sebatron's CB125N build - I'm gonna call it "CB229S"

WARNING: EPIC READ

I've been in two minds about putting a build thread up. A few reasons come to mind - not least of which the amazing calibre of work done here, and a fear of not measuring up Really though, I didn't want to share until I had something worth sharing.

I hope you like it.

I've gotta play catchup for a good few months of building, so this will probably be episodic and pretty long.

First up, the backstory:
I'm a 25 year old Melburnian, and this is my 4th bike. First up was an ex250, then a k4 gsxr600, then a k4 zx-12r. I kept increasing bike size because i've got freakishly long legs. the zx12 was the most comfy bike i ever rode.
the time came where i had to sell it. i initially justified it because i was paying $16 a day in parking, and down here, motorbikes can legally park anywhere. it was cheaper to get the 12 on a loan, than pay parking.
naturally, a few months later i find myself having been made redundant. after a few months off the radar, i got into another job, but i suddenly have to drive a whole lot more, my expenses are covered and i dont pay my own parking. suddenly the 1200 is nearly useless. next thing i know, i stumble across dotheton.com and ideas run wild.
a brief background about me is that i studied electrical engineering out of high school, hated it, started studying mechanical engineering and loved it, but decided i didn't want to do it for a living given it gives me so much pleasure. biggest mistake of my life, but there you have it.
i end up needing the cash quick given so long without work, so i sold it for a paltry 6k. i wasn't happy, but needed to, and the guy took a bit of sympathy and threw me a CB125N to sweeten the deal. i start remembering what i'd seen here and elsewhere with cafe racers, and agreed to it having been given no info other than the bike hasn't run in 3 years, but nothing was wrong with it and i checked i would be able to register the frame (kinda like the titling thing you have up there...)
i took 2 photos, and i left. i thought back to when I was doing mechnical engineering, and transplanted a CA18DET into a Datsun 1600. caged it myself, upgraded to hilux 4pots and exracted 170kW at the rear wheels. i figure a 125cc honda could be nothing but a cakewalk in comparison, and i haven't been wrong about that yet.
i loaded the bike onto the trailer, and took it home:


we got it home, and started stripping it.


at this point, we get to thinking there isn't much to lose for trying to get it running. there's fuel in the tank, no oil leaks that we can see, but the batterys dead. kept cranking the shit out of the kickstarter, but amazingly got it working without so much as pulling a plug. mind you, took about 35 kicks to get it going.
Video you ask? Right here: http://img138.imageshack.us/img138/4396/dscn1299.mp4 (might need to put it into quicktime)

So what comes when you've gotten the bike running, but it's half missing? What do you think?! You go for a ride around the block, and I did just that.
Mind you I did that after I removed the footpegs, and all the indicators, instruments are lighting are just hanging off. went 25m to the nearest roundabout and brought it home.
Between myself and my fiancee, we got it down to the frame within 4 hours. Got pretty sore - damned seized bolts! the exhaust was the worst.

The next few weekends were spent trying to restore the old wheels. This was as far as we got (well, we did strip the wheels and try to restore pieces individually):

Not good enough, really. Bit the bullet and ordered spokes from thailand for a CB100. Actually got the wrong set initially (having not realised some cb100's came with 18" rear, and not all had a MECHANICAL DISC front brake.) but quickly exchanged it so it was peachy.
At this point, I'm thinking about a colourscheme, and for some stupid penis reason i decide i want everything either polsihed to a mirror finish, or fire engine RED. tastes change as time goes on, and i really didn't want to spend 3 weeks polishing a mild steel tank so the scheme got a little flexible, but it lives on.
i plan my rearsets, but not very well. got some universal rearsets and get to work with a grinder. got them to a mirror finish actually:

and i make some really shit brackets to attach the polished alloy bits to teh swingarm bolt, and centrestand holes. decided i'd shed that 10kg centrestand, so i made up some tube spacers to bring the centrestand holes in line with the kcikstand bolt.

content this will work, i start stripping the frame.

worked all the rusty bits off, cut off the unecessary tabs, and hit it with the etch primer.
by now i've decided i want red rims too. got the lovelylady to wirewheel the rims and rough up the chrome as much as possible, then shot it:


at this point, i'm realising how dodgy i'm being with this. from the rearsets to the etching. the fact i've never sprayed anything in my life hasn't put me off at this point. of course, given the $0 budget, i use what's around. dad has a airless house sprayer with a nozzle suitable for oil based paints.
i go absolutely ballistic with the 2pak and nearly kill myself with the fumes.


inexperience kicks in and i don't realise i need toget to buffing it pretty quickly. i just don't have time to put into the bike because of what was happening in my life at the time.
this is a wake up call for me. i'm rushing this project and losing all quality control in the process.
faced with being stuck with a non-glossy red finish, i shut down and put this on the back burner.
but my dad comes along and he's a gun. masters degree in mechanical engineering that australia wouldn't recognise when they immigrated to australia in the 80s.
he quietly (from my ma) gets the lot powdercoated, and i breath a sign of relief. of course, the crap labor ended up with orange peel bits in some spots, and didn't bother protectecing the threaded bolts or boltholes. still, it was cheap. i let my rage subside and just get on with it.

around this time i've managed to polish my fork legs and top triple (well, wirewheeled the triple).
From:
To:
excuse the shit photos, but that there is a mirror finish.
so i put it all together, and take a seat

now i'm getting somewhere, i see the rearsets are just done fuckin poorly.

by some fluke, the spacing i'd chosen happens to line up with the distance between the swingarm and centrestand. i wonder if i flip them, if they'll fit? sure enough, shorten those spacers and...


now really am cooking with gas.
more to follow, probably tomorrow!

alright, i don't wanna leave this on a low, so here's a bit of a fast forward. i'll backfill tomorrow!

I'll be watchin this one for sure. Looks good man

i won't bother posting up images of changing fork seals and bearings and things like that because it'd just be boring, so i'll continue and no doubt gloss over heaps.
forgot to mention, the passenger footpegs were deleted, clipons purchased, new spokes, i laced and trued the wheels myself.
so not much happened for a while.
i was scratching my head for a while trying to figure out going 12v on this bike, so i could run a smaller battery, whatever bulbs i want etc. the cb125n is actually an even more crippled version of the cb125s, sold between 79 and 82 as a budget version. yeah... a cheaper version of an existing cheap bike. get this: 4 gears. points. 6v. no voltage regulator.
i scored an XL125 motor - apparently a 6spd version - for only $60 on ebay. better still, it has compression and less wear on the camshaft journals than the cb125n motor. when i picked up the bike, they threw in a bunch of parts including a more or less complete motor.
so i start drawing up plans. i'm thinking theres no way it'll tow me on the bike, let alone a pillion. the bike will end up belonging to the mrs, but she needs to get into it first. riding shotgun will aid that endeavour.
so i look into it. i'm quoted $250-400 just to resleeve my barrel. $60 for an engine bolt set (cause those original honda ones will definitely have seized). $30 for a gasket set. a few hundred for xr200 or xl185 parts, and as little as $700 for a running motor, less wiring.
no matter what i do if i change anything on the motor, it's gonna cost an arm and a leg.
one uncharacteristically helpful machinist who does these motors here, asks if i'm doing it up for bucket racing. i said i'd thought about it, but doubted i'd pursue. i'd thought about putting a chinese motor in, but thought i'd have issues registering it.
this machinst says quite plainly that's bullshit, and our transport authority don't care as long as the VIN or frame number is clear and there is a motor number, regardless of what that number is. idea? can i get a brand new crate motor, with CDI, and at least a handle more horses for the same price or less than fixing up this shitbucket motor with a history of poor head longevity?
i lucked out. a guy comes along wanting whatever i have from my piece-motor because he IS involved in bucket racing and requires clean numbers. what does he have in exchange? turns out he works at a chinese dirt bike importer. i talk him into giving me a brand spanking new "250cc OHC honda-based vertical single cylinder air cooled motor". having read between those lines before, i catch on and realise it's actually the zongshen zs167fmm - it's actually an OHV motor, with a 67x65mm bore/stroke. that's 229cc peoples, not 2-fiddy!
but i digress. i got the motor with an exhaust, less carbs and all wiring. these things are easy to source here. the exhaust doesn't clear the frame rails, but it won't be the first exhaust i've ever done so i'm going to tackle it in the next few weeks.


ANYWAY.
like i said, not much happened for a while.
until last week. this trade went through, and the motor arrives tuesday. tuesday happens to be the day i picked up my new tyres.



the weekend FINALLY comes around and i get down to my parents' place for work on the bike. my partner's dead keen to get the motor in, and finally get an indication of whatit'll look like when finished. in other words, she wants to see her wheels.
my mind flashes back to that first night we had the bike, and spending a solid 45 minutes freeing the old motor. i remember powder has gone on, and those few mm is gonna make this that much more difficult. smome careful filing, and literally 2.5 hours later, my father, fiancee and I managed o shoehorn the motor in:

one may notice the utter lack of clearance above the head cover. ther's actually maybe 3mm in it. the ugly frame welds, irregular as they are, manage to go between the fins and have enough clearance to ease my mind. powder can handle 300 odd degrees. if things ever got that warm, i'd have other things to worry about like my nuts and the fuel itself.


i did end up grinding away at the fins a little. i wanted at least 3/8ths of an inch clearance, and i got it with plenty of meat to spare.
i will end up roughing up the motor before the bikes' "done" - i'm gonna file down the fin edges and do something drastic about the side covers, but i want to make sure it's going to run properly before i do anymore butchering. parts are cheap for this motor, literally $180 (australian) for a complete head. but that doesn't mean i want to go and buy another complete motor.
saturday continues, i bolt on the kickstarter and am amazed it clears my rearsets.

anyway, logically we finish up the wheels. having the two of us working on things means we got the front brake caliper rebuilt and painted, cut down and ground the original honda side stand/footbar mount attached to the bottom of the motor, less footpegs + filler + paint. there was some damned funky 30 year old water inside that tube. gross.
i didn't take any photos of that part at all, but i wish i had. i'm pretty happy with the side stand from te old motor being adapted to the new.


having greased all the bearings and both axles, i get encouraged to "roll it out, get the grease moving around!" - i haven't sat on this bike for literally 4 months.
the new rearsets hold my weight without flexing. the bike rolls true, and is smooth as hell. yeah, i got excited.

and one with the old tank, as yet untouched:

that tank. god damn. ugly as sin. i so badly wanted to go a polished alloy tank, but this bike has literally cost me less than 300 in parts so far.
i managed to get 1 photo, where the tank didn't give me nausea. it actually looks kinda neat here:

and that was saturday over. up at 6, down at 7. an amazingly productive day though, i'm sure you'd agree.

sunday comes, i can't sleep to save myself. i get up at 7 and get into the tank.
i'd always intended to remove the tabs that held the old side covers on. i'd decided i'd polish the tank with a "best effort" within a days worth of sunshine. being mild steel, and being i only get out there on weekends, i wanted to get it lacquered before i left.
so i (permanently) removed the ugly lid that covers the fuel cap, cleaned up the fuel cap a bit and got out the paintstripper:

i loved it.

next up, de-tabbing the tank. had to rinse the tank properly (still had fuel in it!), so did that and got on my way.
this is as good a time as any to do the token beer-and-tools-with-bike photo :

next up, took it to 240 grit, then 400, 600, 1200, 1500 and 2000. having polished my fork legs, which were alloy, i knew polishing the tank would be a fools errand given how much harder mild steel is against alu. 2000 grit finish - every step was done in both directions with wd40 to lubricate. i'm still sore, and that ended 52 hours ago. haha.

by the time i was done, the sun was down and the shots got progressively worse rather than better due to the lack of natural light.


and that's where it stands now. this weekend i'm taking to the exhaust, fitting the headlight (making a black stoneguard, time permitting) and making up my electronics trays for my CDI (thats right, fuck you 80s honda points!), 12v light relay, reg/rect, 12v led flasher, etc. might crunch some numbers for what kinda power i'll need from the batteries.
maybe, just maybe, i'll get onto the seat

Holy crap, that is the beefiest damned sissy bar and luggage rack I've ever seen.



I've carried a 12 pack of beer back from the store on my buddies CB350 with a luggage rack but you could fit a whole keg on that bad boy. It almost looks home built.

nah it's an authentic GEARSACC, vintage unknown - there was some very dodgy galvanised steel bits holding it on.
true though, i reckon i could fit a keg on it. i've still got that rack, nfi what i'll do with it. might incorporate it into something else.

alright, i need some help. i'm trying to figure out a safe method of linking the pedal to the rear brake.
this photo shows the standard brake rod:

it's the silver rod between the (red) swingarm and (red) brake arm.
if i have it running with the lever on the underside as it is now, that arm is gonna rub. plus, it doesn't run straight. is there anythign "wrong" with having the lever on the top side of the drum?
i've tried to work out using a brake cable from another bike (cb360?) but information isn't forthcoming. i'm going to need a cable with adjustable tension.

if i work out a pulley system so that the brake is pulled linear... would balustrading cable/ends work? sounds crazy i know, but i just saw some outside and i think it might be the ticket.
thoughts?
i'm still going to need to figure out a brake switch for the rear too :/

Here's how I worked out my brake rod issue. I bought some 1/4" steel rod, bent it with a torch and threaded both ends with a 6mm die so I could use my stock adjusting nut at the back. I still need to weld a washer to act as the stop for the spring in front of the drum lever and maybe paint it.

i like it, i like it a lot. off to the hardware store haha.

The yoke attachment at the pedal was SAE thread but I sent the 6mm tap through it a couple of times and it threaded on nicely afteer that. I may just paint my brake rod black since I clearly need to paint the muffler.



I figure it will just blend right in after that. I also plan on wrapping the pipes in black header wrap.

same! but i've seen titanium wrap for only a few dollars more so i might consider that instead (just to be different)
i'm sticking my exhaust under the motor though, with the outlet pointing out the side. just gotta make sure i don't singe my calves or feet
probably just going to use a straight pipe, but i'll make a meaty baffle. i'll cover the end with an automotive bolt-on muffler tip with a bend.

Geez this is shaping up to be an awesome build! And yeah theres nothing wrong with running the rod up top - its how my Kwaka 100 has it stock. Only thing to watch out for is that you have the lever pulling the right way. My setup isn't fussed about pulling either way, but others may be.

Cheers - boingk

nah, it looks like it'd work either way. the drums are actuated by a rotating flared pin, and would work either way. i was just wondering if there's something i don't know about that suggests itd be a poor idea.

alright, i'll try to get the rearsets attached this weekend.
interestingly, the gear shifter on the new motor has about an inch of offset to clear what looks like the oil filter housing (could be starter, wasn't that interested at the time) whereas the old motor didn't. not sure which i'll end up using.

thanks for the kind words guys, encouragement definitely motivates

Glad you are getting this thing up on the pages man. You and I are gonna become friends over these mini cruisers, I can tell! As you know I'm starting a CL100 build as we speak. Learned loads from you already man. Keep up the killer work!

i was just rereading the thread and realized that you are down under!!! what is shipping to the states cost from down there? its gotta be ridiculous no? but my floats do leak and i could use some spares, but the good news is bowl clean jets clear slide free and smooth needle wiped shiny and i thought i was missing the idle screw but some joker forced it in a blank spot on the carb body so i moved it back and now if i can tin braze my floats i may be good to go in the carb dept, plus that site you linked had a kick arm for like 6 dollars i think ill be getting a package from thailand soon.

anyway the alum tank looks great like that i hope you can find a polishing solution or a good clear coat.
mine is about half for my girlfriend to learn how t ride on and half for commuting with my skoolie (school bus based RV)

yeah i'm way way south of the border. heh.
shipping isn't too drastic from here, but yeah, if you're after a part, smaller is better
so yesterday was spent dicking around with the rearset. i took a page out of noahdog's book.
though for the spring stop, i just got an M6 nut and tacked it on
also fitted headlight. had to shim it because brackets small enough seem hard to come by and i'm getting itchy feet - for the most part, i'd rather not obsess over something as insignificant as headlight mounting, when i could do something more useful like make up an exhaust:


more to come in good time!