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Discussion Starter · #1 ·
hey everyone! this is my first post - hope you guys have some ideas.



a buddy and I have picked up an '81 cx500 deluxe. it's running ok in low rpm range, but we can't get it to rev past 4500 or 5000 rpm either in neutral nor under load.



the shop we picked it up from said these are notorious for needing a new pulser I think they called it - fits behind the rear engine cover. however, the problem sounds and feels like a fuel delivery problem to me. it will rev smoothly up to about 4500, then stumble and back off like it's not getting gas.



does this sound like a common problem? if so, is the new pulser (or whatever) probably the culprit?



thanks much!

ron
 

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Hi Ron

If its a CDI ignition bike many here will be muttering

"Stator failure"

On CDI bikes, the generator in the back of engine sacrifices some

charging coil space to use 2 coils for powering the CDI igntion

these have been the bane of many a CX



I'd suggest doing a stator resistance test first

terminals 8 and 9 are the usual suspects

Do the tests and see how you go from there

 

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Reg is correct on the first step. If you get reasonable reads from this test, then check the voltage coming from the stator on the blue wire and the white wire. These will be AC voltages, set your meter appropriately. The white is the low speed winding and should be around 90 volts, the blue (high speed winding) should be a bit higher.



This brings up the "white wire fix". That is when the high speed coil has gone out and you share the white coil output with the blue wire going into the CDI. This allows enough voltage to power the CDI's high speed circuit for operation past the 5000 RPM level. It is not a permanent fix, but can be helpful in tracking down problems.



Another possible area would be if the PO has had the carbs off and reversed one or both side's jets. The higher number (written on the side of the jet cap), should go into the brass hex fitting. That happened to me, and it would not go over 55 MPH.
 

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The output tests on the blue and white wires that Blue fox referred to are done while the engine is cranking over on the starter, or you'll get zip. Be kind, pull the plugs first.
 

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As a side note, there is currently a group buy going for the Ignitech CDI replacement. Should your stator check out failing on those tests, this item will eliminate the issue for you. Check the selling/buying section for more info.



Joel in the Couve
 

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Something else to check is the jets. When I first got my bike I discovered that the high and low jets were backwards in one carb and it caused a similar problem.
 

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Discussion Starter · #9 ·


ok, here's our test results:

1/5 = 122

2/5 = 100

3/5 = 225

4/5 = 116

6/5 = 98

7/5 = 221

8/9 = 158

5/9 = 522



5/White = 60 ACVolts

5/Blue = 78 ACVolts



OK, so who can tell me what all that means?
if i'm reading it right, my source coil is mesed up and the RH lowspeed coil is, as well. is that right?





We replaced the almost-broken ground connector on the CDI box tonite. I also did the following:

--rebuilt the petcock

--replaced spark plugs

--replaced main fuel line

--replaced air filter

--filled the tank with fresh gas & a couple ounces of Marvel Mystery Oil



At this point, I can occasionally coax it to rev up around 9000rpm. Even then, it's rough from 4500 on up. **EDIT: this is only on the centerstand - under load, it won't rev past 4500...**



So what's next? I have coils and ignitors from an '82, but the wiring looks different. Is there any way to use those coils?



Oh, and it looks like the LH coil was replaced with one from a '78 model. Should I try new coils?



I haven't taken the carbs off, but that will probably happen soon.



Thanks in advance for any advice on what to try next!

Ron
 

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'78 coil should work the same as '81, both being CDI.



The '82 coils however are for use with a different type of ignition system and therefore I don't think you can use them. Reg or someone more up on the electronic side of things can verify this for you as to be honest I've not tried it.



Cheap CDI coils are available on ebay. I've just bought 4 of these, - around $11 each delivered to my door and I reckon Shep will be able to give you the link for these.



The stator tests above seem to be fairly normal except the 8/9 and 5/9 tests, both being higher resistance than they should be.



To the electronics intelligentsia, - while not shown here I was wondering why there is no 8/5 test shown here. Every other wire here is tested against #5 [the earth] but not the high speed coil which is probably the item of interest here. Could this be an oversight with the manual or am I just tripping?
 

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Discussion Starter · #11 ·
can anyone help me interpret the above results? i'm assuming since some resistances are way too high, i need a new stator or one of the Ignitech CDI boxes. am i right?



thanks!

ron
 

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To the electronics intelligentsia, - while not shown here I was wondering why there is no 8/5 test shown here. Every other wire here is tested against #5 [the earth] but not the high speed coil which is probably the item of interest here. Could this be an oversight with the manual or am I just tripping?


CXPHREAK,,, I don't include myself in the electronics intelligentsia,,but see my post in this thread.
 

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can anyone help me interpret the above results? i'm assuming since some resistances are way too high, i need a new stator or one of the Ignitech CDI boxes. am i right?



thanks!

ron


Ron, you may have a bad stator. The numbers are borderline. Chances are if you don't need one now, you soon will.




I think if I were you I would try cleaning the carbs though before I pulled the engine and replaced the stator. It will eliminate another possible cause of your problem and is something that probably should be done anyway. Make sure both slides are operating smoothly.



Are you positive you have the vacuum line on the correct outlet on the petcock,,it goes to the one closest to the front of the bike?



Also if you could find another CDI to try it would also narrow down the possible causes. If you let us know where you are located there may be someone nearby that would let you swap theirs to rule it out.
 

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Discussion Starter · #14 ·
i'll pull the carbs and see what i find.



i'm north of Oklahoma City, in Edmond, OK. if someone would let me try their CDI/coils that would be fantastic!



thanks, all

ron
 

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Now would also be a good time to try that "white wire fix" method. if it run then, you found your problem.
 

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Now would also be a good time to try that "white wire fix" method. if it run then, you found your problem.


I thought about mentioning it,,but he has less voltage on the white wire than the blue,,so I didn't know if it would help.
 

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I thought about mentioning it,,but he has less voltage on the white wire than the blue,,so I didn't know if it would help.
It's worth a shot IMO. The no -load voltage doesn't tell you what it would behave like under load.. Under load that high resistance might just translate into lower current available.
 

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Good point,,electrical is not my strong suit.
 

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Or maybe I'm completely mistaken
 

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Discussion Starter · #20 ·
ok, here's an update:



last night i pulled the carbs and i've never seen cleaner carbs! they have obviously had carb kits installed recently. the jets are new (and in the right positions), new needles, etc... so that's not my problem!



i ordered a couple new coils from eBay, so we'll see if it's that easy.



i also PM'd to get in on the ignitech CDI group buy, but i may be too late, not sure. can y'all help me be sure i understand this - if my stator is charging OK, (and it is) i can stick with it and just go with the ignitech CDI and be fine, right? has anyone had experience with doing that, then their stator died completely? is that where i would be able to go with the cheaper G7 (or whatever) stator that i read about on another thread? thanks! i think i'm getting this, but just wanted to be sure.



i found a stator on eBay for like $215, and i called custom rewind and they quoted me $240.



thanks, all! about to flush the radiator now. i love this thing!

ron
 
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