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2012 CBR250R - a build from the ground up (almost)

22K views 46 replies 10 participants last post by  KaiserR1 
#1 ·
Hey everyone,
I am going to be using this thread to document my build of a 2012 I just purchased. Feel free to follow along and offer up any advice you have, it's going to be interesting.


So, to start, I purchased this bike on CL and was told "it just needs an ignition coil, some fairings and a headlight". It was pretty clear to me from the beginning that he was under selling the severity of the bike's problems, but for the price ($800) I really couldn't lose. Here's how she came:




No muffler, no headlight, a gas tank that has more dents than straight portions, and wires that were all hacked up. Obviously I am in the habit of making good decisions.

When I got the battery charged (it was good! I couldn't believe it!) I turned the key, and she gave me a check engine light (what a surprise), and after looking at my new digital service manual (that I picked up on eBay for $2.50 as a pdf, emailed to me an hour after I purchased. I highly recommend this) and learning how to read the check engine light I found that I had 4 (!) Codes: 1, 8, 9, and 54. After looking through the wiring harness I found that the power supply to the intake system sensors was unplugged, and that managed to remove 3 of the 4 codes, which left me with the light for the bank angle sensor, because SURPRISE! It didn't have one.


I didn't get the best picture of the connector that killed the codes, but its,at the bottom of this pic.


So I went to work on the fuel/spark issue. I ordered a new coil, found some fairings (thanks MBzuki), a headlight, a bank angle sensor, some grips (driven d3 knockoffs, they're actually really nice for $5) and a new spark plug (guy didn't have the right model of plug in it.....some people.....).

After more inspection I found the 5P plug for the fuel pump had been cut at the wires, so I crimped those back together. Fuel pump doesn't make much noise....is that normal?

After I received the coil and plug, is put them in and hit the starter.......still won't start. The fuel injector is giving me some amount of fuel, not sure that it's enough but it's working. I removed the plug, stuck it to the head, hit the starter, and.....no spark. After looking through the manual, I decided a non-hacked up wiring harness would be a good next step, found one in good shape for $20, good enough for me.

So that's where I am right now. I expect the harness and bank angle sensor to arrive today, and ill see if the sensor fixes the starting problem (manual says it shouldn't matter, but who knows). If not, I'll route the new harness. If that doesn't fix it, it'll be time for a new ECM, unless anyone else has any ideas?

Questions for everyone:
What noises do your bikes make when the key is turned on and the switch is on run? I get a series of fast clicks from the IACV and that's it really...if I put my ear on the fuel pump I can hear a very faint noise...this isn't the case with my bigger bikes.

Also, if anyone has suggestions on what may be stopping my bike from sparking I would love to hear them. If it will run I will start putting her together.

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#5 ·
Do you have the proper clearances by chance? The service manual doesn't specify. All I can attest to is that it spun in accordance with a working IACV when not in the throttle body, and I re-installed it "by the book". It has been in and out a few times due to flow testing the fuel injector and inspecting the wiring harness. Thanks for the reply, you guys are being very helpful!

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#7 ·
I can verify that, as previously said, the motor moves freely when not installed in the throttle body, in accordance with the test described in the service manual.

Secondly, the post you linked has two replies: one says "test test test" and the other is an eBay ad for an old silverado.....perhaps you linked the wrong thread?

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#8 ·
#9 ·
Thanks Stichill, that second one was the right thread. I don't know what that first link was haha.

I'm thinking the IACV valve assembly is broken on this bike. It doesn't "spin gently to the motor assembly", if I spin it it just spins around on the end of the shaft, and I can see more of the shaft between the valve and the motor on mine than on yours. I'll post pictures when I get out to it this morning.

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#10 ·
So this morning I went about fitting the new wiring harness. It is for an ABS bike, so it has a few extra connections, but luckily the ABS is a standalone system from the rest of the electrical stuff (except for positive lead from the battery) so it isn't an issue.


New harness


Old vs new


Bike sans harness

The harness went on very easily, only took about two hours total. Turned it on, and the fuel pump still doesn't make noise. I still don't have spark. Curiously, the IACV stopped making funny noises, and the check engine light is off.

I have decided to buy a secondhand ECM, since both the fuel pump and ignition coil are led by it, and those are the things that won't work. All lights that are installed are working great, and the dash turns on, so I don't think there is a power issue. If anyone else has suggestions, again, please let me know. Currently I'm only $1100 deep, bike and all things listed on first post included, and a secondhand ECM is roughly $50, so I'm not worried yet.

Again, guidance or is much appreciated!

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#11 ·
Alright guys,

Got that new ecm today. Plugged her in. Still no spark, still no fuel. All fuses are good. This is starting to become frustrating. The service manual isn't really helping at this point, I'm running out of ideas but have come up with a few. Someone PLEASE answer these questions for me:

If you take the main ABS fuse out of your bike, will it start?

If you unplug your headlight subharness, will your bike start?

What is the black box that has a plug going into it on the front fairing stay, below the headlight? The plug on my harness doesn't exactly match the box.


If anyone could answer these questions from experience, or maybe run out to your bike and try this stuff real quick, it would really help me out. Thanks guys


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#12 ·
Alright guys, good news! I found the problem. You all had a lot of good advice. I tested the fuel pump with a jumper wire: works great. I tested continuity for all of the relevant wires, they all beeped. After looking through all of the issues, the only consistent possibility was the ignition switch.

Unknown to me, there is a third wire coming from the ignition switch that isn't represented on the service manual wiring diagram, the "security wire". The switch lit everything up when the key turned, so I didn't understand how the switch could be bad. So I said to hell with it, and pulled the top triple clamp off to inspect the switch, having totally run out of ideas at this point.

There are four safety torx screws that hold the wiring to the bottom of the lock. This switch only had three present, meaning it has been tampered with. I opened it up, and there it was:



See the little rectangle box with half a diode in it? There should be another half somewhere, but it has disappeared. Weird. Anyway, after searching the other forums, I found that this diode controls......wait for it.....the ignition and fuel output from the ECM. Boom.

So, now I need to know what size zener diode that is....would anyone know how to find out? Do I call honda and ask them for the size? I'm so close guys, help me get this last step finished so I can put this ******************** thing together!


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#13 ·
It lives! I replaced the burned up diode with a 5.1V 1W Zener diode followed by a 1k ohm 1W resistor. Plugged it all back up and turned the key and the pump started priming. Took a bit of finessing the throttle, but she fired up! Time to start putting this thing together

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#15 ·
Thanks Stichill, I was getting close to giving up, it started to seem impossible to fix!

The tricky stuff was really
1) finding the missing link, when the missing link doesn't exist in the service manual
2) figuring out how to mimic a 3.9V diode when all RadioShack had was a 5.1V diode and resistors.

Luckily all is well now, I'll keep this thread updated with the build as it comes along, I've got a lot of parts I've been collecting for when this day finally came haha

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#16 ·
If you don't have the bank-angle sensor (tip-over sensor) plugged in and properly oriented, you won't get spark. I think it probably kills the fuel pump, too. You need to source one of those (or bypass it). It connects to the fairing stay just behind and below the headlight.
 
#19 ·



So here is how she sits as of today. I'm waiting on a bolt kit to throw these fairings on, found a nice dark red gas tank for cheap in eBay (love that site), so soon she'll be looking good!

Two things I'm in need of at present:

- a not bent front wheel (may end up just having to bite the bullet and spend the $160)

-I'm having a very strange idling issue. When the bike starts it is initially happy, cold idles at 2K or so rpm, and then every time after about ten seconds it revs to 4k, stays there steadily for a bit, then drops to 3.5k and bounces, very regularly, between 3 and 3.5. It's really weird. This didn't seem to affect drivability when I rode it down the street, under load it drives fine even at lower rpm, but the second I pull the clutch in and coast it starts doing that weird bouncing. I would call it erratic idle, but it's very uniform in the rhythm of it, if that makes sense. If it stops raining long enough to pull the cover off of it today I'll take a video.

Stichill, you seem to know these bikes well, does this sound like the IACV to you? I'm going to take it out and clean it, if it doesn't work it'll be another thing to replace :/

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#20 ·
Stichill, you seem to know these bikes well, does this sound like the IACV to you? I'm going to take it out and clean it, if it doesn't work it'll be another thing to replace :/[/quote]

I think it has to do with no exhaust. I recommend the stock exhaust. I had a Delkevic briefly and it caused surging idle and hot stalling. Went back to stock and everything returned to smooth running.
 
#22 ·
Just did some very, uh, "scientific" experimenting with the effects of exhaust flow on idle, it's looking like you're right, Stichill. I took a brick and held it over the end of my exhaust pipe (started to do it with my hand, became obvious very quickly that wasn't going to work haha, derp) and it very quickly went from 4k down to around 1.5k, and I could modulate the rpms surprisingly easily with how much of the opening I covered. A guy on this forum has offered me his exhaust for a good price, I'll post the results after I receive it and throw it on

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#24 ·
Thanks Stichill, I tend to get a little obsessed with my projects haha, this one is no exception. It's looking like it is going to be a fairly cheap build after all, all new fairings, a new tank, and all of the other things I've purchased to fix it (not including what I'll hopefully get out of the parts I don't need on eBay) and the bike itself should end up running me about $1500, not too bad if you ask me! I'm glad I could bring her back from the edge of uselessness and turn her into something worth having.

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#25 ·
So, I got my new gas tank today, and started installing the fairings I purchased. After putting the headlight shroud together and attempting to install the middle cowl assembly I realized that the left side middle fairing bracket was bent pretty badly. Ordered a new pair on eBay, but I will continue with the rest of the fairing install and new tank! New exhaust pipe is on the way as well! Stay tuned!

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