My New Project: 1981 Honda CBX "school bike" - 6 cylinders of Go-power

kauai1800

kauai1800

New Member
Got thrown in the deep end last month.
Found a 1981 Honda CBX "school bike" on Craigslist for $400. It was actually $250 for the motor and $150 for the frame and a bunch of NOS parts. I could've parted it out and made some $$ (the OEM exhaust, carbs and NOS bodywork that came with it are worth at least $2K) but I've decided to make it live. It's never been on the road as it was meant to be used for vocational training...so all the bits are basically new...4 miles on the odometer - probably from being pushed.
Unfortunately some of the bits were left in the open air and need some love to work again. But it's "all there" and is cleaning up pretty nice.

The CBX is a 6-cylinder, 6-carb, 24-valve DOHC bike that makes 105 HP from 1049cc; they were the first official "sport bike" capable of making 100HP/liter; made from 1979 til 1982.
I've never actually seen one running, but with some help from some CBX guys on the forums we're gonna get the motor assembled (it's in pieces), then the rest of the bike.
Unlike the other bikes I've owned, once on the road this one will do the ton no worries. Top speed should be about 145. ;D
I'm excited because the bike will be true to the idea of being really fast and loud - but built for as cheap as possible. The goal is to keep the entire budget under $1000 even with new Avon tires. Might be a little more than this but under $1200 seems possible.
I'll post some pics once it starts to look like a bike again.
 
Saaaawwwwweeeeeet. I love the CBX.

They sound awsome with six into six megga's on them.:D They sound like a bunch of angels singing. :D
 
I've always wanted a CBX. I hear they're a tuning nightmare but man they sound so sweet..... CBX V12 anyone?
 

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I love my CBX
Hate to burst your bubble but $1000 is going to be very tight. These bikes have expensive parts and lots of them....

Watch out when dealing with a school bike. I dont think any of them actually had titles so that might be something to look into. Yes the body work is normally nice, but the mechanicals have either suffered from years of sitting, or years of kids "learning" on them

The factory manual is around for download and helps a ton.
 
RustyStuff said:
Now thats just exessive/stupid. ???
Click to expand...

Excessive.. Stupid... and awesome. Can you imagine the heat coming off that thing? If it tipped over you'd never be able to pick it up! ;D

http://www.motorcyclespecs.co.za/model/Custom%20Bikes/honda_v12_cbx_by_andreas_georgea.htm

There's some engineering greatness in that motor.

Seriously though, I want a CBX before I die.
 
It may sound stupid but what kind of school teaches you to ride on a freakin cbx? I like it ;-)
 
Back in the early '80's Honda donated a bunch of CBX's and Turbo CX500's to schools for shop class, so kids could learn to work on them. Not ride them. "School Bikes" are sought after these days because they're low mileage "buried treasure". One was featured in Motorcycle Classics magazine not too long ago...

http://www.motorcycleclassics.com/motorcycle-reviews/1981-honda-cbx.aspx
 
Redbird said:
Back in the early '80's Honda donated a bunch of CBX's and Turbo CX500's to schools for shop class, so kids could learn to work on them. Not ride them. "School Bikes" are sought after these days because they're low mileage "buried treasure". One was featured in Motorcycle Classics magazine not too long ago...

http://www.motorcycleclassics.com/motorcycle-reviews/1981-honda-cbx.aspx
Click to expand...


I was telling my dad about this today, my dad was at MMI in the late 80's/early 90's, they had a ton of CBX's, honda gave them away when they couldent sell them.After the school bikes were no longer needed, the schools were suppost to destroy them, because the Gov/Manufactuer felt they would no longer be safe.

He says most of them probably wouldent run, because of how much wear and tear they got being torn down by every student. And that this bike probably will have to be torn down and checked over/rebuilt, before it is even started.
 
In my experience th body work and other bits like that are prized form a school bike as they are often almost NOS.
However th mechanicals are more thn just suspect. Few bikes were school bikes and never touched so they get treated differently.
Also like I said there is a title issue. Now in some states that isn't hard to fix, others the bike can never be put on the road.

Assembling any bike for a box of parts is hard, a cbx is crazy. Might want to rethink it, part it out use th money to buy a whole one. They are not aw rare as one might think.
 
surffly said:
In my experience th body work and other bits like that are prized form a school bike as they are often almost NOS.
However th mechanicals are more thn just suspect. Few bikes were school bikes and never touched so they get treated differently.
Also like I said there is a title issue. Now in some states that isn't hard to fix, others the bike can never be put on the road.

Assembling any bike for a box of parts is hard, a cbx is crazy. Might want to rethink it, part it out use th money to buy a whole one. They are not aw rare as one might think.
Click to expand...

Aloha Guys-
Rustystuff - that's cool about your dad.
Redbird - thanks for that link - I had forgetten about that!
Surffly - you make some very good points and you are absolutely right about it being crazy - but I'm gonna do it anyway. And if you really want crazy, this will be my very first engine build ever...a friggin' CBX.
The bike did come with lots of NOS bodywork and the original Sankei 6-into-2 exhaust (though a bit rusty). I'm sure I could sell the carbs, exhaust, the NOS parts, the NOS bodywork and seat and make at least half of what a running CBX would cost.

But I'm not going to do that and it's not as hopeless as it sounds.

Here's the plan..a guy from the CBX forum who lives in Sydney is visiting Kauai for 3 days later this month and he's volunteered to give up a good chunk of his vacation time to help me get the motor running. Which is phenomenal. He's built up 2 CBXs before and having him here is all the confidence boost I need. We are going to make this bike run...and we've got 3 days to do it. ???
I don't want to part out this bike before it's even had a chance to run.

As for the condition of the bike and the parts. I too have heard many horror stories about the School Bikes, but based on how very few tool marks there are on the engine, I can say for sure this motor was not repeatedly broken down and rebuilt. Many bolts and screws have zero marks - the paint marks on the carbs have never been broken and even under high magnification (I'm a watchmaker by trade) many bolts are un-touched. The cylinder bores and heads look un-run and the carbs are very clean. My guess is that it might've even scared the instructor as the CBX's reputation was daunting in 1981...to me it looks more like they used it to show how a DOHC motor functions rather than being built up and taken down repeatedly.

It is true that the bike has sat in pieces and that is never good. The crank was open for years in the back of a shed for example. But we're going to open it and have a look...make sure it's clean and shiny (all indications thus far are it is...). We've already gone through all the parts and are making sure we have all the bits we'll need to do this rebuild in 2 days. Might be a little stressful! We are going to go through the head and replace all the valve stem seals as well as carefully clean and check the 6 Keihin carbs.

If we get the motor running, then the rest should be easier. Again, a kind CBXer from the forum *donated* 3x free brake rotors and another gave me 6x finned exhaust collars. Wow. The forum guys really want to see this bike run rather than parted out like most school bikes are.

I'm philosophical about this build...it came out of nowhere.....it cost almost nothing...the parts are there...the help I've gotten is unbelievable, and it's as if this bike has come to me like a stray dog and asked to live again.
Let's do it! 8)
 
Good for you!! Git er done!! 8)

When my buddy Pipewelder and I were down at Mid-Ohio last July, we met a fellow at the Motel 6 in Mansfield where we were all staying. He's a CBX Guru from the Cleveland area I believe (my memory isn't what it once was... sorry!). He had 3 of them there with him, one of which was for sale. He told us a story about how he rescued several "school bikes" and built some really cool custom CBX's outta them, including one that he had there that weekend.

He also mentioned the difficulty in getting a title for one of these frames. I don't believe he did.

He also mentioned how one of the engines had been horribly miss-assembled. It needed to be completely torn down and re-assembled.

Still, they are an interesting piece of Honda history and worth saving if you can. 8) Good luck! :D
 
The one thing that I might not have made clear is that the motor is already pretty much torn down. It came in pieces, bins and boxes. Head, cylinders, crank, and valve cover all apart and have been for some time. The frame is a roller.
So it's not a mystery - we can see everything and it looks OK..in fact the bike looks like it's never run. It came with all NOS rings, gaskets, intake boots, airbox boots - in boxes straight from Honda and 1981. The biggest concern is the crank and the plan is to break it open, examine the crankshaft and bearings - and pray it looks good.

I'm aware of the title concerns - but not worried about that at the moment...

And yeah Neevo...just look at that monster! The first iteration of this bike will be less extreme, but who knows what it might morph into?
 
The CBX guys have been great.
Glad to see it will be going back together, just was more a word of warning as so many guys bite off more then they can chew.

Check the cam tensioners as they are NLA. Luis in FL has the market cornered on cbx parts and charges for that....
 
Aloha surffly - I hadn't realized you had a CBX build of your own until I saw your project thread. Our bikes are almost identical as you know. What was the outcome? It sounded like you were having tons of problems with the carbs - did you get it get on the road yet? I really hope so...

And yes, I've been getting parts from Louis and lots of helpful advice like yours. I think I'll start a thread here on DTT as well because I think folks here "get" the CBX - and anyone who's never heard of one needs to. Cheers.
 
My cbx is almost done.
Carbs are a pain.
Few hundred just in parts. Looking back at it I should have just paid the grand to have them rebuilt
 
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