Follyworks Posted January 31, 2009 Share Posted January 31, 2009 Ever since I got this bike (a 78 xs400e), it's been reluctant to start - nursing either the electric start or the kickstart, it would only grudgingly start up - once running, it seemed to run well, just not wanting to start up. So I went through all the obvious stuff - yes, it had spark, yep, charged battery. Hey, even good compression! Clean carbs, and once it starts, it seemed the air/fuel mix was decent. But especially with the colder weather, starting the little beast was becoming impossible. Went through the whole checklist again today, and decided that, while it was giving a visible spark, was it a "fat" spark? So decided to run through the ignition system. Battery? Fully charged and actually read as 13.1 volts Plugs? Good condition, properly gapped, but only giving a thin blue spark when I try the ignition. Points? Look real good, and gaps seem right. So pulled the gas tank off to test the coils. Check the Haynes manual, free up the appropriate wires, and stick the meter on it. Right Coil, primary circuit - 4.0 ohms. Dead on factory spec, and I'm thinking I've pulled the gas tank for nothing. But then test the secondary circuit, and got 4.38M ohms. That's a capital M, telling me that instead of the 9,000 ohms I was expecting, it says 4,380,000 ohms. Obviously, a bit off from spec. The other coil, not nearly as bad, but still off by a ways (3.8 ohms primary, 17.6k ohms secondary). This seems like my most likely culprit on weak starting now (though, once started, it's been running fine, which seems odd if the coils are that far off spec). I can find OEM coils for about $100, which seems excessive given what I paid for the bike, or ones on Mike's XS650 that say they're the same primary ohms, but look like a completely different shape and mounting methods. Anyone able to tell me whether those will work on my xs400, or give me a different source for affordable ones that match my originals? Link to comment Share on other sites More sharing options...
JimR Posted January 31, 2009 Share Posted January 31, 2009 Ever since I got this bike (a 78 xs400e), it's been reluctant to start - nursing either the electric start or the kickstart, it would only grudgingly start up - once running, it seemed to run well, just not wanting to start up. So I went through all the obvious stuff - yes, it had spark, yep, charged battery. Hey, even good compression! Clean carbs, and once it starts, it seemed the air/fuel mix was decent. But especially with the colder weather, starting the little beast was becoming impossible. Went through the whole checklist again today, and decided that, while it was giving a visible spark, was it a "fat" spark? So decided to run through the ignition system. Battery? Fully charged and actually read as 13.1 volts Plugs? Good condition, properly gapped, but only giving a thin blue spark when I try the ignition. Points? Look real good, and gaps seem right. So pulled the gas tank off to test the coils. Check the Haynes manual, free up the appropriate wires, and stick the meter on it. Right Coil, primary circuit - 4.0 ohms. Dead on factory spec, and I'm thinking I've pulled the gas tank for nothing. Hi I would try setting the dwell angle, 22.5% , and setting the tappits & timming then balance the carbs this alway seemed to fix bad starting problems Regards Jim Link to comment Share on other sites More sharing options...
Follyworks Posted February 2, 2009 Author Share Posted February 2, 2009 I can see I gave too much info, and buried my actual question - though those are some of the steps I'm working though on the starting problems, Jim. Ignition coil, supposed to test at 4 ohms resistance primary circuit, 9k ohms secondary circuit. Mine test at 4 ohms primary circuit, 4.4M ohms on the secondary on the right side coil, and 3.8 ohms primary and 17k ohms on the secondary for the left side coil. Obviously, the coils are not performing at or near spec - what problems can I attribute to this, should these be replaced, and can anyone tell my a good and affordable source for them if I should be replacing them? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 4, 2009 Moderator Share Posted February 4, 2009 try http://www.motorcycle-ignition.com/motorcycle_coils.htm I bought these http://www.rexcauntracing.com/pages/htcoils.html partsnmore in us of a Link to comment Share on other sites More sharing options...
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