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Sudden loss aof spark

  • Thread starter Thread starter machinest
  • Start date Start date
M

machinest

Guest
1980 550L
I was riding back from work today and about halfway home the bike loses power doing 55 and all of a sudden the bike will only do about 40 with full throttle . limp the bike home and start to check things ,pipes from cylinders 1&4 are cool (right hand coil ), pull seat and tank off and check wiring all seems good mess with bike for a wile and get some life but at end only two cylinders firing . tomorrow after work will check all wiring between ignition and coil . My question is can a coil fail all of a sudden and is there a way to check for a bad coil.

work done on bike
Carbs pulled dipped and O rings replaced
Coil relay mod
Valve clearance done
carbs synced
all electrical connectors cleaned or upgraded
petcock replaced
RR replaced and rewired (PO mod)
 
I think a coil could indeed just up & fail, especially if heat is involved. You can check the coil with an ohmn meter with the key off, should read about 30-50K on the primary side, and about 5 on the secondary (as I remember, could have that backwards).

Check the plug caps - they are known for corrosion issues resulting in limited/no spark.

A good upgrade is the dyna-coils, looking at about $125 from Z1.

good luck.
 
Since you did the coil relay mod do you have +12 at the suspect coil ? Pull a plug from that coil with the plug wire connected and ground it, then with the +12 on 1 side of the coil pull the other wire and connect a jumper wire to it, ground and unground the jumper doing this the plug should spark . No spark and the coil or plug wire are bad.
 
Played with the coils some and replaced one bad coil but no improvement or rather temporary improvement bike ran OK until it warmed up then two cylinders cut out (1&4) got it home and no spark to those two plugs swapped the coils over (input & output) and the same situation occurred so its not the coils .Can half the igniter box fail or is it a all or nothing type thing . also may try replacing the connector between the pickups on the end of the crank and the harness proper as it is one of the few connectors I only cleaned as I would have to splice in extra wire to get it to fit,
 
Time for a Dyna Ign. The ignitor is probably failing when it get hot
 
This may sound like a silly question but is the Dyna S a complete stand alone unit or dose it use the cdi box on the bike.
 
It replaces the ignitor. I believe there are two types of Dyna ignitions - one to replace the OEM Nippon Denso (ND) points plate & one for the other OEM points plate (KD).

Pull the points cover off & look for the marking (NP or KD) on the plate. Then call Z1 & buy the appropiate one. Rob at Z1 will walk you through the process.

http://www.z1enterprises.com/catalog.aspx?pid=MFDY2

Good luck
 
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