I managed to get power into the ignition system, The engine is turning, however all sparks are very weak.
I don't want to change the ignition system for dyna etc. unless absolutely necessary, mainly because I am not well up on electrics.
Any advice. Ohm readings to High and low tension coils are all within the range in the manual.
Thanks in advance.
P
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Weak spark
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Re: Weak spark
Got good earth's?
Pete
Pete
- warren3200gt
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Re: Weak spark
Are you on points or khi electronic?
If points are they crappy Chinese replacement condensers and points I've seen and replaced so many of these causing issues. Also crappy fake plugs give weak sparks.
Feed to coils 12v +?
As Pete says engine earth needs to be good also.
Although your not keen to swop to Dyna they are very simple to fit and then are fit and forget.
If points are they crappy Chinese replacement condensers and points I've seen and replaced so many of these causing issues. Also crappy fake plugs give weak sparks.
Feed to coils 12v +?
As Pete says engine earth needs to be good also.
Although your not keen to swop to Dyna they are very simple to fit and then are fit and forget.
Last edited by warren3200gt on Fri Feb 25, 2022 2:43 pm, edited 1 time in total.
PUM 488 June 2026
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
Re: Weak spark
try this ... it has its critics and followers , what do you have to lose

Keith

You can never have too many tools in your life, except the two legged variety
I'm never wrong, once I thought I was but I was
mistaken.
Phil Churchett winner 2013


You can never have too many tools in your life, except the two legged variety
I'm never wrong, once I thought I was but I was
mistaken.
Phil Churchett winner 2013
Re: Weak spark
Skid Mark wrote:I managed to get power into the ignition system, The engine is turning, however all sparks are very weak.
I don't want to change the ignition system for dyna etc. unless absolutely necessary, mainly because I am not well up on electrics.
Any advice. Ohm readings to High and low tension coils are all within the range in the manual.
Thanks in advance.
P
Recently had the same thing and thoughts - had a weak spark and the A4 wouldn't start. Checked, cleaned, regapped and multimeter'd everything; coils and points good, but changed the condenser pack (which I didn't need to do). Tested the plugs (B8ES) and all four had poor continuity and high resistance (20k+) even though they still sparked.
Swapped them out for a new set and the old girl fired up on the first prod!
Current Bikes:
Phil Churchett's 1976 Z900 A4: PRE 2R https://www.flickr.com/photos/115740825@N05/albums/72157680116996884
1973 XL250 K0 Motosport: UKX 73L
2023 R1250 GSA
Previous Zeds: Z750B1 Twin, Z650B1, Z750E
Phil Churchett's 1976 Z900 A4: PRE 2R https://www.flickr.com/photos/115740825@N05/albums/72157680116996884
1973 XL250 K0 Motosport: UKX 73L
2023 R1250 GSA
Previous Zeds: Z750B1 Twin, Z650B1, Z750E
Re: Weak spark
Thanks for the replies,
I appear to have a good earth at the engine. I should have said its A 1000r with original CDI ignition.
Modifying the coil feed does look tempting at the minute, but I'll persist a little bit longer before I go pulling out the loom...again. The plugs are B8ES, I have read that there are knock off NGK's being sold on the web but I though buying from a motor factors would be a safe bet and as I checked the spark with a champion plug I found on a shelf ( brand new). So it's unlikely to be the plugs but worth a look.
please keep the advise coming!
P
I appear to have a good earth at the engine. I should have said its A 1000r with original CDI ignition.
Modifying the coil feed does look tempting at the minute, but I'll persist a little bit longer before I go pulling out the loom...again. The plugs are B8ES, I have read that there are knock off NGK's being sold on the web but I though buying from a motor factors would be a safe bet and as I checked the spark with a champion plug I found on a shelf ( brand new). So it's unlikely to be the plugs but worth a look.
please keep the advise coming!
P
Re: Weak spark
make sure you have got battery voltage in the yellow/red wire at the cdi
Re: Weak spark
Hi again,
I cleaned the engine earth again and charged the battery over night. I soldered a tubeless insert into a thinners can and connected to the carbs and topped up with petrol. Plan was to just try start it as is, before doing anything drastic. I Pressed the starter and... it frightened the SH!TE out a me!! it fired almost immediately, after nearly 20 years! I then realised flames from the exhaust ports were licking the oil cooler, so I shut it down, but I am one happy bunny today! I need a hand to get it off the lift before I can fit the exhaust, that will be on Monday. Thanks for all the replies.

I cleaned the engine earth again and charged the battery over night. I soldered a tubeless insert into a thinners can and connected to the carbs and topped up with petrol. Plan was to just try start it as is, before doing anything drastic. I Pressed the starter and... it frightened the SH!TE out a me!! it fired almost immediately, after nearly 20 years! I then realised flames from the exhaust ports were licking the oil cooler, so I shut it down, but I am one happy bunny today! I need a hand to get it off the lift before I can fit the exhaust, that will be on Monday. Thanks for all the replies.


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