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-   -   Old ZX12r wont start, advice for debugging (https://www.kawasakiworld.com/zx-12r/66806-old-zx12r-wont-start-advice-debugging.html)

stube40 03-23-2019 04:59 PM

Old ZX12r wont start, advice for debugging
My 2000 12r has ALOT of miles on it, but really hasn't missed a beat ever - amazingly robust bike! Until now though.....

I'm suspecting the starter motor has gone. Here is what I can tell you:

First sign of trouble was just after a 30min drive. I turned bike off then decided to start it up again straight away but I noticed it really struggled to start. Like starter motor was struggling to turn engine. Bike was fine for a few more days of regular daily commute after that, but then failed to start one morning with following symptoms. Bike turns on as normal. Everything seems to happen as usual - the rev counter and speed needles do their test. I can hear the whine of (I presume) the fuel pump etc. Appears normal. When I press start button the engine does not turn over, but I do hear the same fuel-pump sound (or whatever that high-pitched whine is) as long as I have my finger on start button. Battery is not old, although not brand new either. I have taken it out, charged it, measured voltage with multi-meter (12.5V) and all seems good. Although I have not done a full battery test so can't guarantee it is that

Any tips?

Barbarian-CBX 03-23-2019 05:22 PM

Still might be the battery. I'd buy a battery tester first. Put on 4 way flashers and push starter button. See if they dim. Push horn button and push starter button. Did horn die?

12R's are notorious for doing crazy things when a battery is going bad.

Sent from my SM-G955U using Tapatalk

stube40 03-24-2019 12:59 AM

Thanks - great advice. Tried both tips. THe 4 way flashers didn't dim and the horn note dropped a TINY bit when I hit the start button, but otherwise continued as normal. Based on this, battery seems good I think?

So quite possibly looking like starter motor replacement?

ninjayorkie 03-24-2019 02:09 AM

When It happens again, put the bike in gear and rock the bike, pull the clutch lever in and then try.

Like you say it could be that the starter motor just needs removing, stripping apart and cleaning, they're not hard to do.

stube40 03-25-2019 04:49 PM

I tried rocking it back and forth in gear - did it 3 times and nothing changed. However, on the 4th time I was sure that it sounded slightly different when I tried to start, almost like the starter motor was trying to get going (it was really subtle and quiet). 5th time it was just the same as the first 3 times - nothing other than the usual high pitch whine.

So looking alot like the starter motor? I'm quite happy to give it a go to try and remove it and strip it apart. Done lots of things on the 12r before, but never once looked at the starter motor - I don't even know where it is on the engine. Do I need any specialist tools?

KZScott 03-25-2019 05:02 PM

is the neutral light on?
is your clutch switch working?
kickstand switch?

ninjayorkie 03-26-2019 01:51 AM

These pictures and youtube video are for a zx-9r but the differences are only noticeable if you try fitting a zx-9r one into you 12 as the drive shaft are different sizes so won't work.

I'll just add I've never removed one from a zx-12r so I don't know how much room there is at the back of the engine for ease of removal.

Anyway here are some pictures. Take your time when rebuilding it and don't force anything. It's the brushes your wanting to check and to clean the armature where the brushes rub. Plus clean out all the crap that will be all over the insides.

http://s27.postimg.cc/81fis00tr/zx9_...ment_marks.jpg http://s28.postimg.cc/9yiq3bmjt/zx9_starter_motor.jpg

http://s7.postimg.cc/pbome09av/zx9_starter_parts.jpg http://s27.postimg.cc/oy96y5xrj/zx9_...rebuilding.jpg

This is not me by the way.

Duck00 03-26-2019 02:51 AM

I've removed mine a couple of times recently to clean up the bushings etc, made a bit of difference.

It can be taken out, just a bit fiddly, one of the coolant pipes (to back of cylinder block I think) is sitting in an awkward spot, but can be done. The manual makes it look like a simple procedure, just take your time.

stube40 03-29-2019 04:30 PM


Originally Posted by KZScott (Post 705468)
is the neutral light on?
is your clutch switch working?
kickstand switch?

Thanks KZScott,

Neutral light is on
When I put it in gear, neutral goes off. When I try to start it in gear the FL light flashes, but stops flashing if I pull in clutch. So I guess clutch switch seems OK?

KZScott 03-29-2019 04:39 PM

sounds like those are ok, i would check the solenoid or the starter next

stube40 07-20-2019 07:30 PM

So update on this thread - yes, I let the bike sit for months and did nothing.........So the short story is that it is the starter motor and now I need to find somewhere to buy a new one or a reconditioned second hand one, but in the meantime I wanted to share my experience to help others:

First of all I tested the solenoid as suggested. It is really easy to test, although having the service manual is helpful to work out the connections. You need to remove the entire battery/relay box, but other than that it's easy. It is SUPER HELPFUL if you have some electrical test-leads with spring/croc clips on them. COnnect it all up and you will hear a loud and positive click as the relay turns on and the multimeter will show short circuit to show that the relay is working find.

So next step was the starter motor. I wouldn't say it's easy to remove, but it's not difficult either. Again, service manual is helpful. It's really only one cable that needs disconnected and two bolts and the thing can come out, but it does need a bit of wrestling to get it out past all the cooling pipes.

Once the starter motor is out I tested it by using the same battery/solenoid setup that I had used to test the solenoid, except this time you are putting the starter motor in series with the high voltage output from the starter solenoid. You can use car jump leads for this to help, they are perfect and the legnth allows you to put the starter motor on the floor and put your foot on it (remember that if it works the starter motor is going to violently try to move). When I tested the motor didn't turn at all so I knew this is where the problem lay.

While I was testing it and getting nothing from the starter, I tried twisting the output shaft and low and behold it starter turning - bingo, so probably the brushes right?

Next step - pull the motor apart. Now this bit is super easy. Just a couple of bolts and it almost falls apart. Interesting enough, I got traces of smoke coming out as I opened up. My guess - excess carbon from the brushes burning. As I opened it up I was presented with a chamber that was full of carbon powder - 19 years work of brush degredation. There was still some of both brushes remaining but not much (maybe 2mm ish max). I cleaned the whole thing up and reassembled then re-tested and it worked perfectly. Span up on every test. But I was surprised it wasn't particularly violent/strong when it started up (this was a clue I think).

Anyway, I reassembed the starter motor into the bike. Getting the starter motor to slot back into the engine is a little tricky, I guess because the teeth on the shaft have to match the position of the cog in the engine or it wont go in. Took me about 2 or 3 attempts of adjusting shaft position on the motor then re-offering it up to the engine before it slotted in, plus it needed a rubber mallet to push it in with a little tap rather than the strength of my hand alone.

Sadly when I tried to start the bike nothing had changed - it still wouldn't start. I could hear the starter solenoid switching, but nothing from the starter motor. My guess - either the brushes or the armature are so toasted that there is no cranking strength in them so it is trying to turn but getting nowhere. Although, I'm surprised I couldn't at least hear/feel something from it, but there was nothing at all.

In summary, 90% sure the starter motor is screwed and now looking to source a replacement. If anyone has any suggestions then I'm all ears!

ninjayorkie 07-21-2019 01:25 AM

3 Attachment(s)
Thanks for all the feedback, just check the earth cable from battery to engine is good and not damaged and its contacts are clean.

You could try fitting new Brushes. Search eBay for something like "Carbon Brushes Pair For Starter Motor Kawasaki ZX12R A/B 00-06" That will bring up at least one result.

You may be able to get a zx-9r C E or F starter motor cheap and the brush section may swap over, I may even check for you on the two I have here if I find time today. :smile2:

OK, now done. :thumbup: Don't mix up the armatures when rebuilding.

Tazio 07-24-2019 05:41 PM

The commutator on the armature could have one dead segment and if it lands on that spot it won't pass current. You should also check the voltage at the starter between the starter housing and the power stud to make sure it's not a ground problem.

stube40 07-24-2019 08:35 PM

Thanks Ninjayorkie and Tazio!!!

SteveW 07-27-2019 05:57 AM

Nice post Yorkie!

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