Author Topic: 1972 CB 750 restoration after a 40 year nap (Read 17330 times)

autotec · « **Reply #50 on:** October 21, 2015, 09:31:14 PM »

I don't want to bore you guys, but tank is clean. Thanks for all of the advice, this has been the worse tank I have ever had to deal with. As I found out, the best thing to stick in it to "rattle" it were wing nuts. If anyone wants to borrow them, let me know. LOL. On to the carbs.

Bowls are soaking, I'll let everyone know how they come out. I figured I would try something new. (Pine-Sol)

gwallis · « **Reply #51 on:** October 22, 2015, 03:29:01 AM »

I have used Pin-Sol in the past...works well. However, you do not want to leave them in too long... overnight should do in most cases. As far as the discoloration is concerned.... just wipe the down with an oily rag (Marvel's Miracle Oil) and they will shine right up!

autotec · « **Reply #52 on:** October 22, 2015, 06:34:35 PM »

The last two responses left me a little concerned since I was stuck at work late today. The bowls soaked for about 24 hrs, and I was surprised that when I got home everything looked great! The only thing I noticed was they have a layer of clear coat or something on them. When I sprayed them with carb clean, a coating on the outside turned soft and rubbed off. I didn't get it all of, but the metal under the clear looks great. So I have some more work to do on them.

On to the carbs themselves, I have never run into a set this gummed up. All of the floats are stuck to the point I'm afraid of damaging them. So I figured I would soak the entire carb body to see if I could free up just one. I'll check it in the morning.

Thanks, Justin

Stev-o · « **Reply #53 on:** October 22, 2015, 07:47:15 PM »

Yes, they are gummed up alright, bike was put away with full float bowls.
I've had worse - bowls full of white dust (corrosion)

autotec · « **Reply #54 on:** October 22, 2015, 08:33:28 PM »

Quote from: Stev-o on October 22, 2015, 07:47:15 PM

Yes, they are gummed up alright, bike was put away with full float bowls.
I've had worse - bowls full of white dust (corrosion)

Ouch, thank god I didn't have to deal with that. Right now I'm just feeling lucky I only have do deal with old fuel. The float did come out after a little bit of care on the first carb. I was hoping a quick clean would cure these, but I think I'll be putting in floats and needles too. Just to be safe.

mrbreeze · « **Reply #55 on:** October 22, 2015, 08:40:45 PM »

Keep in mind when you clean the other carbs.....the towers that hold the float pins on are very easy to break. Be real careful not to force anything. I've never broken one....someone here warned me about it many years ago. There is a member here that can weld them up if they do break but the only other thing you can do is get a new carb body.

worst650ever · « **Reply #56 on:** October 23, 2015, 04:41:37 AM »

Quote from: calj737 on October 23, 2015, 03:05:05 AM

Do not replace your needles unless absolutely necessary. Aftermarket needles, despite their listing, do differ in their taper. T

Oh dear Lord, this, this so much. I spent months fighting with my 360 only to put the stock brass back in and have it purr like a kitten. Replace the seals, but if you can, save the stock brass or buy Honda / OEM carb maker brass. Most of our old junk has so few miles on it that the brass hasn't had a chance to wear out yet.

autotec · « **Reply #57 on:** October 23, 2015, 06:56:01 AM »

Quote from: calj737 on October 23, 2015, 03:05:05 AM

Quote from: autotec on October 22, 2015, 08:33:28 PM
...but I think I'll be putting in floats and needles too. Just to be safe.
Do not replace your needles unless absolutely necessary. Aftermarket needles, despite their listing, do differ in their taper. The stock brass should clean up nice and bright with proper cleaning. Don't use aggressive scouring pads as it will alter their sizes. Chemicals and very thin wire (guitar strings are popular) to dislodge any accumulated gunk in the orifices is the best method. Berryman's Carb Cleaner is popular too as chemical bath. But elbow grease afterwards is still necessary.

Many new "rebuilders" often make the mistake of believing replacing is better than re-servicing and live with very troublesome results in tuning of their bike afterwards. The emulsion tubes and jets and all brass will come clean so long as its not corroded or damaged.

This is great advice, I never would have thought that the aftermarket parts would differ so much. I'll do the best I can to clean the originals up. I checked on them this morning and they are looking better.

edwardmorris · « **Reply #58 on:** October 23, 2015, 09:42:00 AM »

Not sure if you're talking about the needle jet and holder or simply the float valve/needle and seat. The latter, is probably better to replace and avoid leaks/overflows. These valves are matched to their seats and tend to leak due to wear. Even if you do wish to replace the needle jet, stick with all OE parts. I did replace all the brass on my K2 with new OE stuff and it all works well.

autotec · « **Reply #59 on:** October 23, 2015, 11:09:05 AM »

Quote from: edwardmorris on October 23, 2015, 09:42:00 AM

Not sure if you're talking about the needle jet and holder or simply the float valve/needle and seat. The latter, is probably better to replace and avoid leaks/overflows. These valves are matched to their seats and tend to leak due to wear. Even if you do wish to replace the needle jet, stick with all OE parts. I did replace all the brass on my K2 with new OE stuff and it all works well.

No, the float needle and seat will be changed. The needle jet and holder I'm going to try to reuse the original.

autotec · « **Reply #60 on:** October 23, 2015, 07:19:55 PM »

Well the first carb was pulled from the drink and everything looked great, so I decided to dunk the other three. Of course the very last jet I had to remove on the last carb, broke off inside of the body. I hope after a soak the piece left inside is easily extracted. We will see in the morning.

754 · « **Reply #61 on:** October 23, 2015, 07:24:59 PM »

Look like you are lucky to still have your thumbnail....yeeoowwwccchhh..

autotec · « **Reply #62 on:** October 23, 2015, 08:02:40 PM »

Quote from: 754 on October 23, 2015, 07:24:59 PM

Look like you are lucky to still have your thumbnail....yeeoowwwccchhh..

Yes I am, LOL. Tip of my thumb was cut off when I was 2 or so. Nail has grown that way since then. (38 now)

I do have a question though since I want to support any forum sponsors. Who do you buy your parts from?

Thanks, Justin

autotec · « **Reply #63 on:** October 23, 2015, 08:47:34 PM »

First round of parts ordered, out of many I bet. I want to start this bike before I tear it down, I just want to hear it run.

autotec · « **Reply #64 on:** October 24, 2015, 05:23:27 AM »

Quote from: calj737 on October 24, 2015, 03:40:53 AM

Quote from: autotec on October 23, 2015, 08:02:40 PM
I do have a question though since I want to support any forum sponsors. Who do you buy your parts from?
Depends entirely upon what you are buying. Honduran (Mark Parris) has his website with some electric system upgrades, swing arm rebuild services, and of course, his 750 Bible!

www.slingshot-cycles.com for brake lines and related components.

Godferrey for various items
Harisuluv for carb expertise and some hard to find replacement components
Noblehops for vapor blasting services
Powderman for powder coating expertise
Bill Benton for used, spares for anything Honda
APE for race/performance parts/services
Pamco for electronic igntion

And so on... I'm sure theres at least 50 more people who contribute and offer top class services, products and expertise that I'm forgetting. Best advice is to ask before you buy across the Internet. Someone will know what, where and why to use a Vendor or choose a product based upon experience and knowledge, not just price.

Excellent info, thank you.

edwardmorris · « **Reply #65 on:** October 25, 2015, 10:58:10 AM »

Quote from: autotec on October 23, 2015, 08:47:34 PM

First round of parts ordered, out of many I bet. I want to start this bike before I tear it down, I just want to hear it run.

If you haven't already, grab a copy of Mark's book. Basically essential reading if you're going to be tearing it down (in part or full). Just so happens there's a good promo running till 10/26

http://forums.sohc4.net/index.php/topic,65293.msg1742377.html#msg1742377

autotec · « **Reply #66 on:** October 25, 2015, 08:31:13 PM »

Quote from: edwardmorris on October 25, 2015, 10:58:10 AM

Quote from: autotec on October 23, 2015, 08:47:34 PM
First round of parts ordered, out of many I bet. I want to start this bike before I tear it down, I just want to hear it run.
If you haven't already, grab a copy of Mark's book. Basically essential reading if you're going to be tearing it down (in part or full). Just so happens there's a good promo running till 10/26

http://forums.sohc4.net/index.php/topic,65293.msg1742377.html#msg1742377

Thank you, just ordered the hard cover. Can't argue with 30% off.

Thanks, Justin

autotec · « **Reply #67 on:** October 25, 2015, 08:57:04 PM »

I had to take a break from the bike for a day or so to get some tile work done on the house to please my wife, but I was able to sneak in some work during that time.

Now I know there are probably better cleaners for the carbs, (like my 40 yr old 5 gallon pail of chem dip) I liked the result of the Pine-Sol. It left the original color on the bodies. But I don't think the solution was strong enough to get rid of the corrosion on the float pivot areas.

After hours of trying to free them up, I had to resort to cutting them off. Of the hundreds of carbs I've rebuilt, this was a first. I planned on replacing the floats anyway, and I didn't want to risk damaging the carb bodies. See pics below.

I also was able to extract the broken piece of the slow jet out of the #3 carb. Took some soaking with some PB Blaster, but it finally came out. See picture.

autotec · « **Reply #68 on:** October 29, 2015, 05:01:09 PM »

Some parts showed up today, so back out to the garage. I want to get the carbs back together as much as I can before parts end up missing. I have everything to put the fuel tank back together, and everything for the carbs except for the floats. I still need to order those.

Thanks, Justin

autotec · « **Reply #69 on:** November 02, 2015, 05:47:18 PM »

Just a little update, carbs are assembled minus the floats and 4 cotter pins. There were a few spots of corrosion I couldn't get rid of so there are a few dark spots on a few brackets, but I'm calling it done. Not 100% happy with the result, but it is what it is....

autotec · « **Reply #70 on:** November 05, 2015, 06:34:45 PM »

I actually took a couple of days off of work to work on the bike, but never got a chance to touch it. It's funny how that works. So tonight, I figured I would put a few hours aside to figure out why I didn't have spark. After a quick clean and re-gap of the points, I have great spark. Fixed, done. Looking at everyone's projects, I guess I was lucky to start with a clean bike.

The problem I'm having is I don't know what way to go with this bike. The more I clean and polish the chrome, the better it looks. All of the small pitting is coming out of the chrome and the aluminum is cleaning up. Call me crazy, but I'm even considering putting the sissy bar and luggage rack back on. I guess I'm just undecided at this point. Do I just clean and make it road worthy, or do a total nut/bolt restoration?

Stev-o · « **Reply #71 on:** November 05, 2015, 07:09:08 PM »

Do a "clean and ride" for now...then decide it it is worthy of a nut and bolt restore later.

I vote NO! for the sissybar and luggage rack.

mrbreeze · « **Reply #72 on:** November 05, 2015, 08:22:32 PM »

Sometimes you get a vehicle that you don't know much about so you ride it/ drive it....get to know it and go from there. These bikes are very bullet proof so I second Stevo's advice and just ride it. Fix little problems as they arise. Keep it in tune, don't let oil changes go for long periods. Clean it up as you go along. Add cosmetics to suit your needs.....make it yours. If you really feel the need to do anything major....consider buying another one so you have a rider and a project. I've owned my 750 for 15 years and it's a work in progress. Still kickin' myself in the a$$ for unloading my 2 project bikes but you do what you gotta do when the economy caves on you.

seanbarney41 · « **Reply #73 on:** November 05, 2015, 08:27:23 PM »

it's only original once

autotec · « **Reply #74 on:** November 05, 2015, 08:58:13 PM »

Thanks guys, I think I may have a game plan started. The frame is pretty scratched up, so that will have to be painted or coated. The engine is pretty clean, but there is a leak while it's sitting on it's side stand, so it's going to need seals and gaskets. The case is very nice, so I think I'll leave that alone. The cyl has some corrosion, so I think I'll clean that and try to leave the finish as natural as possible. Everything else, I'm going to try and clean to see where it takes me.

I did finally drain the oil and put a new oil filter in. I got about a quart out of the oil bag, and about 7 out of the crankcase. This worried me until I remembered my uncle telling me he would lube the cyl's every year. After 40 yrs, maybe it all added up? It all looked clean, so just maybe. We will see.

I still need to order the carb floats to see if it will start. I'll do that this week.

Thanks, Justin

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Author Topic: 1972 CB 750 restoration after a 40 year nap (Read 17330 times)