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78 CX500 Bobber.
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8 Posts
Discussion Starter · #1 ·
Long shot,but it just might work.
Is there anybody on this forum living in England close enough to Darwen nr Blackburn BB3 3PQ who would be willing to donate the CDI(the gold one) off there bike for 20 minutes,I need to do a quick swap to see if mine is knackered.
I have a 78 CX.
I will pay your fuel,cheers.
 

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1,752 Posts
Investigate an Ignitech replacement . It truly is plug and play - 15 minutes and you will be riding .
 

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'84 CX650E that is evolving into a GL500
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BTW: Don't forget to add your location and your bike's model and model year (NOT year first registered as your paperwork will show) to your profile as I asked you to 3 months ago.
 

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78 CX500 Bobber.
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8 Posts
Discussion Starter · #6 ·
Ok so I've done the above test to the best of my very limited electrical ability,my results are;
1/5-109
2/5-97
3/5-209
4/5-115
6/5-94
7/5-213,
9/5-417
9/8-no change on guage
8/gr-no change on guage
9/gr-417
5/gr-001
a/b-001
b/c-001
c/a-001
ABC/gr-no change on guage.
by "no change on guage",I mean the screen just read 1. and didn't throw up any other numbers as it did with the other tests.
So can anybody shed some light on this please,the right side isn't firing how it should.
 

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78 CX500 Bobber.
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8 Posts
Discussion Starter · #8 ·
The right side has a very weak spark.I've swapped the coils over and fitted new plugs/caps.Still no joy,the left downpipe is hot,the right is luke warm.If I pull the right cap the bike carries on running,if I pull the left it dies.
 

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Font Engineering Technology Screenshot Electric blue


That all seems good except for the absence of a reading on the high speed coil. 8 and 9 are linked together and grounded to the stator. I'm guessing the #8 wire has come adrift at its end from 9 and 5. This will give you a rev ceiling of around 5,000 RPM but should not effect only one side in the manner you describe.

Try swapping the ignition coils from left to right to see if the issue follows.. They are identical.
 

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1981 CX500C
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473 Posts
I wouldn't jump to the CDI yet.

To my knowledge, there is not a method to reliably test the CDI.

A good process is to test the other parts of the ignition system. If they all check within normal parameters, then the only thing left is the CDI.

Basic elimination.

Frankly, a more likely causes are the pulsars, stator, pickups, coils, plugs, resistors, connections.......

Dig out the wiring diagram. Follow the ignition circuits. Test one at a time. Be methodical. Record your readings.
 

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1981 CX500C
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473 Posts
Interesting conclusion.

Based on the OP's replies in posts #6, 8 and 10. The checks were the Stator test (#6), coil swap with plugs/caps (#8) and coil swap restated in (#10).
 

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Since the CDI is self generating and independent of the 12 volt system there can't be much else.

No pile on.

Just thought your post must have been going somewhere.
 

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1981 CX500C
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Granted, there isn't much to a CDI system.

Taking a risk of no pile-on....... because I have faith in CXPHREAK.

We know the Stator has some problems. We know the problem does not move with coil swap. We know plugs and caps are new. We know Lucky44 has limited experience with electrics (post #6).

Suggested earlier. Use the Wiring Diagram for the ignition system. Follow the wires from start to end testing for voltage and resistance. Record the numbers. Compare readings from the Left (working side) to the Right (failing side). Be methodical, like to the point of being anal retentive.

If the comparison between L & R is the same, then the only item left is the CDI box. At that point, a Finnbox (if available) is a cost effective solution that is plug & play.
 
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