carb boots, for gaiters) in wintergreen.  said it works wonders.