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CB750 K5 Restoration

grepper

Old Bike Nerd
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Location
Lowell, MI
Last weekend I finally got around to ripping into my 75 CB750 K that I bought from cyclebuster.

Tanks, carbs and seat off... man is this bike crusty.
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Started with the exhaust. Everything just started to crumple into dust as I took them off. Unfortunately, the four inside exhaust spigot screws are stuck. I tried penetrating oil, heat, impact screwdriver... all the tricks I can do with the tools I have. I had to just cut the pipes off. It looked like some animals made a home inside the mufflers. Rusted to the bone has a new meaning, yeah I found a bone inside one of the mufflers.
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Next off with the oil tank and battery box, and everything else attached to the motor. Got all the engine mount bolts off except the bottom two and did the tip the bike on it's side to get the motor out trick.
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I proceeded to take some parts and covers of the motor, stuffing the holes of course. I also disassembled the rest of the bike. Everything is now in boxes and baggies.

Next, I plan on getting the frame and all the black parts together, clean and stripped, and then send them off to the powder coater for some gloss black.
If your in the Lansing Michigan area Elite Electro Coaters (near the airport) is a great place for powder coating. I've had them do two other bikes for me and I can't rave enough about there work. They will sand blast, pre bake, mask and plug for you before he powder coats. They do great work.

All the Red and silver (except engine) is all powder coat done by Elite Electro Coaters
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I started in on the carbs.
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Dust caps are dry rotted, haven't decided if I want to run them or not. $12 a piece at the local Honda shop.

Wow, I wonder if this bike sat at the bottom of a lake for a bit.
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Two of the bodies are trashed, the float posts totally rotted.
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Good thing I have an extra parts bike.
 
Yeah, but think how purdy she'll be when you're done.

Can you save the motor, or is it in as bad a shape as the rest of the bike?

And maybe it wasn't sitting at the bottom of a lake - maybe a landfill :) Glad to see another restoration in progress - I hate to see these bikes rusting away - good for you!!
 
that is very common for setting cb750s. i have lots of racks setting here on the shelf many just the same way. see which bodies you need.
I have pulled worse then that off bikes that looked like new.
 
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Can you save the motor, or is it in as bad a shape as the rest of the bike?
I hope so, it turns over. I've been meaning to do a compression test.

hey grepp, always fun to start a new project! some funk growing in those carbs. what are your plans with this bike?
I'm building it for my wife. We sold her cb650 and a couple of my bikes last year for some extra cash to buy a house. So she's got creative control and is leaning toward mostly stock.
 
Well, I broke down and sent the carbs off to oldskoolcarbs.com. Rick replaced the bodies with some he had. His work is well known on xs650.com. I look forward to getting them in the mail sson.
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Rebuilding carbs is more of an art than a science that I have yet to master and I have the feeling I'll be working with a lot of variables when it comes to getting this bike running right. So I figured, why not take one of the hardest out of the equation. I'll top it off with a Pamco ignition, a new set of pipes and stock air box.
 
i will go on record here, those carbs look like hell to me. spray painted, the bodies should be natural finish. looks like 3 types of air screws, no boots, connector vent links should be black hose, the correct air srews seal to the carb body, those cant. I will put pics of one of my sets on here. If those air srews dont leak, they should work ok, but they sure dont look ok. He even painted inside the float cavity, the gas will eat that off for sure, and possibly plug the low speed jet. email me at www.cyclebusters.com i will get you a couple correct air screws.
 
That's not spray paint. They are bead blasted and polished. That is the natural finish. I'll look closely at the air screws when I get them, they should match. The boots were dry rotted, I can put some on if I want to. Any special reason the connector vent links should be black?
I'll say it again, there is no paint on these carbs, they are just super clean and polished.
He has painted some carb bodies upon request for his other customers. He has 100s of photos of his work http://s591.beta.photobucket.com/user/wildmanv65/library/. He's been doing carbs for the xs650 community for years and everyone raves about his fine work.
 
its all in what you want. those carbs were 100 percent original finish when you sent them and outside of dirt, thats what they are suppposed to look like. they did not arrive at that finish by age. they never were shiny like yours are. there are only 3 shiny things on cb750 carbs, the gantry arms, the seal rings, and the float bowls are finish coated like the engine. I know its your bike, but if i was going to call my bike a restoration, and got those back i would be mad as hell. the bodies looked like the first picture brand new and never shined. go look at ebay cb750 carbs, restored bikes, google any restoration. Any CB750 purist is going to ask you what happened to those carbs. it sure looks like spray paint to me.
 
I think they look pretty cool. I would put those dust boots back on though.
Are you planning a restoration or are you going to customize you bike?
Ed
 
I got them in the mail last weekend. The carb bodies don't look as shinny as they do in the pictures. I know Honda still sells the boots, $12 each at my local bike shop. I'll probably get a set.
I'm going for a restoration, but not fully stock show. It's just not in the budget. For example, to replace the exhaust with the stock 341 system would cost between $800 and $1200. Plus, it's for my wife and stock 75 colors don’t do much for her. She will be picking out the colors for the tins. We are more aiming for a stock looking, reliable daily rider. I've never been much for trailer queens, I build bikes to ride. Plus, I plan on putting a Pamco ignition system and modernize the electronics, with automotive blade fuse box, new regulator/rectifier and such.
In short, stock for the layman, not for the judges.
 
they will and do look awesome, dont get me wrong, but I am a correct to the washer guy. I want the bolts that hold my oil tank to be the correct shoulder bolts with the correct washers. The warning beeper must function. all 4 turn signal stem bolts must be correct and face down, etc. All my long term projects and bikes i keep are correct to the wire loom clamps. I know your bike will look great, as well.

That bike you have belonged to CB750CAL, a Lifelong Cb750 enthusiast, look him up on ebay, Cal and I completed over 4500 ebay auctions, primarily CB750s, clean parts, and some other models of vintage bikes. Calvins death came at a time when i didnt have a lot of cash, so i could not buy your bike for myself. I sold that bike and all the others for his widow. We had always planned to fix that bike. I hope to see it standing tall and looking good soon. If your not using the hm341s, i could sure use the rear peg bolts. and if there are any baffles in those pipes, i am short one.
 
Cyclebuster: I can appreciate a proper restoration, and if the bike was more complete, I had the stock pile of parts you have, or it was a rare valuable model, I might go for it. In this case I lean more toward practical than pure.

As for the peg bolts, I'm going to hang on to them for now, just in case I come across a set of hm341s for a price I can live with. The baffles were rotted out as was the rest of the pipes. Rust was holding them together. As soon as I started removing them, they crumpled into dust.
 
Well there you have it, Grepper,
A Bike with a history. I'm sure that the previous owner will be proud of it when your done. I say, "Thank GOD" for guys like cyclebuster and CB750CAL for their attention to the small details and dedication to be perfectionist's when it comes to the restoration of these great bikes. Without the experience and knowledge of guys like them, and I'm sure allot of other guys on this forum, some of us would be lost. That's just MY opinion.
As for me and my 750K, I won't be going for a restoration. I'll be looking to something more customized but practical and ridable. I have no intention of really letting my imagination run wild on this build because it will be me and my son building it together and he is just learning at this point. But I see this opportunity to teach him something I have always wanted him to learn. Now, I may not be the greatest teacher but I know he, and I, will benefit greatly from this experience. And that, aside from the actual building and working on the bike is what excites me. And that is why I'm so happy to be back in the game here.
Ed
 
I am a hound for over restoring. I want to make the bike the best it can be. If Honda had our finishes available in 1975 they would have used them. In that light I say make it what you want. If it makes you happy then enough said. Isn't that what really counts?
 
Not much to add here, working very slowly on this build. I stripped the paint off all the black parts, gave them to Elete Electrocoaters in Lansing. Satin Black, picked up the frame, swingarm, trees, engine mounts, chain guard, battery box, MC, brake caliper and disc last week.
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Spent a few hours Saturday doing some polishing.
Rough shape!
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After some blasting and sanding.. almost half done
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About ready for a final polish
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Like new!
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Well, for the purists, this will blow their mind. Here is a pic of my "HondaHa" '74 CB750 with a front end from a Yamaha '82 XS650, including the 64 spoke wheel, brake caliper, forks, rotor and fender. The brake caliper on CB750's is not a good design and is reflective of Hondas last minute decision to have a disk brake instead of a drum brake on the front wheel, so my interpretation of that dilemma is to have a better brake design which Honda may have done if they had more time to complete the design. The DOHC CB750 does have a disk brake design similar to this along with the elimination of the fender braces, so my bike is just a couple of years ahead of its time.

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The bike also has a few other improvements over the original as well:

1. Seat cover.
2. Mac 4 X 2 headers and mufflers.
3. '75 Jeep voltage regulator
4. 3 phase bridge rectifier.
5. Alternator fail indicator.
6. Automatic headlight on when in gear.
7. Oil pressure gauge.
8. National Cycle windshield.
9. PAMCO ignition E/W "Ultimate" coils.

These are just modern improvements over the original near perfect design so I still get the same ride and performance of the original, including the original tiny velocity stacks in the original air box and I get to blow the original horn at the original idiots (somethings never change!).
 
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