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CB750C Cylinder 1&4 not firing.

Zoocrewsgarage

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I have swapped out the coils. I can fire both coils when hooked up to 2&3.
I can swap both spark ignitors TI . I have one, extra they all work on 2&3 cylinder side.
I can only fire the 2&3 cylinder from the pulsar.
Is there any other test i can do to rule out or confirm the 1&4 pickup is bad.
The only replacement is used parts?
Any help would be appreciated.
 
That sounds pretty definitive to me that it's an issue with the 1&4 timing pickup, but that doesn't rule out a wiring issue between that pickup and the spark units. I would check wiring continuity in a few places with a multimeter to make sure there's not, say, a cooked wire in the timing plate's pigtail.
 
I have swapped out the coils. I can fire both coils when hooked up to 2&3.
I can swap both spark ignitors TI . I have one, extra they all work on 2&3 cylinder side.
I can only fire the 2&3 cylinder from the pulsar.
Is there any other test i can do to rule out or confirm the 1&4 pickup is bad.
The only replacement is used parts?
Any help would be appreciated.
Did you resolve? What fixed it?
 
Pulse generator under left side cover. There are no new ones available. Have to source a used one. About $120-160. I checked everything switched coils and TI modules.
OK, Thanks Zoocrew. I replaced it, (assuming pulse generator = the OKI MPS-200) not my problem. Swapped and replaced.
Or perhaps you are referring to engine left side cover where the cdi 'pickups' are....
I apologize for possible nomenclature differences. I find different folks describe components by different names.
My actual problem is no, or too weak spark on 2-3. Found another post that seems to match my issue..
Have not had a chance yet to test his theory, but will....
 
OK, Thanks Zoocrew. I replaced it, (assuming pulse generator = the OKI MPS-200) not my problem. Swapped and replaced.
Or perhaps you are referring to engine left side cover where the cdi 'pickups' are....
I apologize for possible nomenclature differences. I find different folks describe components by different names.
My actual problem is no, or too weak spark on 2-3. Found another post that seems to match my issue..
Have not had a chance yet to test his theory, but will....
It’s inside the left cover on the engine . Controls ignition spark. And advance. Mine was bad. I only had Spark on 2-3 and not 1-4. There is also specs in the service manual online .
 
It’s inside the left cover on the engine . Controls ignition spark. And advance. Mine was bad. I only had Spark on 2-3 and not 1-4. There is also specs in the service manual online .
Hey Zoo, thank you for clarification. And thanks for the ebay link to view. Eby has been very handy for my '82 F.
 
I’m having a similar issue with cinder 2&3 not firing. There was a crack in the ignition coil to 2&3 so I replaced the ignition coils and still had the same issue. I’ve moved down to the electronic ignition and am thinking about replacing it with the Dyna electronic ignition. My concern comes down to the wiring. When I removed the original electronic ignition it has two blue wires and two yellow, but no black power wire. Any ideas on this?
 

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I’m having a similar issue with cinder 2&3 not firing. There was a crack in the ignition coil to 2&3 so I replaced the ignition coils and still had the same issue. I’ve moved down to the electronic ignition and am thinking about replacing it with the Dyna electronic ignition. My concern comes down to the wiring. When I removed the original electronic ignition it has two blue wires and two yellow, but no black power wire. Any ideas on this?
HI Jrapp,
I don't know the answer to your specific wiring question. But, I can tell you that I resolved my weak/no spark issue on 2 & 3 by adjusting the clearance spec on the cdi pulsar pickup that was aft (the one closer to front wheel was adjusted to spec, but the aft one was a much bigger gap).
I think the spec called for .015 " but check the service manual to be sure as my memory may not be accurate.
After this adjustment, checking spark with plugs removed and grounded, went from near imperceptible, to hot blue.
The only other change I made was to swap out my plug wires with some that came with a pair of coils I bought off ebay 9(the coils did not fix the proble, but the wires were NGKs, and my '82 F still had the originals.
Hope that helps.
 
I had to replace my pulsar to be able to get a signal
When you replaced it did you have any issues with the wiring? The one I currently have on has two yellow and two blue wires. All of the replacement parts I’m finding have one yellow, one blue, and one red. I know the red is to t in somewhere and get power but I’m confused on why the original part doesn’t have that and has duplicate yellow and blue wires instead
 
Looks to me like the 2 blues on the pick up go to the spark unit for cylinders 1/4, and the two yellow wires go to the spark unit for cylinders 2/3.
 
Looks to me like the 2 blues on the pick up go to the spark unit for cylinders 1/4, and the two yellow wires go to the spark unit for cylinders 2/3.
Yes, that is the case, but no black or red wire for power. I'm going to replace the spark units because cylinder 2&3 are not firing . The replacement part only has one blue and one yellow pickup. I was thinking I could just attach the single pickup wire to both feed wires. Does that seem accurate? Then follow Dynas suggestion for running a power wire.
 
This help?
 

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