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My bike..
I bought this bike about mid-october last year.
It is a Honda CB250 k2, which makes it a 1971 model bike. I bought it with a near 0 knowledge of
motorcycles, i knew where the clutch, brakes throttle and gear selector were, i just didn't know
anything further.
In the time since then, i have done a lot of work on the bike, however it needs a little
more work before it is even roadworthy. Currently the work i have done on the bike thus far has
been in approximate order:
- Inspected the wiring loom, and replaced all the burnt out wiring (i wish i had a photo of
how it was like originally, it was pitiful.
- Degrease the bike (easier said than done, with all the grease that has caked up over the
decades), it still needs a final once over though..
- Strip carburettor's down and clean all the gunk out.
- Adjust the tappet's and the ignition timing, and generally give the bike a once over, still
isn't perfect, but it sounds nice.
- Adjust the clutch.
- The chain has been adjusted, I will replace it in a little while though.
- Replace the Mufflers as the old ones had the insides rot out with old age.
- The front brake pads were replaced, brake lines checked & bled.
- I swapped the speedo with a km/h model, i need to work out some minor details however.
- The brakelight frame was replaced as the old one rusted away somewhat.
- Replaced right hand switchblock with one from a couple yrs later, i now have a accessible killswitch
- got some headlight parts, now have a high beam indicator light on my headlamp.
Although it isn't *exactly* a motorcycle part, i passed the RTA learners bike course on the weekend,
meaning I only have to get the bike registered and do the L's written test (presumably i'll do it in the next month or so).
I have electrical schematics that came with the bike, unfortunately it is hard to read a schematic with about 40 wires and 1mm print.
So i have resized it and coloured the individual wires accordingly and put it online
The "to do" list.
Things that need to be done to get it roadworthy:
- The electrical's still need work, The charging cct seems broken, & the rear indicators aren't working.
- I need to scrub the bike down with a steel brush some more, the wheel's are a bit scratty.
Things i'd like to do to the bike but can't afford.
- Give the bike a respray
- Have the leather on the seat redone.
- rechrome the exhaust header & splashguards.
Mini Journal
7/2/03
This is what the electrics hidden by the headlamp currently look like, a evil mess i know,
but hell, it'll have to be sorted pretty darned soon, that's the next thing i'll be playing
with after i finish with the front brakes.
I've had to muck with the front brake control as it's sticking slightly, it seems good now
that i've taken it apart, now i need to bleed it again and get a tub of grease to get it all
lube'd up and so nothing will break/prematurely wear.
Also i have a spare speedo & rear indicator/brakelight set, they will go on at some point to
replace the current one. All i can say is, if you need any parts for almost any motorbike,
"Joes Spares" in Canberra are almost certainly sure to have whatever you need, and for each
thing you need, about a thousand bits you wont need.
10/02/03 I have found a source for almost everything i believe i need to get this puppy roadworthy, new
rear view mirror's, fron disc pads (i'll get the rear ones changed professionally once the bikes
roadworthy, cant be bothered with the excessive hassle. all i need now is a bucket of patience to
help me with tacking the sodding electrics. oh yeah, and in the "done" category, i passed the learners
Theory test for riding a motorbike, i can legally ride on the road, now watch the hell out y'all.
10/02/03 Today and yesterday were a hell of a lot of productive days, I spent the better part
of thirteen hours going over the electrical system with a very fine tooth comb, and checking any and
all indescrepancies from what was actually on my bike, compared to what was in the electrical schematic.
I also repositioned the rear indicators to their *correct* position of just aft of the shock absorbers, and
mounted directly on the spashguard, This took a lot of time as i had to drill out the bolts welded on the
splashguard (2-3 hours with a electric drill, i think i might benifit from a 240v drill). After i had mucked
about trying to resize the hole to suit the indicators (approx 15mm) with about a 12mm drill bit. It occured
to me to get a round
 
file, so down to auto-1 to get one i went. Now everything is in their "correct" spot,
and i can work on getting the minor "bugs" out of my bike, as i am 99% satisfied that it is roadworthy.
14/02/03 I have done a few little things today, but they were what i thought were the last of "things
to be done" for the bike. I got a new horn for the bike, it came in a pair, so does anyone need a car horn?
i have one spare. Next up was to make the speedo cable adjuster, two hose clamps and a peice of coke bottle
later, and i had the speedo cable attatched  (it doesnt look dodgy, just sounds it). I managed to drop the bike
because the stupid brakes were gripping the disc too much, i remedied this by undoing the bleed nipple on the
brakes, and compressing the brake to get the pad to release by about 1/2 a mm. I also wound the "grip" screw
for the other side out a little. it now rolls correctly with little risk of a droppie. As in the picture above,
i hooked the bike up next to my car with a pair of jumper cables, it starts and goes ok, but now i think i've
got myself a mangled battery, and it was brand new before *shrug*. Shit happens, looks like i need a new battery
too. I've also discovered that there is a bad earthing on my rear indicators, i also suspect that my blinker
relay is shot, that's another "must buy" item, so im close to the end of this saga, just not quite through the
door just yet. One last thing i also need to do is install the side view mirror's that i still have in their packaging on my floor.
17/02/03 I have attatched the digital speedometer to the bike and have confirmed that it works, it's only
problem is that it is a nightmare to configure it, and "once set" i leave it the hell alone.
In the top Picture,
the reed switch is the black device that is next to the brake line (and yes i used a 5 cent coin as a washer as
i couldn't find anything else to use. At the very bottom right of the image is a *VERY* strong magnet i took out
of a old hard disk drive, and it does the job extremely well, it's also hard to tell fron this picture, but the reed
switch is only 7mm away from my wheel rim.
 Now onto a part of my work that doesnt *QUITE* work. I figured out the other
day that the rectifier had gone open circuit and shorted out between earth & one of the a/c loops, this was sufficient
to cause that battery drain that i had experienced previously.
 I did a bit of research, and found that a "new" rectifier was the better part
of $140, a used one would be about $70, and i was theoretically able to make my own rectifier unit for about $40, I went
to dick smiths and bought a watertight aluminium box for $9, a heatsink for a further $9, and a rectifier rated at 1000
volts and more importantly 50 ampres for $19. I put it together, plugged it in, hopped on the bike, and rode around for
the first time!!!!!!!!!!!!!
The bike goes well, very well, i then discovered that for some reason, the charging cct wasnt charging. I have taken my
rectifier out, and double checked it, i have confirmed that the alternator is generating current (2 armatures are giving
200v each, one is giving 80v, but it's all good. I suspect it's either the rectifier cannot keep up with the high
switching rate required for this use (3 phases running at from 1500Hz -> 8000Hz), the wiring, or the regulator had bit
the big biscuit in the sky. Tomorrow i will do a bit of troubleshooting, wiring, regulator, then lasrly rectifier.
This is from where i sit. :-), unfortunately the speedo isnt straight
this isnt accidental on my part, but because i mixed and matched parts from another model, this is the only point i could
actually make this puppy fit.
20/02/03 - 23/02/03 I've been a busy boy, bought a new alternator, rotor for alternator, a new right hand headlight
switch block, this one includes a kill switch, which is freaking sweet as, a spare headlight assembly, etc.. cost me a bunch
of money, but it's worth it. I've swapped the switch block over, tidied the electricals. All that i have to do now is replace
the air filter foam (bought some from auto-pro today), get a mechanic to rattlegun of my old rotor, and away we go. You see my
current rotor is giving a low charge, and in order to fix that, i need to replace the rotor, and failing that, the alternator
stator, which i have a spare of "in case" that is needed. fix a slight electrical problem with the rear indicators, and then
i am set as can be, and i can go on to spending big money (i.e. registering the bike). It's just a matter of days now, damned
weekends, messing up my plans.
24/02/03 I have had a hectic two days, i had decided to talk to a mechanic i know, and ask to borrow his rattlegun
so that i could get the old rotor off the bike. We (myself, Sam & Ferris) got the bolt off, then we got to getting the rotor
off, and we realised that we didn't have the facilities to break the taper joint. So we put it all back together, and i rode
it home. You wouldn't believe it, but that wasted the better part of 2.5 hours, as all the bolts had aluminum oxide and other
corrosion holding 'em on tight.
25/02/03 Today i took my bike down to BMS Motorcycles in Botany, (376 Botany Rd, NSW, Ph: 02 9318 0008, they are a good bunch, so if
you need a hand, or a part, i highly recommend them.) and asked them to take a quick look at it. And lo and behold,
that freaking alternator problem I had before, had SOMEHOW fixed itself and was gone!!!!! Though the guys confirmed that
the rectifier wasn't holding the load and was loosing it's umph at higher revs. So when i got home, I put my d.i.y. rectifier
back on, and we were in business again, except for a leak that had developed from when i last opened the alternator cover. I also found
the neutral indicator wire hanging loose in that part of the motor, so it was a bit of a double whammy as well, now i can see when
im not in gear.
I emptied the sump of the oil of that unknown vintage from when i got the bike, and put in some Shell XL. After cleaning the
finger smears off the bike, i took it for a bit of a burl around the block, and everything seemed good, the engine seemed to
be charging, but i'll give it a good test tomorrow. I also figured out another bug in the bike tonight, the right hand cylinder
was randomly firing/not firing. I checked the High tension lead, and the end cap was very loose on the spark plug, a quick squeeze
with a pair of multigrips seems to have fixed the problem (the biggest symptom was the bike was sagging in power intermittently
when i rode it, sometimes the right cylinder would fire, giving a huge boost in umph, however this lasted a second or two, then
went away, leaving it stuttering along, a unfortunate side effect was that it'd often leave me struggling to get the bike to get
up to speed, as well as maintaining an acceptable speed. I guess i could put the summary of things at the moment is, "I'll
see how things go tomorrow!  ". I'm not gonna be praying for a miracle
but im going to sure as heck keep my fingers crossed that all the nightmares are behind me.
Oh yeah, i also fitted the new air filter foam today, looks pretty funky, the spray on oil for the foam made it a bright blue!.
26/02/03 - 28/02/03 My bike is on the road, the blue slip inspection went rather seamlessly, although it was a BIG
pain in the ass to find a place that would do a inspection "here and now", funny enough i got it done at the HQ for Taxi
Combined ServicesThe thing went well, aside from a note that it had a very minor engine oil seepage. not too bad however.
Yesterday i took the bikepapers for the NRMA and the RTA, I had a bitta fucking about with the RTA as the reciept i had
was a bit dicey by their standards, meh, but what are ya gonna do? But it works, and i think it works well. Ive racked
up about 100kms of riding in the past 72 hours, and consumed something like 5 litres of fuel, maximum.
As things stand, I'll leave this page as it is for anyone to look at if they want to. I'll update it with any minor/major
adventures i have mechanically with it.
Hope you had a fun read, I had fun putting it together, now i can have the fun of many miles of riding
Michael
oh yeah, the speedo is still munged, i'll fix that when i can be arsed.
Bike Specifications
DIMENSION
Overall length: 2090mm (82.3in)
Overall width: 775mm (30.5in)
Overall height: 1075mm (42.3in)
Wheel base: 1320mm (52 in)
Curb weight: 160kg (352.8ln)
FRAME
Suspension (F): Telescopic fork
Suspension (R): Swinging arm
Brakes: Internal expansion (Drum) (i would also like to point out that this is "stock",
however my bike has the front forks off a later model cb450, which provides it
with front disc brakes.
Fuel tank capacity: 12Lit. (3.2U.S. gal., 2.6Imp, gal.).
Trail: 85mm (3.35 in)
Caster: 63'
Tire size & pressure (F): 3.00-18 (4PR): 1.8kg/cm2 (25.6ln/in2)
Tire size & pressure (R): 3.25-18(4-PR)/3.50-18(4PR)
ENGINE
Cylinder layout: Twin, vertical side by side.
Valve arrangement: Over head camshaft
Bore and stroke: 56x50.6mm (2.205x1.992in)
Compression ratio: 9.5
Displacement: 249cc
Carburetor: KEIHIN CV Type
Number of Caruretor: 2
Oil Capacity: 2 lit. (2.1 U.S. Quart, 1.8 Imp, quart),
[for oil change 1.7lit (1.9U.S quart, 1.5 Imp quart)]
Lubrication: Forced pressure and wet sump.
Oil Strainer: Centrefugal & Screen mesh filter.
Reduction Ratio:
Primary: 3.714
Secondary: 2.375
Gear ratio
1st 2.353
2nd 1.636
3rd 1.269
4th 1.036
5th 0.900
Starting Method: Starting motor, kick starter
PERFORMANCE
Max. speed: 160km/h (100mph)
Max. torque: 2.14kg-m/9500rpm
Max. output: 30 PS/10,500rpm
Fuel consumption: 45km/lit. at 50km/h, (106mile/U.S. gal at 31mph), 127mile/Imp, gal. at 31mph)
Climbing ability: 20'
Min. turning circle: 4.2m
Braking distance 14.5m at 50kph, 47.6ft at 31mph)
ELECTRICAL
Ignition: Battery ignition
Spark Plug: NGK B-8ES
Headlight: 12V-35/25W
Stop/taillight: 12V-23/7W (1034)
Turn signal light: 12V10W
Battery: 12V-12AH YUASA type
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