Quick help please, no tacho, lost a cyl or two

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banner001
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Re: Quick help please, no tacho, lost a cyl or two

Post by banner001 » Sat May 04, 2019 11:07 am

Sorry for the off message, I had the reply box open on my phone this morning and did t think you would reply to yourself...I think there is a CDi resistance check in the manual that you can download from the main page...pretty sure I've seen something in there.

Failing that, the cdi must send your signal to ground, you could see what wire grounds the cdi, and then test the resistance from the green wires pin to that ground, and then the same for the black wire, am wondering if the black wire has an open short on it...might explain why it gets hot too...
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

Catalin24
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My Bike: ZXR 400 L5

Re: Quick help please, no tacho, lost a cyl or two

Post by Catalin24 » Sat May 04, 2019 12:46 pm

Found a few faults, the CDI is bad. Found the internal resistance check table, fails it quite badly on most of the checks. Opened the CDI unit, found one bad transistor(there are 2, I presume for coil 1 and coil 2) and 2 resistances that we’re overheated in line with the transistors.
Removed the bad transistor voltage dropped to 0.5 with fuel pump relay connected. With the fuel pump relay disconnected 0.01v. I believe all is good until here.
BUT when I connect the tachometer I get 12v again on the coil 1&4 wires(bk and red) so I guess my tachometer has a short somewhere.
So I believe I need : new cdi( if I can’t fix this one), starter relay, coil 1&4 , new tachometer or dashboard (if I can’t fix it) ... sounds bad, maybe I’m not thinking straight any thoughts?

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Re: Quick help please, no tacho, lost a cyl or two

Post by banner001 » Sat May 04, 2019 5:29 pm

I would keep the coil for the meantime, I'm not 100% sure about the tacho but I think it might be working fine as it is, i.e. it might measure the frequency of the groundings through the cdi and use that to show the rpm...

I say buy a new cdi, keep.the current coil, disconnect the tacho and fire up the bike, if it fires up on all 4, turn it off, reconnect the tacho and see if it's still ok.

If you feel you want to replace the coil you can, I just dont think that's the source of any issues you are having
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

Catalin24
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Joined: Sat Oct 07, 2017 7:36 pm
My Bike: ZXR 400 L5

Re: Quick help please, no tacho, lost a cyl or two

Post by Catalin24 » Sat May 04, 2019 6:09 pm

Oh banner, I’m truly aware that the coil has nothing to do with the no spark problem. The fault comes from the CDI 100%. The coil I believe it will work fine at the low rpm and might break up at high, either way I’ve found a cheap replacement as well as the starter relay. Now I’m waiting for Monday to come to buy that transistor and resistor and see if I can revive the CDI. Checked the resistors are 680ohm 1w they seem fine both though they look a bit worse for wear. Called on a source to find a CDI replacement as well, need to wait for now.

Yeah that was my plan, fix or replace the CDI and start the bike without the tachometer and see what happens. Pretty sure it should start on all four cylinders. And then connect the tachometer an see if it still works.
I don’t really know what to say about the tachometer it seem weird to me that it would give constant 12v on coil 1&4 and nothing on 2&3. Tried to bench test the tachometer, no success. Although I have pretty much no idea how to feed a signal in it, I tried the crude method of feeding it 12v on the bk wire and also powering it on bk/y and br, nothing at all. Checked of shorts between all 3 wires. Nothing. All seem to have somewhat of a resistance so you might be right banner. But still, it seems odd with that 12v feed at the coil 1&4 wires when I connect the tachometer. Tested for continuity between bk and chassis ground, I didn’t found anything if I remember correctly.

Oh yeah, those 2 transistors are indeed for coil 1&4 and coil 2&3. They are NPN with code D2141 if it helps someone. If I short between the Emiter and the collector (as the bad transistor from coil 1&4 was) it indeed sends continuously 12v to the coil respectively. I.e I shorted the good transistor (coil 2&3) between the emitter and collector and i got a constant 12v at the coil 2&3 as well. So I could get away cheaply with the CDI. Looked to me that it was opened before but no signs of soldering on the pcb. Or it was really professionally repaired. But I doubt it.

Catalin24
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Re: Quick help please, no tacho, lost a cyl or two

Post by Catalin24 » Mon May 06, 2019 12:40 pm

New update, replaced that faulty transistor in the CDI didn’t found the 680ohm resistors so I reused the old ones. I no longer have 12v on the black and red wires. Unfortunately I didn’t found the exact replacement transistor but I used a similar one I guess. Anyway, Long story short it doesnt work. Still No spark on 1&4 .
Trying to find a replacement Blue M CDI now... i hope i can get one locally. Still no idea if the tachometer works

Catalin24
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Joined: Sat Oct 07, 2017 7:36 pm
My Bike: ZXR 400 L5

Re: Quick help please, no tacho, lost a cyl or two

Post by Catalin24 » Tue May 07, 2019 6:58 pm

Didn't found any Blue M CDI units, any luck on forum? Does somebody have a spare? Ewetea might help me out with an L unit till I find a M one. (many thanks :excited ) As for testing the tachometer I've found in the manual how, gonna try it tomorrow. If it helps anybody here is how you test your tacho:
You need to get to the coil 1+4 , switch ignition key on, and apply battery positive to BK wire from coil 1+4. The tacho needle should flick. No flicky-flick , dead tacho.

Catalin24
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Joined: Sat Oct 07, 2017 7:36 pm
My Bike: ZXR 400 L5

Re: Quick help please, no tacho, lost a cyl or two

Post by Catalin24 » Sat Jun 29, 2019 7:34 pm

Update: I have managed to fix the CDI with Ewetea’s help and he was kind enough that provided me with an secondary Blue L CDI as a spare. For now the bike works well except when she get hot the engine is sometimes hard to crank one time the battery was low 12,30v. Now it shows that it’s fully charged at 12.81v. I’m a bit confused. I have an Varta AGM powersports 8Ah 135 cranking amps. The headlights Looked weak, so I suspect the battery. I had the same battery and it died in less than 6 months. This one I had it tested with specific tester and the gentleman said all is good. (The battery and the bikes charging system) but that was last year I guess I’m gonna go again to check it again.
Found on forum that the starter wires could get an upgrade and would improve the turning speed when hot. For now I’m bump starting it when she’s iffy.
Ps: what’s with the clean-up? I’m not very active but I would still like my account, this forum helped me a lot with my zxr.

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Re: Quick help please, no tacho, lost a cyl or two

Post by banner001 » Sun Jun 30, 2019 4:12 pm

Hi there, I make the battery wires for pretty much cost price and can make you a set if needed. If nothing else it rules them out as being a possible source of failure.

I'm currently using a very nice battery that seems to have cured all my starter issues when the bike is hot. The standard battery is a ytx-9bs with 130ccA, motobat do one with 160ccA, but the one I'm using is from yuasa it's a yt12a-bs with 175ccA and it's holding out well so far, think it was £60.

Has to be that exact model though, it's exactly the same size as the ytx-9bs so fits the battery box perfectly...
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

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