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Discussion Starter #1
basically the title says it all. i bought this bike for my gf and it was hard starting when i bought it. its running one one cylinder. i had it running on both for a few minutes there but i have no idea why.

so far i have done

removed old fuel
added fuel additive
new premium fuel
cleaned the air filter
raised the needle jet with washers (jardine slip-on)
changed the plugs
changed the ignition coil

im out of ideas any help?
 

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verify spark. if no spark on one cyl, verify you have good power and ground for your ignition coils.

verify fuel. completely disassembly the carbs and clean them thoroughly. clean the jets and blow the passages out with compressed air etc.

if you're getting both spark and fuel you're most likely looking at a mechanical issue. do a compression and cylinder leakage test if both the other two conditions are met(spark and fuel)
 

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verify that the coil has battery voltage with the key on and kill switch on. then verify continuity of ground from the coil to the igniter box. if both those are good, check (AC)output of the pulser coil/crank position sensor with the bike turning over.

also check plug wires and cap(or does the new 250 use individual stick coils?)
 

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Discussion Starter #5
117 ohms at the crankshaft position sensor

continuity through the ignition coils through to the igniter

12 volts at coil

im stumped
 

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swap ignition coils not the plugs.

and voltage has nothing to do with it check the ohm reading on the coils. they have to be in spec to work. check the workshop manual to get the exact ohms you should be getting on the ignition coils. its a very low reading.

your plug is wet because it is not igniting because you have no spark.

Primary Winding Resistance 2.1 ∼ 2.5 Ω
Secondary Winding Resistance 10 ∼ 16 kΩ

make sure you are getting these specks on the posts of the coil. find a service manual and look at 16-35
 

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If you've swapped the coils there's not much point in doing the reistance checks - you know the coil is good. If you haven't swapped the coils, do that next.

There's only one sensor for both coils and much of the other circuitry is common. It's starting to look like a failed ignition unit. This is where a dealer can actually save you a lot of time and money, because he can simply try another unit to see if it works. THe problem is pointing toards your ignition unit.

I don't know if this model is CDI or inductive ignition. If it's CDI you won't have 12V on the coil. THe CDI pushes a (roughly) 400V spike down the coil and you need a 'scope to see it.. With the inductive system 12V is applied to the coil and the circuit is broken by the ignition unit. The collapse of the field in the primary produces a (roughly) 400V back emf spike. Both systems are commonly called CDI, but one of them isn't.


The reason I mention it is that with inductive systems it's common for a weak coil to damage the power tranny in the ignitor before it fails, and for the weak tranny to damage the new coil, setting up a cycle of failures.

Rob
 

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Discussion Starter #12
If you've swapped the coils there's not much point in doing the reistance checks - you know the coil is good. If you haven't swapped the coils, do that next.

There's only one sensor for both coils and much of the other circuitry is common. It's starting to look like a failed ignition unit. This is where a dealer can actually save you a lot of time and money, because he can simply try another unit to see if it works. THe problem is pointing toards your ignition unit.

I don't know if this model is CDI or inductive ignition. If it's CDI you won't have 12V on the coil. THe CDI pushes a (roughly) 400V spike down the coil and you need a 'scope to see it.. With the inductive system 12V is applied to the coil and the circuit is broken by the ignition unit. The collapse of the field in the primary produces a (roughly) 400V back emf spike. Both systems are commonly called CDI, but one of them isn't.


The reason I mention it is that with inductive systems it's common for a weak coil to damage the power tranny in the ignitor before it fails, and for the weak tranny to damage the new coil, setting up a cycle of failures.

Rob
yes i did swap the coils. both work. dead cylinder stayed.

I'm not sure i fully understand that. whatwould u suggest i do next? dealer?
 

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If you've swapped the coils there's not much point in doing the reistance checks - you know the coil is good. If you haven't swapped the coils, do that next.

There's only one sensor for both coils and much of the other circuitry is common. It's starting to look like a failed ignition unit. This is where a dealer can actually save you a lot of time and money, because he can simply try another unit to see if it works. THe problem is pointing toards your ignition unit.

I don't know if this model is CDI or inductive ignition. If it's CDI you won't have 12V on the coil. THe CDI pushes a (roughly) 400V spike down the coil and you need a 'scope to see it.. With the inductive system 12V is applied to the coil and the circuit is broken by the ignition unit. The collapse of the field in the primary produces a (roughly) 400V back emf spike. Both systems are commonly called CDI, but one of them isn't.


The reason I mention it is that with inductive systems it's common for a weak coil to damage the power tranny in the ignitor before it fails, and for the weak tranny to damage the new coil, setting up a cycle of failures.

Rob
the 250 has a TPI. we have established that he does have voltage present at the coils. collapsing field system. the only systems that are rising field are AC systems.

since we know he's got power, and he's got continuity to the TPI from the coil, and we know that the coil works when on the other cyclinder, we know that he has a control problem. it can still be either the TPI or the crank position sensor.

still need to verify output of the CKP while cranking. it should only be in the range of a couple volts AC. but you're gonna need a peak reading voltmeter to do it(or adapter).

though if one coil is firing correctly i highly doubt it's the CKP, but it's possible. most likely the igniter.


i know you said you checked the plugs, but have a go at swapping the plugs around too and see, as webbl19 said
 

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the only systems that are rising field are AC systems.
All true CDI (capacitor discharge) are rising field. A capacitor is charged up to about 400V then discharged through the coil primary.

Not sure what you mean by an ac system. CDI needs ac to give the 400V charge level through a transformer, with an oscillator providing the necessary ac component unless a DC/DC converter can do the job, but otherwise they're basically the same as the inductive system in terms of trigger and mapping. The igniter in inductive systems is basically an op-amp, and both systems run off a 12V DC external supply. There are some CDI units used on bikes that are self energising with an ac supply coil in the alternator, but these are the exception. These systems have to regulate and rectify some of the ac supply to support the mapping and the logic for trigger control.

Once upon a time I used to build CDI systems for cars using the stock contact breaker as the trigger. It switched a big power tranny to discharge the capacitor. Crude, but the difference it made to cold starting on some models of Ford was unbelievable. They were all discrete components, with a 2-transistor multivibrator feeding a hand wound transformer to get the 400V for the capacitor.

Anyway, the point I was making about 'wounded' components is that if its the ignitor I'd also replace the coil as a prophylactic. Op-amps are more tolerant than the FETs that used to be used, so I wouldn't replace the ecu along with a faulty coil, but I would replace the coil along with a faulty ecu.

Rob

Rob
 

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Discussion Starter #20
bike was bought from a private sale, from a guy who bought it at repo auction, bike has 1500 km. have not checked on warrenty because normally its just faster for me to fix than some of the "mechanics" at dealers. im pretty much at the stage of taking it to a shop stripped down (naked) and saying fix it.

i will call today about warrenty. what would void the warrenty as far as me fucking things up?
 
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