The 'build thread' of a Kawasaki Z250 C, a total beginner's point of view...


New Member
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So, after having posted in various sections, inevitably asking for help of sorts, I thought I would start a build thread, seeing as this has been the first day I've attempted to see what's happening with this bike. I'm not sure where this will go, to be honest I have 0 experience in any of this and have 0 skills which could be of much use as of yet, but I'm hoping to at least get this bike running again and from there, I'd love to make it as cafe as possible.

I'm hoping to use this as a log from a complete noob point of view, so that if there is anyone else out there who decides to buy a non running bike and then have no idea what to do with it, hopefully this can be a point of reference - for better or worse though I'm not sure.

Bike background:
Got this bike from Scott's Motorcycles in Sydney for $750. I sent them an email asking if they had any project bikes lying around and this one one of them. It had been sitting in the garage for 2 years, having run well before that before succumbing to a CDI issue. From my point of view, it looked like it was in a pretty good condition compared to the other bikes I was looking at in that price range, so I got it.

Photo of the bike as taken by the shop. I did see it in person, but honestly, it made no difference.

So once it was delivered, I had no idea where to start. The helpful people on the Australian DDT section definitely helped point me in the right direction. I was told to do the following:
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Check if the motor turns - did this by seeing if I could roll the bike (slightly) while shifting through the gears. If the bike seized up, then the motor was no good.
This was fine, but I had a slight complication with the bike not going into first, but that was fixed by rolling it around more.

See if I had a spark - take the spark plug out, put it back on the lead, ground it against the engine and hit the starter.
No spark. I wasn't expecting this to work seeing as I'd been warned about the CDI, but I looked around anyways and found what I believe is the culprit...

I had no idea what this was, so I DDT'd it. Hillsy came up with a great diagram which showed it was most probably the CDI. Great. I knew I had a CDI problem, didn't expect not to have one...

If all that went well, put some fresh petrol in it and start it up.
Well, I haven't got up to this yet.


Progress so far
So as I was saying, today was the first day of the build. I had a friend over who helped me roll the bike into my house, which was super helpful. So first on the list - see if it was really the CDI, so I went and stripped the bike.

How she now stands...

So, turned out it was the CDI. After stripping off the seat and those side panel things (no idea what they're called), I found the regulator, which was what other people thought it might have been, so damn...I was going to pay the 456 euros for a new one, and seeing as there didn't seem to be any after market ones for my bike at a decent price, I thought I'd try Jaycar...they had a CDI kit online for 98 bucks, which I thought was a bargin if that's how much I was expected to pay for a second hand one which looked rather mangled. So off to the shops it was, for that and some brake cleaner. Again, this was from advice from the Australian DDT, and would be used to clean up carb.

First up Jaycar. This is what a kit CDI looks like

Looked simple enough if it had decent instructions (read lego instructions, or IKEA instructions, or anything which is step by step)...too bad the instructions came from some article on CDI's. It would be helpful to people who actually know anything about electronics - I believe someone did warn me last night. But here, I've put up the link for anyone interested, or is looking into making their own

And seeing as it only turned out to be 20 bucks, I thought whatever, I'll give it a shot. Its a cheap stab in the dark. So I got that and a solder and I'm looking to try to put it together this weekend. I'm hoping my uncle can help me out, he's an engineer or sorts so I imagine he'd have more of a clue than me.

Up next was SuperCheapAuto, where I got some WD40 and brake cleaner.

So, at this point, I have to say it again - if anyone has a pdf copy or a print copy of the 1980 - 1983 Kawasaki Z250 Single Manual Service Manual, please let me know and, if its a printed copy, I will be more than happy to pay for it. I went about trying to dismantle the carb following the Z250 Twins manual (which I do have and if anyone needs I can send them the link) but realized pretty quickly that things were slightly different. So I improvised and here are the results.

Now I was too scared to dismantle this bit - the manual said I needed to use special tools, but people on this site do talk about cleaning the jets and needles and all that, so if anyone could tell me how to dismantle it, if it needs to be dismantled and cleaned, that would be great.

This seal thing caused me a lot of trouble - it attaches the 'butterfly valves' to the engine, but just wouldn't come off. You can also see the rubber has deteriorated pretty bad. Does anyone knows what this is called, and if I need to get a new one?

This is what I got it down to. I sprayed the other bits and pieces that were attached to it with brake cleaner, but I was wondering if this piece still needs to be dismantled further to be properly cleaned? It already looks pretty clean to me, but I do want to do a good job while I'm here. Another thing is that I'm not getting a very polished look other people are getting, just all the gunk is falling off it - is this what I can expect from brake cleaner? I saw another build where someone just soaked it in coke - is this a decent option? They're turned out pretty well, though I don't remember who it was, sorry.

So that's pretty much where I'm at right now. I'm planning to open up the engine just to make sure there's no surprises there, and hopefully if that's the case, clean it/soak it and work on the CDI while I'm waiting...

Really excited about all this. I realize its a bit of a ramble and there's a lot of unnecessary photos, but yeh.

A quick thanks to everyone who has already given me pointers and told me what to do, as by now you've probably realized I really don't know what I'm doing. My friend tried talking me out of it when he was over today, but just taking that carb apart got me excited. Ha.

Anyways, I'll try to keep this up and I suppose my future posts will be more to the point and less long. Every moment I'm here, I'm not working on the bike!





New Member
Would anyone know how to disconnect the tacho cable from the cylinder head cover? According to the z250/305 manual there should be a bolt and tacho pinion holder stop? I can't find it, but the cable definitely doesn't want to come out. Should I just yank it or will that damage it?

On another note, the $20 dollar socket set I got today already broke. Lesson learned, don't buy cheap tools...


Well-Known Member
Don't try to pull the diaphragm off the slide. That doesn't need anything other than a clean and to be handled carefully.

The carbs needs a few more parts removed. Remove the jets and clean them and blow through all the small holes and drillings. Don't be tempted to take out the shafts and butterfly valves. They are not supposed to be removed and there's no point.

Then carefully reassemble it and order a new intake manifold gasket if the bike came with one. There appears to be the remains of a gasket stuck to the face of that rubber intake manifold but many bikes don't use a gasket there. There's a raised ring around it that acts to seal it, but if your bike is designed to have a gasket there, make or get one.


yep, you have a good platform to start with there....

is that a drum brake on the front or a disc under cover?

maybe worth converting to twin disc if the cost isnt too prohibitive?

we had the gpz305 over here after the z250..maybe worth looking to see if the engine top end fits and if the front end is twin disc see if that fits also for any future plans as you improve it..just food for thought.. ;)

as for stylin..i will just leave these three here.........



New Member
Teazer - thanks, I was a bit unsure if I should take out the butterfly valves. Yeh there was a gasket on it, I had to rip most of it off cos it was badly deteriorated, but there doesn't seem to be one in this carb diagram I found last night:

The raised ring that you mention is also slightly cracked on the outside, though not inside, so I'm not sure if I need a new one yet.

Cyclone - that white and black CB is exactly the paint scheme I'm thinking, though in terms of mudguards and seats, I saw this on JobCrane92's build which looks to me like a z250 - I was originally thinking of cutting the subframe and not having a mud guard but supposedly its hard to get it registered in Australia if we do that, so I think that's definitely the way to go. I might try to get as close as that as possible - I'd be happy to get the bike running and looking nice for now - creativity can strike next time :)

Both my brakes are drum breaks btw, so yeh, the plan is to get some disc brakes on her, but probably not at this stage. Priority is to get her running first, then probably getting more familiar with riding, then cosmetics, then upgrading hardware if required.


New Member
So, the whole don't run before you learn to walk thing, and the 'remove all rubber before you soak your carbs in brake cleaner' thing...

Missed this obvious one.

Do I need to throw it out and order a new 'o' ring? I've been using spray on brake cleaner if that makes a difference - I realize you guys must all be using something else if you're posting photos up of it actually soaking in tubs...

Feeling pretty stupid about this one lol.


New Member
Just another question to add to my every increasing list. I've been reading about how people are using 'simple green' to clean their parts of rust and gunk in general, and some people have been soaking engine bits in it...

Just to clarify, seeing as I've been using this spray on brake cleaner stuff for the carbs, can I get some of that and just throw my carbs and other nuts and bolts in for a good clean? muffler too? I've read that it doesn't harm rubber, so I assume that's what people have meant when they said to just clean things like the diaphragm.

I'm looking at using Koala Kare, which I read on some bike (like cycle bikes) sites as being pretty decent. And its only $7 for 2.5L at supercheapauto. Has anyone used this before?

Anyways, I might give the CDI a go tomorrow night when I'm less tired and less bummed about this O ring business.


New Member
So just a quick update, begun work on the CDI. Had to get on youtube to see learn how to solder, and after the first two or so it got alright...I think. I hope I didn't do any damage on the first couple ones, I kept that soldering iron on the lead for quiet a while. Got some advice after posting up on 1800-cafe in regards to the connectors, so I'll ask around the mechanics to see if they have a plug I could buy. Otherwise I guess I'll have to order (and wait) online.

Hoping this CDI will work. It doesn't seem too hard to put together - I was wrong about the lack of instructions, its just that its not clearly written. The only thing you need to read is the last paragraph - and the outline of the parts are all drawn onto the electronic board or whatever its called. Will try to finish it tomorrow. Anyways, pictures below.

Wasn't very good at cutting these leads off...I'm just using the cutty bit on the pliers - hopefully having them jut out so much doesn't affect its functionality?


Well-Known Member
Carb cleaner in a can is great for spray cleaning and a small amount on rubber parts is not a problem. If one swells up, leave it in the garage for a few days and it will return to size.

Simple Green is a biodegradable, water based cleaner. I don't remember what else is available in OZ. That crack in the manifold comment could be an issue. I prefer to use nice new soft rubber intake/manifold and your dealer should be able to get on in for you. They always seem to be expensive to me, but that's the price you have to pay.

Check an on line parts list to see if it needs a gasket. Your dealer can check that for you too.

Connectors are available from Tandy/Radio Shack or on line. I got some at JAyCar but I don't remember if they had a 6 prong connector. Eastern Beaver in Japan has the best selection of waterproof and stock connectors - google them.

Back to the carb. Try to remove the brass jets to clean them and blast through any/all drillings with carb cleaner and then reassemble it. You don't need to soak the carb unless the small passages are clogged.

Get the bike clean and working and ride it. Then start seraching for ideas on how to stay within the law and achieve a cleaner look. Check out modern sports bikes. They use a vestigial rear fender to comply with ADRs and many riders take them off after they get the roadworthy and keep it for when they sell the bike.


New Member
Thanks for the reply - glad to hear the o ring still has a chance. I'll test it out. The crack is more on the base of the rubber which is wrapped around the 'carb holder' - the metal underneath is showing, but yeh, I guess I can get a new one - its only around $15 online which seems ok...

Yeh I finally realised what the connector does, so I think I will just get a new one if I can't find one of the same dimensions. Jaycar did have them, but I thought I needed exactly the same one, so didn't go for it. Here is another question relating to this but - I had a look at the wiring going into the connector, and based on the wiring diagram, there are 5 wires coming connected to it:

red = page level relay
green = pulse encoder
black = ignition coil
black/yellow = circuit brake light beam indicator lights flashing control idle control
red/yellow = engine stop switch button starter switch headlights and ignition coil

The strange thing is there are two red/yellow wires jammed into the same hole, so essentially, I have six connections. I assume that because the red/yellow has two functions, that is why there are two wires, but why are they jammed into the one hole, and can I remove this, or does it need to share that hole as I only have five external connections?

I assume that's why, but any confirmation would be great.

So here are the pictures of a nearly finished CDI - just need to solder on the wiring and hook it up. Seeing as the 'potting box' isn't sealed, and the electronic bits actually protrude from it, is it ok to keep this as is? I think it would be better if I sealed it with another piece of plastic or something...

You can see how I couldn't cut the leads properly. Does it matter that there is still so much left?

Anyways, plan for now is to get the battery out and charge it, find these connectors so I can finish the CDI and hook it up...and hopefully she'll purr :)


New Member
Oh by the way - would someone have an english version of that wiring manual? I'm not quiet sure which ones of the above wires will match the to descriptions of the CDI. As it stands I believe this is how it should go

Generator coil = pulse encoder
Kill switch = engine stop switch button starter switch headlights and ignition coil
Chassis = circuit brake light beam indicator lights flashing control idle control
Trigger coil = page level relay
Ignition coil = ignition coil

Would that be correct?


New Member
Took forever to get wires for the CDI out of the original connector. I gave up trying to preserve it and ripped it to shreds. Is there a better way of doing this? I found the new connector I bought doesn't have the same issues with the pins, so I presume its a rust thing, but I didn't want to spray WD40 on the wires, it doesn't sound like something I should be doing.

I forgot to buy a crimper too, so I might just try manually connecting these wires up and seeing if the home made CDI works. Just waiting for the battery to charge.



New Member
Hmmm so quick update. Finally got the new battery and the manual came, but a quick test tonight didn't prove anything in terms of how the kit CDI is. I stupidly thought the whole bike was suppose to be one closed circuit and any signs of working electronics would mean it works, but found out that not the case...

So without having had any success with the CDI I at least now know that my rear right indicator doesn't work, and I'm not getting any sparks when I hit the starter on the spark plug. I'm still not sure that I have the correct corresponding wires matching, so I might try testing all of them. Perhaps it doesn't work if I only have the ignition wires connection?



New Member
you wont be abel to test for spark until the CDI is in and functioning.

The CDI is what tells the spark plug when to spark.

Take some time to read through your manual, or other manuals for that matter.

You will soon understand how the systems work much better than you currently do.

Manuals are a great way to get to know mechanics in general, as they will spell out how part relate, how they attach, and how to troubleshoot systems.

There is a lot of info on DTT and other sites that simply explain how carburetors work, how charging systems work, how fuel systems work, and even how 4 stroke and 2 stroke motors work.

While this knowledge isn't strictly necessary to own or ride a motorcycle, it will help you a great deal on your journey to repair and then modify your nice little bike into something that speaks to you.

Take your time, be methodical, be patient, and do a lot of research. You can learn this.

Rocket Science it is not.

But you are a self professed "total beginner" (kudos to you for be honest with yourself, there's no shame at all in admitting/celebrating it) So there is a learning curve involved.

Some of this learning comes from this site and others on the web, some from your bike directly, some from other members/bikers/friends you can make contact with directly.

Be as much of a sponge as you can.

Many of us started at the same point of the learning curve as you are at right now.

For most of us here we are still climbing that curve, although it is not as steep as it used to be and the view is much nicer up here.

And for almost all of us our bikes are a source of a lot of joy/pride/exasperation that we cannot live without.

Enjoy your journey, embrace your mistakes, for you are learning and therefor living!


New Member
Sham, got the same bike in pieces at the moment. In melbourne, chasing the vacuum valve which l have noticed is the most expensive(over-priced)part for the carburretor. Do you have any links other than CMSNL? Would greatly appreciate that.

Had this z250 for 5 years not running for that long either. Just recently got into it and have it turning over with electric starter. After new battery and plug clean, carb clean, vacuum has perferations, so no actual fuel intake through 1 intake valve.
Slowly it will happen. Padi


New Member
So, decided to take some time off after the last ignition unit fail, which was fun in a way. At least I now understand a tiny bit more about electronics than I first started (the whole grounded and positive relationship was a start). Some good came from that little exercise - I found that the PO had a 15A fuse in place of a 20A fuse, and after replacing that, the left rear indicator worked fine =]

Was going to pursue the GM HEI modules as an alternate igniter, but was told that this would only work for mechanical advances, which I discovered (finally) my bike is not. So going back to the very start of this whole ignition journey, that Jaycar kit wouldn't have worked anyway if I understand the warning as being that it will not work for an electronic advance. So there. Fat waste of time that was lol.

So deciding to buy the OEM ignition module, which sells for around $400. But found a cheap, and more importantly, new module - half the price. The issue now is the seller will only ship within if anyone lives there, or knows someone there who would be willing to ship it back to me, PLEASE let me know (preferably within the next 4 days).

My earlier haste also means that I will need a new 6 prong connector after I destroyed the original. Also on the list is a new air box filter, as mine is missing the "sponge element" which the manual insists on being a very important part of the whole set up...also need to get a 8AG 20A fuse, as the one I'm currently using (3AG) doesn't fit in the fuse box and I'm thinking of getting a new set of hand controls - the labels on mine are all faded, and I'm missing the horn button. Any suggestions? I read in a previous thread that OEM was the way to go due to the complexity of the wiring that could be integrated in these things.

So I guess I have a shopping list =]

Padi - did you manage to find a cheap diaphragm for your carb? And did you get the link I sent you for the manual?


cheap, fast, and reliable PICK 2
yea when trying to get the the wires out of the connectors there is useally a PRONG of some sort holding into the connector. just use a micro flat head screw driver adn push down on the back of the wire.


New Member
Yeh I was just too excitable and rushed it. Now I'll have to wait...
But the good news is the German seller is willing to ship to Australia for no additional cost!? I think that's what he hoping it will be all good and can get this thing finally started!

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