Horrible ignition system

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Location: Devizes

Horrible ignition system

Post by CBX1000chris »

Hi everyone,

I've had my CBX for a few years now and it's always been a little slow to fire up on cylinders 2&5 and at tick over it was a bit lumpy. With a little time on my hands I decided to take a closer look.

Given it was only 2&5 that were playing I 'assumed' an ignition problem, OK it could be something else but I'm an optimist and I did rebuild the carbs a couple of years ago. The bike has an aftermarket ignition module fitted, I don't know the brand but it looks similar to the Electrex unit.

Having read a few threads on the forum I started with the ribbon cable and got a reading of 0.1 ohms from the connector to each coil for both the ground and signal wires. OK.

I then checked the coil primary windings and got a reading of 1.8/1.9 ohms for all coils. OK (I think).

I then measured the pick up coils and got a reading of 481 - 489 ohms so within specification. OK.

I then measured the coil secondary winding resistance by putting the meter probe inside the 1/6, 2/5 and 3/4 plug caps, basically the readings were all over the place but mostly infinity. Closer inspection showed most of the HT lead connections to the caps and coils were bad. OK - found something! (The HT must have been jumping the poor connections).

I unscrewed the cap on each of the coils and measured the secondary resistance again at the coil terminal, 1/6 was 11.19kohms, 2/5 was 17.95kohms and 3/4 was 11.30kohms. Looking more closely at the coils 1/6 and 3/4 are AW82 TR1 coils, 2/5 is unbranded. OK something else wrong.

I then measured the resistance of the plug caps:

1 - NGK Black - all over the place but generally about 45kohms
2 - NGK Brown - 4.94kohms
3 - Nichiwa Black - 4.83kohms
4 - Nichiwa - Black - 4.41kohms
5 - NKG Brown - 4.89kohms
6 - Nichiwa Black - 4.64kohms

I have no idea what the original fitment was but I suspect a new set of NGK Black 5kohm caps wouldn't go amiss!

There are AW82 TR1 coils available on eBay from about £25, looks as though Honda used them all over the place so a replacement shouldn't be a problem. However can anyone recommend a good source please. Also, I plan to replace all of the HT leads, is there a preferred brand for the CBX?

Is there anything else I should check while the ignition is in bits?

Thank you in advance,

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Re: Horrible ignition system

Post by shiskowd »

Chris - the resistor caps deteriorate with time and should be replaced. On a low mileage pro-link that I’m bringing back to life all 6 resistor caps were ‘open’. On a ‘79 Z that I brought back to life last year I purchased on eBay a coil set for a ‘97 Gold Wing for like $45.. The coils are a differing size but can be fitted to work and the high tension leads are long enough to cut down to length w/ new resistor caps (look for NGK SD-05F, also from various eBay sites).
2010 KTM 690 Enduro Rally, 1982 Pro-Link (resto in progress), 1979 CBX 'Z, 1975 Moto Guzzi 850T
Long Sleeping '79 CBX Restoration > viewtopic.php?f=102&t=11699

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