Author Topic: Aftermarket Coils  (Read 261 times)

Offline philward

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Aftermarket Coils
« on: March 25, 2020, 07:19:46 PM »
Whats caused this! Bought these from M&P and haven't started bike yet. I've been manually timing project K6 and heard a 'sizzling' - took tank off to discover this (coil was to not to touch. Checked connections and aftermarket coil yellow connected to points and black to black. The other coil is connected the same and no issues. Only time I've had ignition on is during testing of rest of electrics - maybe max 10 mins at a time
Is it just a duff coil?
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Offline Bryanj

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Re: Aftermarket Coils
« Reply #1 on: March 25, 2020, 07:24:39 PM »
I would say yes

Offline Rob62

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Re: Aftermarket Coils
« Reply #2 on: March 25, 2020, 07:50:09 PM »
If you’re only testing the rest of the electrics, leave the kill switch off...

Offline philward

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Re: Aftermarket Coils
« Reply #3 on: March 25, 2020, 07:57:41 PM »
If you’re only testing the rest of the electrics, leave the kill switch off...
Never thought of that Rob! Simples!
Current Bikes:-
Kawasaki ZZR1100D3
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Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)
Honda CB500K2 (1973) Project

Offline Moorey

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Re: Aftermarket Coils
« Reply #4 on: March 25, 2020, 08:04:14 PM »
Duff coil the other one has been energized just as long and that's fine.

Offline Bryanj

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Re: Aftermarket Coils
« Reply #5 on: March 25, 2020, 08:51:14 PM »
Not necessarily maybe only 1 set of points were closed

Offline AshimotoK0

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Re: Aftermarket Coils
« Reply #6 on: March 25, 2020, 09:18:26 PM »
Probably a low resistance coil design. It's all about Amp/Turns .. they probably reduced the number of turns of the coil to decrease resistance in order to save the cost of copper but still get the same magnetic flux. Unfortunately,  that vastly reduces the 'duty-cycle' ... meaning if you leave the coil energised  for a long period it is likely to suffer burnt out windings. Never really seen that happen on a genuine Nippon Denso coil (typical DC resistance of a Denso coil is typically around 4.5 ohms). It's different with a CDi system coil as they can be low resistance and low duty cycle because they can never experience long term continuous current flow in normal use or when the engine is static but the ignition is switched on.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Moorey

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Re: Aftermarket Coils
« Reply #7 on: March 25, 2020, 09:33:51 PM »
Not necessarily maybe only 1 set of points were closed

Quite true.

Offline philward

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Re: Aftermarket Coils
« Reply #8 on: March 25, 2020, 09:42:48 PM »
All very interesting - I've emailed M&P for a relacement. Will be careful in short term and recon a std set as per James method before I sell the bike
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)
Honda CB500K2 (1973) Project

Offline gtmdriver

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Re: Aftermarket Coils
« Reply #9 on: March 26, 2020, 11:27:13 AM »
Make sure that the coils have the same primary resistance as the originals. (3 -4 ohm).

Coils designed for use with electronic ignition systems have a very low resistance (1.5 ohm) so when the points are shut twice the current will be flowing through the system. I'm not saying that was the reason for your failure but if you fit the wrong coils the points will burn very quickly and you could damage the condensers.

Offline AshimotoK0

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Re: Aftermarket Coils
« Reply #10 on: March 26, 2020, 01:20:10 PM »
All very interesting - I've emailed M&P for a relacement. Will be careful in short term and recon a std set as per James method before I sell the bike

You could also try the Ashimoto method too Phil.  ;D
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Johnwebley

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Re: Aftermarket Coils
« Reply #11 on: March 26, 2020, 01:46:16 PM »


  not having the skill to do the Ashimoto fix,and running Boyer ignition  ,after my original packed up because of old age and cracked hard HT leads,I bought Silvers coils,they got hot and failed after about 12 months,
so I spent a little extra,and purchased Boyer compantable coils .

 now several years later,still working great
lifelong motorcycle rider,and fan

Offline philward

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Re: Aftermarket Coils
« Reply #12 on: March 26, 2020, 10:19:01 PM »
All very interesting - I've emailed M&P for a relacement. Will be careful in short term and recon a std set as per James method before I sell the bike

You could also try the Ashimoto method too Phil.  ;D
I will be going that route Ash - I run the same coils on my std K2 and checked the resistence when I fitted them and they were 3 - 4 ohms.
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)
Honda CB500K2 (1973) Project

 

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