Project DTZr.....a DT125R love story
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M MadGyver referenced this topic on
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When you’ve tried everything that is likely, all that’s left is the unlikely…
I think mr shadi had to disconnect the wires to the read switch while the revs were above 6-7000 for it to work…
I’d read his post through to be sure though…
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@Calum What can I check or test,any idea.
I have read topics here and on the old forum,the Yamaha club forum but no solution resolve my problem.
I'm on a dead end,followed the Yamaha service book,the Haynes, solutions from topics,whatever I could think,but now nothing. -
Sorry, I think I’ve confused you with another different thread. My bad 🫤 …Edit: Yeah, definitely misstuuke your Fred for another one. Sorry again. It was Har ptooie‘a thread I was thinking about…
It doesn’t help that every time I try and read back through this thread I get thrown back to post number 6! Is there some kind of lag with pics loading up? (iPhone user)
Do you have a power valve servo fitted? Have you tried running the bike with it disconnected? (If you do?) 5-6K seems like power valve territory…
Just hunching at anything that seems relatable… -
Managed to read the thread again! Need more info!
When it dies have you checked the plug? If so does the plug still spark? Is it wet?
I’m guessing that you have a solenoid box under the seat? (I have two) They are to do with the side stand switch/ignition cut out. Have you checked that these aren’t ‘firing off’ on their own @ 5K?
Have you got another key-ignition barrel you can swap out to try?
Have you checked the kill switch?I know that it might be reaching but you’re at the point where you have to try any&every-thing…
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@SpookDog The plug still sprarks but from the sides to the tip,not as it should,its' wet. I dry it and sparks still from the sides to the tip,it does it with new also. The spark is white and strong. I have changed spark plugs,spark cap,new original ignition coil.
Although a 4BL its a very early one (info from official Yamaha dealer in Greece with vin number) , it's cabling matches that of a 1989-90,original but refurbished by me to match the factory electrical.
Key switch is original used replaced the old damaged 5 years ago, it's mesured and is ok.Kill switch is refurbished by me to original and measured ok. The ignition system is measured step by step according the Yamaha service book and found ok.There is no solenoid under the seat,it doesn't exist in that model. Side stand switch is removed the right way, cabling reports always that side stand is up. With the side stand refitted does the same,side stand works ok.
I haven't try to disconnect the PV that you suggested before. It's 3 wire servo.
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Can you elaborate on the ‘sparks from side to tip’. Does it ever spark properly?…
Have you tried immediately replacing the plug after failure with a fresh one and checking the spark?Is it wet straight after it fails, or because you’ve been kicking it over trying to start it?
If it’s soaking wet straight after failure I’d look at your carbs main jet and needle tube…
Anyone ever had a main jet fall out?
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Have you checked the carb recently? Does it die at 5K rpm regardless of throttle position? I mean you can get it to rev over 5K just by cracking the throttle?
You’ve changed:
CDI
stator
Coil
Magnetic pickup
Plug
You’ve ruled out:
key ignition
Kill switchThere isn’t a lot left!
I’m wondering if the ‘feed’ wire to the coil (or to the CDI) has a break inside it? It can handle so much ‘pulse’ but breaks up its fidelity when it gets too much…
I can’t think of anything else @ the moment…
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@SpookDog Throttle position plays no role,I've tried increasing rpm gently or wide open but it's the same.Definitely not carb related.
It must be electrical,it changes run time with temperature,last time it run a couple of minutes at 38 celcius,but 4-5 minutes a day with 31 celcius,both at idle speed.
I'll get spark plugs from another brand to try,4 NGK bought together maybe bad batch.
@Calum You mean the orange cable,both CDI's the same problem?Waiting for a second 4DL cdi from ebay,bought at a low price counter offer.
I 've checked resistance at everything,even for the ground points between spots.I'll refresh the soldering points at both stator's,maybe a joint is failing but shows continuity.
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I know zip about electricity, so I am just guessing wildly, but what components are sensitive to timing? I mean, if the error is repeatably happening at 5000 rpm, then there should be something that depends on frequency, no?
Like not a spark plug as those happily ignite 20000 rpm with no mechanism that would make them fail at lower rates. Not switches because they either convey current or not, regardless of whether it would be a continuous voltage or a 1 µs pulse.
A rotor/stator could possibly fail if centrifugal forces make them lose shape or such? See anything possible loose there that may short-circuit at high rotational velocities? As for CDI, I have not the wildest idea how they work.
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@Hark_Ptooie If the spark plug gap isn't set correctly than the spark can just break down at too high a load. The spark plug annodes are saturated with voltage from the HT coil, if the gap is incorrect then this will cause issues.
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Only thing left is a break inside the wire. It might work ok until it hits a point where it just arcs. It doesn’t explain why it won’t start again though…
If you have a 3 coil stator and a side stand switch then you have little black box or boxes that controls the cutout. Under the seat near the air box… -
@Calum said in Project DTZr.....a DT125R love story:
@Hark_Ptooie If the spark plug gap isn't set correctly than the spark can just break down at too high a load. The spark plug annodes are saturated with voltage from the HT coil, if the gap is incorrect then this will cause issues.
Ah - makes sense.
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@Hark_Ptooie I'll refresh the soldering as soon as possible because this problem drives me crazy.Everything is almost ready except this and cannot go for technical inspection.
@Calum I'll order a new spark plug cap from Yamaha dealer,although the current is within specs and the original one.I prefer to have a backup if not used
@SpookDog no such box on this model,It matches the cable harness of 3RN1 to 3RN9 of Haynes manual or the 3NC that @HOTSHOT-III posted to another thread if memory serves correctly.Side stand switch connects with negative and then to CDI blue/yellow.
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@HOTSHOT-III said in Project DTZr.....a DT125R love story:
The actual coil on DTRs is very good quality so it's well worth fitting a new lead even to an older one; you can cut off the very top of the coil's outer case where the lead pushes in with a junior hacksaw, pull out the old lead and solder the new one to the coil output for a really good connection. Then re-waterproof using Shoe Goo and electrical tape. Looks messy but no-one can see it under the tank.
Do you have any photo to see what you did,it's interesting to know,I have an old one with short cable.
