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Discussion Starter #1
I just bought back an SV that I used to own about 3 or 4 years ago. The bike ran beautifully when I had it but now it doesnt start, that being the reason why the guy sold it back to me. The bike gets gas, turns over like a cha.p and has some spark. The PO purchased 2 new coils because of the weak spark but of course it was not the solution. What happens is that when I hit the starter the plug shows spark, not overly strong, and after 2 or 3 seconds the spark decreases and then disappears. Turn the key off, wait a few second , then it happens all over again.
1: there is a good battery supply as i cra k
2: lots of fuel pressure
3: good air flow
4: all coil leads are new or clean
5: all fuses check out

I would really like to get this bike figured out and running as it is in aweso.e condition. I was a member here under a different name when i had this bike but i could not ressurect my old account when i tried. I purchased the SV damaged and had a ton of fun rebuilding it (mostly cosmetic) into a custom looking ride to fit my wants. Al9ng the way I documented the build and im pretty sure i posted it up here at the time.
Any and all help or leads on the issue Ive described will be much appreciated. Thx
 

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Check the primary resistance on the coils....should be in the 4-6 ohm range, any more or less will not work properly. If they check out OK...I'd want to see cranking voltage at each coil before going any farther.
 

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Discussion Starter #3
thanks for he reply. i was never into the electric side of things on bikes as far as diagnosing issues go. but i guess now its time to learn. i guess i will need a voltmeter 1st? and how do i then check both items you mentioned? thank you.for the help.
 

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Yes....a multi-meter is pretty much a necessity when trying to track down an electrical problem. Often times you can use a simple test light...but when resistance or volt measurements are called for....the light won't work as well. A good meter won't cost a lot (no need for a Fluke) and a very decent one can be had for $40 and a serviceable version for half of that.

The coil resistance test measures the primary coil which is wound within the secondary. The '+' terminal should be 'hot' (battery voltage) when key is on and the '-' is then grounded by the ECU when it saturates the coil prior to firing the spark. When the '-' ground is removed the magnetic field that the primary coil had created collapses which then induces a very high voltage in the secondary windings (because they're often wound 100:1) and this is what creates the spark across the plug.

When the ECU grounds the negative terminal and current flows through the coil, the amount depends on the voltage and resistance and too little resistance will flow too much current which can damage the ECU. There ARE coils made with very low resistance which are intended for 'CDI' type systems...and for some reason many people seem to believe the SV's use CDI....but they don't and haven't so a normal coil type is used. If you substitute a CDI coil the SV will NOT be happy.:)

Hooking the multi-meter to the '+' terminal on the coil should show battery voltage and how much you have while cranking determines how much voltage it can create to start the engine. It should measure within a Volt of what you see directly at the battery terminals if the wiring is OK.

One other thing to make sure of: the coil wire polarity does matter. The engine can run with the '+' and '-' wires on the wrong posts but the spark will be jumping the wrong way and can be less effective as it's not designed to work this way. Some engines DO run sparks both directions when they share coils on two cylinders...but that's another thing unrelated to us here.

Do you have a service manual? There are some available for download online (free!) and the factory version is VERY comprehensive about how each system works and has pinpoint tests for each component which makes diagnosis a lot easier. Don't worry....learning the bike will be a lot of fun, and it'll pay dividends for the rest of your life.:)
 

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Are they factory coils or aftermarket? Even if they are new aftermarket that may be your issue. I spent weeks on the ‘03 I have thinking the coils were good as they looked new but once tested with a meter I verified that was the issue. Another set of used factory coils and it started right up.


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Discussion Starter #6
i am going to start by taking advice as mentioned and getting myself a meter and learning how to use it. also to answer the last question the replacement coils are new and im assuming aftermarket. according to the po the symptoms continued after the new coils were instàlled. so basically what happens is that the spark on the plug, while the plug is out and attached to plug wire with starter button pressed, starts out being what i would consider less than strong and just fades away in a second or 2 to non existent. wait a few seconds and it happens again. the plugs are new as well i just popped a random plug into the cap with the same outcome. im going to start testing the coils outputs as suggested but im wondering if anybody has ever heard of anything like this before. also the po mentioned to me that when the bike 1st started giving problms it would start, drive normally for a few minutes, and then shut off. just throwing that in there in case it helps or means anything to anybody. and in case anybody reading this is interested my old username here was woodsv. if you search it up you eill find a small build thread on this bike back when i first got it in 2008.
 

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Be sure you carefully inspect the Green Connector (comes from the ignition switch and powers the bike) as they've fried many times before and when it's happening the bikes can die a slow death as their volts get slowly strangled. The coil voltage test while cranking would likely show this as they can only multiply what they're being fed...and if the feed voltage is dropping so will the spark intensity.
 

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Discussion Starter #8
Be sure you carefully inspect the Green Connector (comes from the ignition switch and powers the bike) as they've fried many times before and when it's happening the bikes can die a slow death as their volts get slowly strangled. The coil voltage test while cranking would likely show this as they can only multiply what they're being fed...and if the feed voltage is dropping so will the spark intensity.
thanRob. just got my hands on a meter today and am planning to test the coils tonight afterwork. so when i test the coils where should i be placcing the leads from the meter? i quickly tried one of the old coils that the PO removed by placing each lead on the body of the coil: bssically each end where the bolts pass through to connect the coil to the bike frame. that read 4.6ohms. is that how i should. test the coils.on the bike as well?
 

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Discussion Starter #9
thanRob. just got my hands on a meter today and am planning to test the coils tonight afterwork. so when i test the coils where should i be placcing the leads from the meter? i quickly tried one of the old coils that the PO removed by placing each lead on the body of the coil: bssically each end where the bolts pass through to connect the coil to the bike frame. that read 4.6ohms. is that how i should. test the coils.on the bike as well?
i meant to say thanks rob , not thanRob lol
 

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The primary resistance is measured from the '+' terminal to the '-' one. Think about where the current must flow to charge the coil....that's what you need to measure. Then on the '+' with the red lead and the battery negative terminal for the cranking voltage test.

One thing to remember when testing things on the SV, being that it uses an aluminum frame they don't use it for a ground path....all grounds are wired back to the battery and if you ever add something electrical you should also wire a dedicated ground back to the battery. Reason is galvanic corrosion which can and will occur when current is flowing through aluminum which makes the frame a poor ground.
 

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Discussion Starter #11
not having much luck with things. when i put the meer leads on the coil + and - i just get a series of numbers on the meter until they eventually just return to zero..not sure if its this meter, me, or what..being electrically challenged here am truly at a loss a how to read this
 

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Discussion Starter #12
so after trying to test the coils and the cranking output as recoilrob advised i am not sure what to think. the meter i have, set to ohms, isnt rrally giving.me a set number for either test but rather a constant fluctuation of readings. im guessing that either the meter itself is not of great qualith or more likely i am not knowledgable enough to properly interpret them. i have to wonder tho if anybody recognizes the symptoms of the bike. as i push the starter with the spark plug out and in the cap the plug displays spark for any given amount of time such as 2 or 3 seconds. then it stops sparking
if i keep pushing the starter it might spark again or maybe not
there really is no pattern to it. i really would like to get to the bottom of it as the bike has a bit of meaning to me. when i rebuilt the bike back in 2008 my father was alive and very much a part of my life in every aspect including the building of this bike
i couldnt wait to tell him what i had done to it as every day went by and more progress was made. and of course he was always admiring the outcome and praising the build. now my 12 year old son is watching me at the bike as he does with all of myprojects around the garage and he has already told me that because the bike means so much to me that he wants tobe the owner of it when he gets his own bike license.so now i HAVE to get this thing running so i can make it safe and good looking for him lol. so ANY AND ALL advice is very much appreciated. and btw i DID look at the green plug from the ignition and it was burnt. however it already has been repaired and i did check the repair to make sure it was done properly.
 

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It sounds to me like the instrument is operating correctly and the insulation inside the coils has broken down.

Check the instrument first though: make sure it is set to an ohms range (cheap meters often have several, none will be very low, so pick a kilo ohms one. Hold the probes apart and it should give infinite resistance, touch them together and it should be zero (or close to - there might be a null button to press and set that to zero). Now measure some things you know the resistance of, this will check the meter and build your confidence it it). If you have some use some resistors (from somewhere like Maplin in the UK or Radio Shack in the US). If you don’t have any use some things you have around - a piece of wire (less than an ohm), a light bulb (about an ohm), a LED a kilo ohms. You will be able to find some things to test around the bike or on your car - leave the power off.

These should all give steady impedance, if they don’t the instrument is no good. If it is okay check the coils again, if the primary impedance varies the insulation is no good and you need some new ones.

Good fortune,

Alan


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Discussion Starter #14
after a break from trying to figure out whats otg with this bike im back at it. i purchased an automatic meter
i seem to be getting the numbers that were suggested on here so i suspect the coils are good. in fact i kind of thought they were as they are new replacements. so any suggestions as to what next? im really looking forward to getting this figured out so i can move on to a bit of customization work over the upcoming winter months.
 

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... the replacement coils are new and im assuming aftermarket.
As Buckwheat said, and if you haven't already, replace the aftermarket coils with stock. That should be step 1.

The stock SV coils are excellent and designed to match the ECM ignition coil driver output impedance and dwell.

Aftermarket coils offer no benefit and good chance are not electrically compatible with the SV ECM.
 

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Discussion Starter #16
so at this point ive determined that the coils are good. and they are in fact oem. so both front and rear plugs are providing intermitten and fading spark and mostly nonexistent. curious as to what is suggested to look at next. any and all comments are much appreciated btw. i thank you
 

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- Try measure voltage at the coils, should see 12v on Orange/White (front coil) and Black/Orange (rear coil).

- Do both plugs behave identically, equal fade, equally intermittent?

- Have you seen this with your own eyes or is this info from the previous owner?

- As a sanity check, try visually check spark in a dark garage or at night. This will give a better indication of what is going on. It can sometimes be hard to get a good visual on spark in bright light.

- Does the engine run at all? If fading spark is the real/only problem here then if spark is initially good for a few seconds the engine should at least start then die.

- If the nighttime spark check shows consistent spark, this might be a fuel problem.
 

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Discussion Starter #18
voltage measures 11.84 and 85 at the front and rear coil.

both plugs are equally erratic whereas there is absolutely no pattern that i can see to the spark or loss of spark. and one or both willl have spark for a few seconds at the same or different times.

I have seen this myself tho i was told by the po as well. however i did experience theae symptoms and do the checks myself

i did check in the dark as suggested anf as luck would have it there was absolutely no hint of a spark this time.

the bike used to run for the po but it wont even make an attempt now.

i am inclined to think this may be a problem back up the line from the coils. i figure thi if i keep updating and following advice from you guys i WILL get it eventually
 

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voltage measures 11.84 and 85 at the front and rear coil.
High 11v range is low but not low enough to cause no spark. Should see at least 12.0v min with the key on, lights on.

While working on the bike it will help to remove the headlight fuses and keep the battery on charge until the problem is solved. That will make sure the battery stays up and prevent introducing a low voltage problem on top of the existing condition.

... there was absolutely no hint of a spark this time.
Given that spark is now 100% dead (that is good, makes for easier debug) wiggling the harness and connectors at the ignition coils, ECM connector and CKP connector while simultaneously checking for spark may give a clue. If wiggling wires gets spark to return, even intermittently, then for sure the problem is a poor connection somewhere.

Make sure the spade connectors at the ignition coils are tight. If loose, the connectors can be removed, squeezed tight with pliers, then pushed back on.

Also inspect the connector at the ECM. Remove, look for debris or bent pins. Re-plug the ECM and be sure it is full seated. Since this bike is new (again) to you, need to check everything, no telling what the previous owner did. :evil6:

...i am inclined to think this may be a problem back up the line from the coils.
A good clue here is if spark fails at both plugs identically that points to a problem common to both coils, "back up the line" as you say. That would be the ECM, perhaps the CrankPositionSensor (CKP), and possibly, though not likely, the harness.

If spark fails independently (one plug fires while the other does not) then likely the problem is local to one coil/wires or the other, the CKP would be eliminated.

... i WILL get it eventually
No doubt, you will fix this. :) It is only a motorcycle and the SV ignition system is a fairly simple beast.
 
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