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Author Topic: 76 CB 750 F1 brought back from the grave.  (Read 2685 times)

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Offline Hon3ybadger

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76 CB 750 F1 brought back from the grave.
« on: March 29, 2014, 10:41:01 PM »
Good evening everybody. Tonight I'm what I'd consider "halfway" though my build. I bought a two basket case CB 750's from some guys garage. His sister sold it all to me for $550 bucks. One bike was just a titled bare frame plus a rear swing arm, fender and master cylinder. The other one was a rolling frame with just about everything except an engine and carbs and oil tank.

In the boxes laid Honda treasure!! I found the engine (with a broken cam tower), carbs, a replacement valve train, some aftermarket 4-1 exhaust and random bits galore. Sadly only one side cover and it was broken.

I purchased the bike Feb 2nd. So it's been two months now. I didn't have my good camera till this week so sorry for the blurred pictures. I drove over my phone with a truck and trailer.
« Last Edit: April 06, 2014, 04:30:06 PM by Hon3ybadger »
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #1 on: March 29, 2014, 11:51:53 PM »
So those pictures above were day one right after rolling it into the garage. The following pictures are week one. I was just cleaning and polishing stuff. The exhaust came out better than I thought. And I got a little crazy with the rear brake bracket.
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #2 on: March 30, 2014, 12:01:21 AM »
Week two I rebuilt the engine from the cylinders up. I was going to go further into it but judging on the amazing looking cylinder walls and pistons I decided to just do a freshen-up and see how she ran first. Replaced all the seals and gaskets. Swapped out the O-rings on the oil pump for fresh ones and cleaned the old dirty oil out of it. I also revived the rear master cylinder but I have no pictures of that. It was in horrible condition!!!
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #3 on: March 30, 2014, 12:14:16 AM »
Week Three: Started playing with the media blaster and "the works" to clean up my tank. I found 1 day of the works 50/50 with water followed by 3 days white vinegar followed by water/baking soda rinse gets all the flaky rust pretty well removed. I don't know how long this bike sat around but it did have four pin hole leaks on the left bottom seam. Judging by the pin holes on the left and the cracked side stand bracket I'm sure it sat for many years leaning to the left. Also pictured in week three is some freshly painted gauges and headlight bucket. Not pictured are the motor mounts, battery tray and other bits brought back to life.
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #4 on: March 30, 2014, 12:31:48 AM »
Week Four: Carb week. I checked the lists and from the numbers on my frames, carbs, and engine its all late 75- early 76 F model. The tanks original color looked burgundy and the tail piece is green. So I Think I have a matching tank but the seat must be off an A model. Anyway back to Carbs. Please give me your opinions!!! I put the needles on the 3rd clip, set the floats at 26mm, and using (105 main/40 slow)Jets (stock). It was set on the highest notch and the plugs looked lean on the two cylinders without the broken cam tower. No visible cracks in the overflow tubes! In your opinion, with the stock airbox, stock jetting and stock-ish exhaust= Do you think it will run? Decent enough to tune?
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Offline KayOne

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Re: 1976 CB 750F brought back from the grave.
« Reply #5 on: March 30, 2014, 10:54:16 AM »
Looks like a great project. The exhaust pictured is a 77/78 CB750 F four into one...pretty rare and the nicest in IMO.
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #6 on: March 30, 2014, 02:24:37 PM »
Interesting. I didn't see any numbers on the exhaust anywhere. But I don't know where to look honestly.
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Offline Hon3ybadger

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Re: 1976 CB 750F brought back from the grave.
« Reply #7 on: March 30, 2014, 02:43:03 PM »
Week Five. So now we are up to the first week of March. Sorry everone I'm posting all this weeks later. But I finally got my good camera so now its worth it. Anyway I finished the motor work for now. I don't know how the clutch or starter will be but I'll find out when its running. Enjoy more blurry pictures!

 
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #8 on: April 06, 2014, 05:03:32 PM »
Sorry about the long pause gentleman. I've spent too much time in the humor and polls section.

Ok so we are onto week six. I took the frame to powder coating and finished taking apart the donor bike. My brother thought clubman bars were normal bars turned over. As you can see it just looks weird and hits the tank. lol
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #9 on: April 06, 2014, 05:16:03 PM »
Week 7. While patiently waiting for my frame to come back I started to dig into the suspension and steering bits of the bike. Cleaned up the rusty old wheels. Going to respoke them and hubs got new "all balls" bearings and seals. One note on the speedo drive: the seal all balls sent with the front hub kit is 2mm to large to fit inside the housing. Since my old one was perfectly fine I just reused it. On another note THANK YOU UPS for delivering straight to my door, unlike those morons at USPS. But THANK YOU again for damaging my brand new parts. Remember its a box, not a F#^%! soccer ball!
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #10 on: April 06, 2014, 05:32:44 PM »
Week 8. I think that was last week. Anyway Got my frame back. It's freaking amazing! But I already scratched it. :( In the picture of the vin you can see I had the powder coaters tape over the vin after the first coat and before the second coat. Two coats can bury the vin depending on the thickness. One of the pics shows Carpys retainer tool. I filed the sides of the round pegs to get a better bite on the front hub retainer. Worked pretty well after drilling out the punch marks. And the tank had some pin holes along the left side from being leaned over for so many years. I used a propane torch, metal putty knife and metal repair solder to fill them in. Tank was then filled with "the works", flushed and filled with seafoam, gas and a little 40w oil. No leaks, No rust!
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #11 on: April 06, 2014, 05:58:38 PM »
Week 9. Alright we are finally caught up! So this week I got the engine in the frame. That is the tightest fitting engine to frame I've ever dealt with. So glad I learned the tricks from this you wise old timers. That was really hard and heavy all by myself. I mounted the rear shocks, still waiting for the bronze swing arm bushings to come in. Got the front all lined up and ready for tires. Lacing spokes was not that hard although truing the wheel was time consuming. The head bearings were no sweat at all. Side note: My old bearing stack was 18.5 mm and the new one was 18.0. The top triple clamp uses the D washer and it snugs up fine.
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Offline SOHC4 Cafe Racer Fan

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #12 on: April 06, 2014, 09:03:06 PM »
Nice semi-roller.
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #13 on: April 09, 2014, 03:50:16 PM »
Friday I'll be able to purchace the swingarm bushings and the tires. I plumed most all the electrical, installed the center and side stands, Oil tank and gauges. Building this bike faster than my wallet can go.  :-\

I question I need answered. What size bolt holds the Tach cable in the valve cover? I measured the hole diameter at 4.5mm. The bolt kit I bought from 4into1 doesn't come with anything smaller than 6mmx1
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Offline Don R

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #14 on: April 09, 2014, 09:16:41 PM »
My 76 F likes 110 main jets. float level is critical too. My PO drilled my jets, that was hard to find. I just love riding it. I did the double disc front it's good too.
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #15 on: April 10, 2014, 05:31:53 PM »
When I rebuilt the carbs I set the floats at 26mm and used new 105 mains. Needles on the third clip. Figured returning to "stock" tuning would give me a decent baseline to start from. Good idea?

I flipped the forks and went with slingshot braided lines. Dual disk is in the plans once the wallet gets revived. 

DOES ANYONE KNOW THE BOLT SIZE FOR THE TACH? Bike bandit says its a 5x25mm. Whats the thread pitch?
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Offline Don R

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #16 on: April 10, 2014, 08:16:45 PM »
Sounds like you are on track. I believe Hondaman thinks these carbs are a bit lean from the factory due to mileage and emissions concerns. The added heat reduces life of the exhaust guides and rubber parts in the head.
 I was going to flip my forks but I had already made a right side rotor fender so for now the calipers are in front. In the rear makes sense, especially when honda did it in 77.
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No matter how many times you paint over a shadow, it's still there.
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #17 on: April 10, 2014, 08:38:05 PM »
I have been watching Tweakins' 915 build. The oil cooler and bypass valve seem to be a solid investment. I have an oil cooler on my car and it makes a world of difference in engine life. 30 year old Volvo at 350k and still going strong.

I don't have a picture yet but I mocked up the front fender on the flipped forks (so the fender is technically backwards). I need a tire to see how dorky it looks but I have a feeling its going to be nose high like a motorcross bike. I've never ridden a 750 with the forks flipped. I'm excited to see how different it feels.
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Offline Hon3ybadger

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Re: 1976 CB 750 F1 Rounding the last corner to the finish line!!
« Reply #18 on: April 23, 2014, 11:40:20 PM »
Well I'm working on having the pictures up later tonight. Since whenever my last post was, I put my project in full steam ahead and she's far surpassed my wallet to the finish line. :( Luckily friday I'll be able to install the oil press. gauge, buy some darn oil and get her to sing!

You may notice the forks are not flipped, due to me not knowing if the front hub can be turned around, I had the directional tires installed so the hub is forward. And due to the $$$ restraints I've drilled my own rotors and postponed the dual disk set-up for later on.

On a sad note I got to looking at the seat pan and seat and determined it was to damaged to ever be original again. I've taken it apart to address the rust and see about redesigning it as a single seat pan with new foam and wrap. Same story with the tank. The right side is dented so bad the badge mounts are not straight. So I'm forced to fill those in and do a naked tank.
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Offline greenjeans

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #19 on: April 24, 2014, 02:29:10 PM »
Great start -

What brand of metal repair did you use for the pin holes in that tank ?
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #20 on: April 26, 2014, 02:08:08 AM »
I don't remember but tomorrow when I'm in my garage I'll try to remember to get a photo of it for you.
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Offline calj737

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Re: 1976 CB 750 F1 Rounding the last corner to the finish line!!
« Reply #21 on: April 26, 2014, 04:37:55 AM »
Quote from: Hon3ybadger on April 23, 2014, 11:40:20 PM
Same story with the tank. The right side is dented so bad the badge mounts are not straight. So I'm forced to fill those in and do a naked tank.

Is it worse than these?

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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #22 on: April 26, 2014, 04:52:16 AM »
Yes. Its like those but the whole length of the badge mount. Almost like the PO thought he could make knee indents by dropping the bike on rocks. In an earlier picture you can see the mountain of bondo covering the tank dents. I know I have one picture of the dents. I'll find it. Sorry guys I've been lazy about posting pictures lately.
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #23 on: April 27, 2014, 07:15:36 PM »
Good news! She runs!!! Nothing like a complete teardown and rebuild in ten weeks time. All I have left is bodywork on the tins and tune the carbs hopefully with a full Kerker exhaust. Enjoy the photos
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Offline Hon3ybadger

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Re: 76 CB 750 F1 brought back from the grave.
« Reply #24 on: June 20, 2014, 12:08:14 PM »
Ladies and Gentleman I present to you a beautiful F'er that doesn't run worth a damn. The ignition system keeps acting up. But what you see is not paint. It's all vinyl wrapped. The seat was chopped down from it's stock size. Tail light is designed for show trucks and lights up bright red.
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