KZ 250 C "Blueberry"

dray

New Member
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.
Untitled.jpg

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!
20170912_110527.jpg

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.
20171005_155736.jpg

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.

20170912_110527.jpg

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.
21741693_10154837860038639_1947077549_n.jpg

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.

20171116_210339.jpg

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.
20171021_192906.jpg
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    204.4 KB · Views: 323
  • 20170912_110527.jpg
    20170912_110527.jpg
    322.7 KB · Views: 305
  • 20171021_192906.jpg
    20171021_192906.jpg
    169.5 KB · Views: 298
canyoncarver said:
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.
 

Attachments

  • 20171116_210441.jpg
    20171116_210441.jpg
    166.8 KB · Views: 303
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.
 

Attachments

  • 20171128_134857.jpg
    20171128_134857.jpg
    331.1 KB · Views: 292
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.
 

Attachments

  • 20171018_120819.jpg
    20171018_120819.jpg
    181.5 KB · Views: 309
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.
 

Attachments

  • 20171202_205815.jpg
    20171202_205815.jpg
    183 KB · Views: 291
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.
 

Attachments

  • 20171203_184109.jpg
    20171203_184109.jpg
    227.8 KB · Views: 291
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.
 
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.
 
Did more work on the bike, not so much free time around this time of year with work/family/friends/life but I'm hoping to plow through and hopefully get this project done by mid January.
Putting the bike back together has proven not so hard especially with the help of all the photos I took before i pulled it apart.
Have made some silly mistakes and have a few mental melt-downs. spent 2 hours Going over and over again on the electrics as I wasn't getting current.
I played around with the multimeter, put the battery on trickle charge, checked connectors, replaced old ones. finally after tracing it back to the starter solenoid I wiggled the main fuse line and bam! on comes the lights. Contact was in but wasn't tight enough. sigh...
Wiring for the lights, speedo, tacho and indicators on the front end have been done, some bullet connectors grouped and replaced with plug connectors.
Looking to replace the old combo handle bar switches with new ones but hit a slight hurdle. New switches are cheap online no brands with extra wires, took me a while to open them up and work out which were redundant and which I should splice together. hopefully later today I can get it sorted and matched up to the KZ's wiring harness.
On another note, because my forks are heavily scarred from rust, I've been trying to think of a (cheap) way to cover up and protect them.
I had some carbon fibre contact wrap which could have done the job but it looks out of place. I'll go get some flat black contact instead. I'd be happy to hear any suggestions on alternatives. I know I can get them re-chromed but it's not a priority right now.
Cheers
 

Attachments

  • 24956937_10155042371263639_826587743_o.jpg
    24956937_10155042371263639_826587743_o.jpg
    190.4 KB · Views: 653
  • 20171209_082042.jpg
    20171209_082042.jpg
    186.4 KB · Views: 286
The spare 2 go to the brake switch so they tie in to the loom. Older bikes tended to have those wires on their own.
 
I used electrical shrink tubing on my forks. I think from Amazon. Had to cut them off when I blew a seal, need to reorder. What a coincidence....mines a kz550.
 
Just a thought but what does your local Lowes/ACE/Home Depot have in the way of chrome finished plumbing for under sink drains? They may have a length of thin wall tube that would work. something like this but bigger... https://www.homedepot.com/p/BrassCraft-3-1-2-in-L-Chrome-Plated-Brass-Cover-Tube-for-1-2-in-Nom-Copper-Tube-8489-C/205214954?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-VF-PLA-D26P-Plumbing%7c&gclid=EAIaIQobChMIvPWrg-OD2AIV0kwNCh320AiJEAQYASABEgIVOvD_BwE&gclsrc=aw.ds&dclid=CLL28Ybjg9gCFU1qAQod4n4GQg

https://www.lowes.com/pd/KOHLER-1-1-4-in-Brass-P-trap/999956338

https://www.lowes.com/pd/Keeney-1-1-4-in-Brass-Slip-Joint-Extension-Tube/1070277

Start thinking outside the box.. :)
 
hahah I'm kicking myself for not thinking of that! I guess it shines a light on my lack of experience but lucky for me I'm in the right place 8)
These are great ideas, the shrink wrap is quick and easy, the chrome tube is brilliant, I just have to find a matching size of 36mm / 1.4 inch dia. I looked at dark chrome paint but i'm worried it will scratch easy so that idea is out.
I spent my free time today working on all the electrics, cut, crimp, solder, shrink wrap, replacing old connectors, splicing, testing switches etc.
I reworked the front brake light switch into the HB switch block(cheers Teazer). Works a treat now and helps tidy up the front end.
I sorted out the seat tray for the electrics, now most components are neatly housed, I bolted the new fuse box but decided to use velcro tape for the flasher and cdi. I figure that would be more than sufficient as they are not heavy items and can't fall out of the tray, I want to avoid drilling holes in the tray where possible.
So all was good, I'd finished cleaning up the wiring harness, weaved it back into the frame, connected everything up, I was all set to pat myself on the back for a job well done and head inside for dinner. I turned the bike on and ... some things didn't work.
Lights mostly. As panic mode started to set in I went over all the connections checking for lose wires but somewhere along the line I had maybe reversed some earth wires or something like that. As a result switches were jumbled up.
As you can imagine I was in a dark place for a while but I managed to recover some functionality but now I'm flying a little blind as the wiring diagram and previous switch blocks can only help so much.
I'm having to juggle between the switches and front end to get them to talk to each other. Fun fun.
 

Attachments

  • 20171212_220738.jpg
    20171212_220738.jpg
    200.2 KB · Views: 276
OK so all electrics are done! .... almost. I have an indicator problem. Rear indicators working fine. Front indicators not so much. So I have an electric riddle which I could use some help with.
Rear indicator voltage output is a healthy 12.54v
Front voltage Right side is 10.30v steady.
Front voltage left side is on a continuous variable voltage from 4.5v up to 8v and back down again...
It seems the indicators for the front that I want to use won't accept anything but 12v.
I can attach cheap indicators to the front which work though rather weakly.
I though maybe I could try removing and bridging some resistors on the indicators I want, though I don't know which resistors to remove.
How to fix please.
 

Attachments

  • 2017-12-13 20.11.40.jpg
    2017-12-13 20.11.40.jpg
    1.2 MB · Views: 315
Reposting - Ok so I found and resolved the issue!
After discussions with some local electric moto wizards (picture if you will, long beards waving around soldering irons) I was given a few options involving transistors or alternatively (the path I took) instead of running everything in series, I could run an earth from the indicator to the common earth in parallel with the existing circuit!
i.e pos + > Indicator > odometer > common earth. vs pos+ > indicator > common earth + odometer > common earth.
Once I wired up the second wires from both front indicators and connected them to the shared earth - boom - Merry Christmas.
So it would appear that these cheap odometers have high value ohm resistors in them to protect the 5mm LEDs and downgrade the voltage, problem with this is the output voltage - is not high enough for the indicators to fire up.
moral of the story - buy quality parts or waste time fixing cheap parts.
That completes the electric side of the bike for now. Later I want to introduce an LED voltage display into the seat tray and because I love LED's so much I plan to run some blue lights under the tank over the engine for that aesthetic look. Some folks might not like it but I think they're a fantastic invention.
 

Attachments

  • 20171214_214208.jpg
    20171214_214208.jpg
    82.5 KB · Views: 481
  • 20171215_215735s.jpg
    20171215_215735s.jpg
    254 KB · Views: 276
Great progress. Do not limit yourself to blue LEDs. There are all sorts of colors and some that change color. Some will argue that they are the sign of the lowest form of style, but I like them precisely because of that. They are in your face and fun - and they are only on when you want them on....
 
teazer said:
Great progress. Do not limit yourself to blue LEDs. There are all sorts of colors and some that change color. Some will argue that they are the sign of the lowest form of style, but I like them precisely because of that. They are in your face and fun - and they are only on when you want them on....
Totally with you on this, If I was king for a day I'd have LED's as a standard feature on all bikes. They look good (if tastefully done) and they help with safety.
I've got a plastic fantastic KLE650 with the full LED kit + remote. I'd sneak a photo of it on here but it's off topic.
Below however are the mods complete. LED lights and volt meter. I'm going with blue as it fits with the colour scheme. The tank and farings will be blue.
 

Attachments

  • 20171218_204312.jpg
    20171218_204312.jpg
    232.5 KB · Views: 277
  • 20171218_204321.jpg
    20171218_204321.jpg
    211.4 KB · Views: 271
So another challenge has presented itself. Today I filled the engine with oil, attached the carb and turned it over. Turn over it can but won't idle.
Pulled the carb out and gave it another good scrub. The bike still turns over and putts away but as soon as i take my finger off the starter, the engine dies.
Throttle does work to a limited degree, I can get it to rev higher, sort of.
In all my efforts I think I killed the battery, I have a back up to use but I'll need to come up with some strategies.
I'll be getting some fresh fuel, the stuff I have has been sitting around for a month, I think it's still ok but I want to eliminate possibilities.
Spark is good, timing and compression not checked.
Jets, idle and air valve to spec. might do more tweaking but that's tricky without a basic idle.
 
Back
Top Bottom