Author Topic: KZ 250 C "Blueberry"  (Read 4281 times)

Offline dray

  • Posts: 26
KZ 250 C "Blueberry"
« on: Dec 04, 2017, 11:22:56 »
Seasons greetings to you all.
I've been working to restore and custom a 1983 KZ 250 C.
This is my first full top to bottom project and has so far provided me with hair pulling challenges (due to my lack of experience) and satisfying outcomes.
I'll make notes of everything I can remember as well as the cost of parts I bought for it. I wont mention where, other than to say I do 90% shopping online.

The bike itself is a bit of an uncommon release. the KZ250 LTD, A, B and D all seem more popular.
What struck me as odd was that the A and B were twins with more ponies, the C was installed with a single and a downgrade in power!
I guess it was a corporate dollar decision.
Either way it's a fun little bike on par with an SR250 of the same year.

I picked this one up for $450 with delivery.

Previous owner told me he bought it from some rich bloke who used it to ride around his country property.
Looking at it's history it had a repaint and an engine rebuild back early 2000's.
Since then it was left to rot in the rain. Rust everywhere!

Mechanically it seemed fine but the carbs needed a good cleaning and battery to be replaced and it had trouble turning over.
Inspecting the battery I could see it wasn't holding charge and had low water/acid levels. Rather than mess around trying to fill up and charge I bought a replacement.
This did not fix the weak turn over.

Out came the starter motor, a Mitsuba SM 223c,  full of greased mud. Brushes worn away.
I bought what I thought would be the right build kit to replace internals but BEWARE, make sure everything specifically includes the kz250 C <--
the other versions can and do use different parts e.g brake pads, starter motor, sprockets, carburetors, gaskets etc. I'm sure a lot of you already know this.
I ended up cannibalising the starter motor build kit for the brushes as a temporary fix. I'll probably just buy a replacement starter motor as the price difference doesn't seem much different.
Once I reinstalled the SM, it turned over like magic.

Carburetor is a Keihin PW26. gave it a real good scrub. pilot jet was 42, main was 105.
On discussion with the good people at Retro Moto (local moto shop) I kept the pilot as is and main jet ungraded to 120.
Air box and stock flare exhaust has been tossed aside, pod filter and short exhaust installed.

For some reason (probably i shorted something) during all my tinkering I lost spark.
Inspecting the ignition coil showed (surprise) massive corosion.
I replaced the coil and spark returned.
So at this point I had enough of the rust and there were a few electrical issues with indicators and lights that I wanted to tackle.

With the rust I wiped, sanded, wire-wheeled and grinded away at the rust but something things were corroded through so I set up and electrolyte bath and started treating various parts that seemed pretty far gone. These mostly sat overnight or in 8 - 12 hour sessions. I made sure to use only mild steel and galvanised steel, no stainless or chromed. Speaking of galvanised, I did a bit of zinc electroplating however i wasn't pleased with the results, as i skipped on sugar, the zinc was granulated. I think molten zinc would produce a better bond.
Forks, fenders, handle bar, brake pedal were treated along with smaller items were de-rusted. Nuts and bolts got soaked in white vinegar.
Sadly, the front forks are heavily scarred and pitted from the rust build up. I have yet to decide whether to get them hard chromed or find a replacement. Seems they will hold for now.

« Last Edit: Dec 05, 2017, 10:05:33 by dray »

Offline canyoncarver

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  • 'hacking is learning'
Re: KZ 250 C "Blueberry"
« Reply #1 on: Dec 04, 2017, 11:44:38 »
Welcome to DTT.  Fun little bike.  Were you talking about Jr. at Retro Moto?   
73' The Commando
YZF750/1000R The Fly
KZ 750 Twin
ZRX 1100
KZ400 The Rabbit
KLR650, 69' Norton P11 Ranger, a 65' Atlas, a 60' BSA scrambler, 93" shovelhead chop, an 86' FXR, and an F9 Bighorn
more YZF750R's, more KZ's, a Zephyr750...and the ever unfinished 75' CB550 cafe.

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #2 on: Dec 04, 2017, 12:14:57 »
Welcome to DTT.  Fun little bike.  Were you talking about Jr. at Retro Moto?   
glad to be here! Well I'm in Perth, Western Australia so the guys I know are Scott and Paul. Interesting to know there's another Retro Moto out there!
Any advice on how to upload photos here? I'm  trying the > img][/img< thing but that's a no show.

Story continues ...
The electrics! Globes burnt out, wires shorting, connectors crumbling, more clean up required! I discretely removed the old lollypop indicators and giant rear brake light in favour of some LEDs. Front light to remain incandescent though replaced with something not quite so big.
I spent 4 hours trying to sort out the indicators, problem was the rear lights would light up and the front lights would flash together. I discussed with some friends who suggested resistors. In the end I smashed apart the indicator connector and reversed the polarity, voila!
Satisfied that I had spark, compression, idle and electrics it was time to pull the bike completely apart and paint.
« Last Edit: Dec 04, 2017, 12:18:31 by dray »

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #3 on: Dec 04, 2017, 12:29:18 »
I built a spraybooth and bake house for painting and drying, " bakehouse" is a loose term as i'm trying to harness the power of the sun to generate heat haha!
Given the amount of de-rusting I had to do on the bike I was a bit traumatised so I went straight for the super etch primer and covered eeeeverything.

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #4 on: Dec 04, 2017, 12:32:54 »
you can see in the above photo I knocked up a seat tray to house the electrics. A bit of CAD design came into play to get the contours of the box to line up with the frame.

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #5 on: Dec 04, 2017, 12:38:06 »
With more discussions with the guys at RM, I was told painting the engine is ultimately down to aesthetics. I like my science though and I decided on black for the crankcase to warm up the oil and silver for the head as the whole thing is designed to dissipate heat.

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #6 on: Dec 04, 2017, 12:45:10 »
And now here I am, engine remounted. Still a list of things to do.
Big jobs -
I need to modify the electrics to fit with the seat tray and adopt the new handle bar switches and lights.
Paint the fenders, mud guard and tank with 2 pack.
Fit new tires.
Small jobs - adjust mounting of tail light to rear fender.
Tune carb.
And something else, always something.

Offline teazer

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Re: KZ 250 C "Blueberry"
« Reply #7 on: Dec 04, 2017, 13:52:59 »
In the final analysis, the color won't make a huge difference, but black dissipates (or absorbs) heat better than light colors so it is used for barrels and heads to keep them cool.  Some like to paint crankcases black to help keep the oil cool too. Matt is better than gloss for heat transfer and a thin coat of paint is better than thick.  Thick paint acts as a an insulation layer.

On most bikes it doesn't make a whole lot of difference though, unless things are marginal. Keep having fun,  That's what this is all about.

Offline orrible-64

  • Posts: 713
Re: KZ 250 C &quot;Blueberry&quot;
« Reply #8 on: Dec 05, 2017, 08:06:50 »

One from the vault

Sent from my iPhone using Tapatalk

Offline dray

  • Posts: 26
Re: KZ 250 C "Blueberry"
« Reply #9 on: Dec 05, 2017, 10:03:34 »
I'm drooling at that tank! Pure eye candy!
The LTD is a real sign of the times with the Bosozoku lane split handle bars. slight differences in the crank case and looks like a smaller front drum brake.