The Humpty Bike - Putting it back together again

[kauai1800]

Aloha Guys,

OK well I've introduced myself and my project's now got a name - The Humpty Bike - for obvious reasons. (Plus it's my "chance to do the hump" ).

For me this will be fully 100% harder than anything I've ever tried to do working on bikes. I've never torn a motor apart other than for valve checks and tweaks. But I'm actually not tearing apart to fix something; I'm simply putting it all back together again and I've got a full service manual. It seems like a long road, but one I can follow. I want to extend my thanks and appreciation for your helpful comments. I love old bikes and I love seeing them run again.

The beautiful thing about the cheap $400 pricetag for Humpty is that I plan to use it as Honda intended - to learn how to repair and restore a DOHC engine. Kinda ironic considering I graduated High School the year this bike was built - 1981. But though intimidated, I am not afraid! If I can simply get the motor together and running this project will be worth every penny and every minute. If I get the bike all back together and running that will be the icing! If I can manage to get it titled and rolling on the street - that would be insane.

I've decided not to part it out unless I reach a point where a running bike is not a possibility.

My guiding principals:
• Not spend any more money than I have to to make it run and look ok
• Keep all original parts possible
• LEARN stuff
• Go slow and not screw up the motor
• Goal = running bike that is mainly original parts and stock paint, but not a perfect restoration

OK, so here we go.
I want to keep everything stock to make getting the engine running less of a headache.
My first question is this. I have a rusty but untouched factory 6-2 exhaust.
Here's a bad photo I took of one pipe. They both have no dents and no wear or thin spots; only lots of surface rust. My plan for these is to lightly sand off as much rust as possible and repaint them with high temperature black paint. If there's a thread about this I couldn't find it...everyone seems to have non-original pipes. Why is that?
I figure by painting them black they'll look decent and remain in good shape should they ever get rechromed in the future.
Does this sound like a good plan?

[NobleHops]

Hmmm. I wonder if those could be ceramic coated? Black exhaust is a matter of taste, but whichever color I don't think you'll find spray paint a durable finish on an exhaust. Ceramic coating is surprisingly cheap. Given that you have a solid core I would personally investigate that.

Search here for that - there are several references to good vendors. QC coatings comes to mind.

N.

[NobleHops]

Oh and sooner or later you're going to have to give us a look at that car. Maybe in another thread when you're not preoccupied with getting your project launched

N.

[kauai1800]

Oh and sooner or later you're going to have to give us a look at that car. Maybe in another thread when you're not preoccupied with getting your project launched

N.

Sure! I'll upload one soon.
I was going to make it a photo quiz to see if anyone could identify the car from just that small sliver. But my avatar name pretty much gives it away. It's a 1964 Volvo 1800S..I've done lots of work to keep it original and in cherry condition.

[Samelak]

I repainted my original pipes using high-temp for the header portion and satin black for the muffler. Looks good and only the header requires an occasional respray to cover rust stains coming through. I used a docto and a 100 grit disc to remove the chrome and prepare the surface.

[EMS]

I know you want to keep cost to a minimum and painting may be the most economic way to go. But...
Decent - not perfect - Prolink exhausts can be had rather inexpensively. 81 and 82 CBXes are being parted out all the time. Parts are on ebay. If it wasn't for the shipping to Hawaii...

[kauai1800]

Thanks for the good ideas. I hope you don't mind me taking you through this rebuild.

Yeah, shipping anything large to Hawaii costs a lot. Probably over $150 per pipe.
So I'm on my own.

And thanks for the idea of the ceramic coating Noblehops - I did some research and you're right, it's not as expensive as I would've thought. Cool stuff too. Sadly, no one around here does it. Cericoat (or whoever the main firm is) doesn't even have any dealers on Oahu, let alone Kauai. It's really rural here with only 55,000 residents.
But the ceramic coat idea got me the name of someone here who does some kind of rechrome-like procedure on pipes. I don't know exactly what that's gonna be - but I'll investigate.
If nothing else works out I'll do the VHT paint thing with the curing steps etc. This has worked ok for me on smaller projects. Even just the aluminum foil and marvel mystery oil trick should get off 70% of the rust - there's some pitting though. We'll see how it looks after some elbow grease. I used some MMO on the aluminum carb covers and some other parts to get off the white oxide and it worked pretty darned well.

In about an hour I go up to get the rest of the bike. One thing I hope to locate is the 6 'joint rings' that are the finned donuts that join the engine to the pipes. No sign of them in the parts bin.

Looks like I'm also getting an old moped as part of the deal. I guess this woman really wants this stuff gone.

[gak1047]

Before you have them coated or painted try you might want to try what I used.

I bought an 80 last year. The previous owner had removed the stock exhaust about a year after he purchased the bike. He stored them in a garage for about 30 years. When I bought the bike I purchased the exhaust as well. They looked to be in worse shape than the ones in your photo. I used Permatex Rust Disolver Gel and Turtle Wax Chrome Polish and Rust Remover to clean up my pipes. I bought both of these items at the local auto parts store. It took a lot of elbow grease but they came out pretty good and it was alot cheaper than a used set on ebay.

Good luck with the resto. I love when people buy these old bikes and bring them back to life. And I like the idea of leaving it stock. There are some fantastic custom 81's out there but I still like the stock look best.

[kauai1800]

I used Permatex Rust Disolver Gel and Turtle Wax Chrome Polish and Rust Remover to clean up my pipes. ...

Good luck with the resto. I love when people buy these old bikes and bring them back to life. And I like the idea of leaving it stock. There are some fantastic custom 81's out there but I still like the stock look best.

Thanks for this tip. I'll see what they've got at either NAPA or O'Reilly's...which are my only two choices.

I got the bike back home with no problems and it's now sitting in the driveway. Here it was before I cleaned it up at all sans tank and seat...a diamond in the rough!


I've wiped it down and hit all the hardware with wd40 to loosen it up. The seat and tank cleaned up pretty nice.
I brought the rest of the motor home too. I was easily able to turn the crank on the bottom end - so that's a very good thing.



Didn't find any exhaust joint rings, but I guess I'll be able to get these off eBay. I might also get one of those kits that have every CBX motor bolt so that I'll have what I need and all new. They are only $35 or so.

I think my earlier estimation of the bike's condition was optimistic. The fairing does have some small cosmetic damage (scratches and scuffs); the windscreen is very hazy and has a ding where a coconut hit it; small dents in tank; chain guard is rusty; wheels are good, but some light oxidation on the hubs. Seat and rear cowl is 100% perfect. Chain is really rusty -can this be saved somehow with a long soak in something? And I'll have to bone up on this air suspension stuff.

One fun side story. Just two days before I bought this bike off Craigslist, I was watching Jay Leno's Garage (I've watched almost all 150 videos..) and saw the episode about his CBX. You could tell Jay really likes the bike, being his first purchase and all. I had heard of the CBX before, but his video made me see how cool it was.
The Gods of Cycling must've been pleased - as 2 days later I saw the Craigslist ad only a few hours after it went online and sprung into action.

One last photo...this is a mock up of what I expect to end up with if all goes well...black pipes but otherwise pretty stock.

[steve murdoch icoa #5322]

In all the years i have been reading about bikes this is the first time i have ever seen the phrase..."has a ding from where a coconut hit it".

[bikeymikey748]

"Diamond in the rough"? Hey, wait a minute. Where have I seen that before?
You've your work cut out for yourself. I'm jealous as hell that you picked up the 'roller' and the boxes-o bits for so little
You've sure come to the right place, and just in time too.....now we've some entertainment to tide us through the cold winter months (though, dammit, I'm guessing that's not an issue in your neighbourhood ). I like how you're thinking your way through the rebuild......much, more please!
Coconut damage? Yup, that's a new one

[NobleHops]

BTW if there is something I can scare up for you from suppliers stateside and drop in a Priority Mail box, feel free to ask. Also, get in the habit of posting parts needed in that fourm. We're all pack rats and eventually can be coaxed into digging in to our spares. Now if you'll excuse me I'm headed into my garage to see about your exhaust collars.

N.

[EMS]

Somehow I remember that there was an ICOA member in Hawaii. Maybe Rick or Dave can help out. It seems he had an 81 and was taking it to the drag strip quite regularly. Don't recall his name and exact location, maybe he can be of help in the restore???

[CopperCollar]

Yeah another diamond in the rough! Good luck I say.

Having been through this myself you will have a very rewarding experience.

As to coconut damage, oh yeah. Those damn things can be heavy and they do leave some damage. I lived in Pearl City back in 75. I was stationed at the diving locker on the sub base.

Sure do miss it to, weather couldn't be beat. I am sure it's nothing like I remember though.

Keep cranking and I am sure she will be gorgeous and a hoot to ride.

Mike

[kauai1800]

LOL...Diamond in the Rough..guess that's a phrase that pops to mind for anyone seeing a cbx torn down to the frame, ain't that right bikeymikey?

I had been reading the thread with Kent's bike from last year and now I'll read the Diamond in the Rough Thread cover-to-cover (it's 17 pages long!). All this information is pure 100% gold and I can feel the love and willingness to help. I checked this forum before I pulled the trigger (even though it was only a few hours before I had to see/buy the bike...) and seeing this longtime community of CBXers willing to share their experience made it much easier to get so darn far in over my head. That's actually a value of a forum I hadn't considered before - that for a pre-noob it offers reassurance that help will be there.

And yeah, I guess maybe you guys are out riding a little less this time of year - which is very good news for me. I try to not discuss the weather here in Kauai on these forums because I'm looking for help, not outright hatred..lol! Basically it's nice here most days...


bikeymikey748 sez:
"You've sure come to the right place, and just in time too.....now we've some entertainment to tide us through the cold winter months"

Thanks for the offer of help - I'll be around a lot. You'll have to excuse me for having a few noob questions that are probably so basic that I can't find the answers here when I search. Like on a bicycle forum, there's no thread about "how do I balance this thing?"

So how does the stock air suspension work? Just the basics. I simply have never seen one in action. I'd like to keep it. I see the air valve on the steering head..I see a funky-looking cylinder under the seat that must be a mono-shock or air spring or something. The Pro-link I reckon. So you turn the bike on and it does what?? Rise up? Stiffen?

One thing to mention here at the onset is that I am NOT trying to make this bike perform all the way to its maximum level. I have seen what can be done with a cbx or a cbx custom. Crazy-cool and powerful machines. But that's not really my style.

I know they detuned the 81s, and the Prolink crossover exhaust isn't the best, the fairing might not make the bike handle as well as it can. That kind of stuff is ok for me. I'd rather keep it basically stock - that type of restorations is my favorite and imho maintains the value best..Where the restoration involves getting on the road again in a stock-ish form and that's it so you experience the bike as it came off the dealer floor.
On Kauai the maximum speed limit is 50 mph. The very longest stretch of straight road is 4 miles long. The TOTAL amount of main road - which is a 2 way hwy - is only 58 miles. So going really fast is not a priority. There's some twisties, but I have a Suzuki TU250x for those.

I love Japan, Japanese culture and vintage Japanese bikes. For me this bike's cool parts are it's engineering and old-school styling. The silver/black and orange paint is awesome. The huge headlight under the fairing looks killer. One nice thing is the front headlight acrylic is pristine...just a couple dead bugs to clean out. I bet the headlight even works. I need to get a battery soon. Gonna try the Mothers headlight restorer on the windscreen - see how far I get with that. Noticed it did not promise to remove coconut-induced damage It's actually a pretty common issue as the obvious place to park your cool car/bike/kevlar surfski/SUP/yourself is under a beautiful coconut tree. But those puppies can be lethal!

Probably should remove front fairing too but I am rapidly running out of space. Small garage have I.

OK here's another goofy noob question. What parts on a 1981 are made from magnesium or other exotic materials? I heard something about this..I love metallurgy/welding/exotic materials. I'd love to hear about anything cbx-related.

I've got one guy here on-island who is the tech at the Suzuki dealer; he might be willing to help me. I know he can help look over the cylinders, pistons, cams, head, etc and make sure they are up to snuff. Their shop can refinish the cylinders if needed. There's a few spots of light rust...very surface stuff. Otherwise no wear or scoring at all. I mean I guess you guys have seen these school bikes before...the parts are all new and the only issues stem from how they were stored.


There is also light surface rust on the con rods. I've read that cleaning this with a little phosphoric acid is a way to handle the rust. What you think? I'd really really rather not take the bottom end apart further and as I say, the crank spins like butter and there's still clean oil on the crank when you spin it.



Bottom end says made March 1981. Were these motors assembled on a standard line at Honda or did they have some kind of BMW M-Type-like "special line" for assembly?

As you can see, right now I have "big picture" questions...soon to be followed by endless small questions I'm sure. I will always strive to look for the answers myself before bugging you guys. There's a thread on the Do The Ton forum where basically they tell you to shut the %^$% up and just DO THE WORK and SEE what happens. I am fond of this philosophy to a point - but on such a sweet motor I do want to make sure I get it right.

Last question - these saddlebags, I don't want them. They have rusty hardware but otherwise are OK...perfect inside. Anyone here want them @ $100/pair + shipping or should I just sell them on eBay?



Same question about the entire OEM rear - the brackets (some surface rust but straight), the turn signals, taillight are all in great shape. I'd want the forum guys to have first dibs if these parts are hard to get - I just have no idea.