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Ignition Coils - Buyer Beware - my Nightmare - need help

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For something I need input on see my last sentence.

OK I've been struggling off and on for a long time with my particular nightmare - a 1995 yamaha XT350 - no more yamahas for me but that's another topic.

I'm struggling with weak or no spark, and also a lean carb mixture, which I can deal with later.

Here's the deal I think people should know, I have been through at least 3 new ignition coils, but when I bought them new I assumed they were OK and never tested the Ohms on the secondary coil. 

Today I tested the brand new one on the bike and found the sec. coil was around 15 KOhms.  spec from Clymer Manual is around 5-7.  So I tested some coils I had lying around and the only one that was close to spec (around 4.2 kOhms) was one I had sliced off the plug connector.  So just to mess around before thinking of buying a new coil I soldered and heat shrinked a connector from a bad testing coil to it, put on bike and still no spark.  Tested the secondary coil and it was around 15 kohms like the others.  I figured my CDI is somehow frying my coils?  Just to check I then sliced the plug connector back off at the solder joint and remeasured twice - Back to 4.27 Kohms.

These things are cheesy as heck - the plug connector connects via a crappy wood screw most likely steel, screwed into the wire.  Yes, even the yamaha (yakuzi?) one.

 

Anyways, how to find a plug connector I can solder on that is halfway decent ?  These cheesy things have the crappy smaller connector that requires removal of the little screw down hat on the plug. 

Thanks!

 

Edited by rotagen

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I think you are asking about an after market spark plug wire and cap?

NGK makes those as well, but even those connect with a coarse thread screw. Pretty standard as far as dirt bike plug wires go.

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Two issues.

Clymer manuals are often full of errors.

Correct spec for the primary is .79 Ohms, +/- 15%, the secondary is 5.9k Ohms, also +/- 15%

Second, is to blame the coil or CDI when the most common issue is a bad stator/wire or switch. You make no mention of testing them.

The 'screw on' plug cap is a standard issue item. All bikes had them prior to COP.

 

I have a 1990 XT, over 30K on it, only parts (other than wear items) have been a turn signal relay and a cam chain tensioner. I have never had a single coli failure in my entire life (on thousands of bikes I worked on), nor have I ever had to replace the CDI. Many, many stators though.

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Jeeze, yeah right I guess it's my fault.  First think about who you're talking to, I have years experience fixing much better bikes.

I'm not buying the "clymer manual bad" excuse, I've found just as many inconsistencies coming from yamaha wiring charts, and other manuals.

I Tested the stator weeks ago, needed a new source coil - installed, needed a new regulator/rectifier, installed, lousy mechanic replaced control unit and ignition coil, both were not needed, 3 mechanics did nothing and all said "we're stumped" but lucky me I got to pay for it.  I tested all the switches months ago with homemade continuity tester, all OK.

It gets worse, broke apart the crap plastic housing on plug connector, a tiny spring connects a 1 inch gap between the wood screw and copper connector ON THE YAMAHA COIL. I KID YOU NOT.  The newest coil installed by mechanic - I chopped off the plug connector leaving as much wire as I could, Measured the resistance - Back to 4.2 kohms from 15 just like the others.

Anyone knows if the NGK wires are made the same way let me know, meanwhile soldering my own.

Edited by rotagen

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Quick update.  Cut through the crap plastic housing right at top of copper plug connector by measuring distance with nail.  Soldered the new coil directly after sizing some smalliish PVC tube.  Wrapped pvc with reflective heat tape.  Epoxied tube to housing after confirming that the secondary coil resistance was still 4.27 kohm after soldering direct. 

Connected to bike.  Started 2nd kick idled for short period and turned off.  Started 2nd kick again.  I have not had this in at least a year.  Before this mod, as in all year, I was lucky if the thing started in 12 kicks and it Never started again hot or even warm.  I'm a year older, a lot poorer, and a lot smarter when it comes to this crap bike.

Edited by rotagen

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