Topic: 2-3 Cylinder Stopped Firing Mid Ride

[abaksa]

So my 2-3 cylinders aren't firing anymore. 1-4 are firing just fine. I'm not super savvy with the bikes, but my buddy who's done all the work on it is very good at what he does, just has a heavy work load so I've been trying to figure this out on my own and need some help. A little background, it's a 74 CB750, brand new PAMCO ignition system with upgraded high-output coils, new plug wires that were recommended with the coils, brand new rectifier and stator. I was out riding, not going crazy but was giving it some power, and all of a sudden 2-3 cylinders stopped firing. I checked plugs, and they're not fouled. I switched the left coil to the right and it worked fine, so I don't think it's a coil issue, unless I'm missing something. I checked the power to each coil wire using a meter and both black and red wires are getting power, but the coil isn't outputting a spark. I've tried trimming the plug wires and screwing them back into the coil tight and still nothing. Not sure what else to try and check, anybody have any ideas? Could it be one of the motherboards on the ignition has gone bad?

Your advice would be greatly appreciated. Sorry for such a long post.

[WaleFab]

Is it a sporadic issue or constantly misfiring and you can't get it running proper anymore?

[abaksa]

WaleFab, it's not a sporadic issue, it's only happened once and now I can't get those cylinders to fire anymore, and can't for the life of me figure out what is going on.

Thanks for Pete's info Calj737, I've been trying to contact him thinking it was an issue with my ignition. I checked the crimping and it all looked good, but I'll double check again. I was thinking it might be a grounding issue too, but checked my grounds and things checked out. I did however notice that I'm getting voltage from the black wire to the left coils, isn't that suppose to be the ground and shouldn't be hot?

[abaksa]

Ok, that's some good information, I wasn't sure how it all worked exactly, like I said I'm not entirely savvy, but I can do some stuff with a little bit of direction. I'll post up a picture later today, hopefully that will give everyone a better idea of how it's setup.

[abaksa]

Oh and my coils were bought from Cb750supply, along with the  PAMCO kit.

[Deltarider]

I'm sorry to be the one to break this news to you, but those 2.5Ohm coils are not really suitable for your bike. They create a significant electrical draw on your charging system. Stock is designed for 5.0Ohms. Even folks who run 3.0Ohms struggle.

The issue here is not so much the charging system as well as the charging of the coil. If (if) Pamco's is designed to run with 5Ω coils, 2,5Ω coils will have too much and will be damaged after some time unless another (supplied?) cam (or programming) is used that reduces the dwell period or even a ballast resistor to cut the current. Some suppliers of electronic ignitions ask you to specify whether you're going to use the set in combination with 5Ω coils or 3Ω coils, so they can send you the right cam. I suggest you to contact Pamco on this. If what I presumed above happens to be true, coil 1+4 runs the risk to be damaged too.

[70CB750]

Did you get the Ultimate Pamco Ignition Kit from Vintage?    I used that set in Dorothy for 25 000 miles with 0 issues.

[abaksa]

Did you get the Ultimate Pamco Ignition Kit from Vintage?    I used that set in Dorothy for 25 000 miles with 0 issues.

I bought the basic PAMCO kit, but basically was the ultimate kit, because I bought the Honda CB750 High Output Ignition Coils and the upgraded plug cables too, so it was the same as the Ultimate Kit, just purchased each item individually.

[abaksa]

I'm sorry to be the one to break this news to you, but those 2.5Ohm coils are not really suitable for your bike. They create a significant electrical draw on your charging system. Stock is designed for 5.0Ohms. Even folks who run 3.0Ohms struggle.

The issue here is not so much the charging. If Pamco's is designed to run with 5Ω coils, 2,5Ω coils will have too much and will be damaged after some time unless another (supplied?) cam is used that reduces the dwell. Some suppliers of electronic ignitions ask you to specify whether you're going to use the set in combination with 5Ω coils or 3Ω coils so they can send you the right cam.

I have no problem switching back to stock style coils if that would fix the issue. It's odd though that CB750 would recommend the high output coils though with the PAMCO ignition if it was known to cause issues?

[70CB750]

I was wondering that too.

Why dont you measure the resistance of your coils? I mean what Cal says about resistance is a valid problem.  My coils are boxed away, since Dorothy awaits a rebuild, but most important is to find whats wrong with your bike.

I dont think it would quit firing in such a short time even with the coil resistance being low.  Send a PM to Pamcopete, he will help you troubleshoot.

[Deltarider]

Words like 'ultimate' and 'high output' have little or no significance I'm afraid. Contact Pamco to verify if the basic kit can be combined with 2,5Ω coils or extra measures have to be taken to reduce the current to the coils.

[abaksa]

I was wondering that too.

Why dont you measure the resistance of your coils? I mean what Cal says about resistance is a valid problem.  My coils are boxed away, since Dorothy awaits a rebuild, but most important is to find whats wrong with your bike.

I dont think it would quit firing in such a short time even with the coil resistance being low.  Send a PM to Pamcopete, he will help you troubleshoot.

I sent him a message, awaiting his reply. I measured the resistance, by putting the leads on either end of the coil and got around 3.5 or somewhere around there, if I can remember correctly. I think that was the way to do it?  I'm wondering why one would fire just fine, and the other not, even when I switched it, the 2/3 coil fired perfectly fine in the 1/4 position coil, so maybe a wiring issue. But again, I'll see how Pete has to say about it, but thank you for your advice.

[Deltarider]

I'm wondering why one would fire just fine, and the other not, even when I switched it, the 2/3 coil fired perfectly fine in the 1/4 position coil, so maybe a wiring issue.

Ooops, sorry, I missed that.

[abaksa]

Here's some pictures, I don't know if these will be helpful or not.

[Deltarider]

In the top pic I see HT leads that are very close to (in fact touching it seems) the frame (= ground!). I would avoid that to prevent possible arcing there.

[abaksa]

In the top pic I see HT leads that are very close to (in fact touching it seems) the frame (= ground!). I would avoid that to prevent possible arcing there.

Where's that on the photo again? Sorry I'm having trouble seeing it...

[flybox1]

Exposed copper there on the black to yellow, and unraveling electrical tape = potential troubles.
Soldering+shrink tubing kits will run you less than $20, and last a lifetime.

[abaksa]

Exposed copper there on the black to yellow, and unraveling electrical tape = potential troubles.
Soldering+shrink tubing kits will run you less than $20, and last a lifetime.

Yeah, that was together before and shrink-wrapped. I have it apart temporarily because I'm going to redo the connection, I probably should have mentioned that.

[abaksa]

Checked all wires and grounds and everything looks sound and solid and still no spark from coil...any other suggestions? I'd hate buy the stock style @ 5ohms and have it not make a difference.

[Honda550k]

Did you check for spark on 2 and 3?

Sent from my LG-H812 using Tapatalk

[abaksa]

Did you check for spark on 2 and 3?

Sent from my LG-H812 using Tapatalk

I'm not getting a spark on 2&3 plug wires, but I'm getting the correct power to the coils, and I've tested the coil on the right side and it fired fine. I spoke with Pete from PAMCO and was told to do a test on the green and red wires on the actual PAMCO board to see if those are running correctly, if not he's going to send me replacement due to a failed board. Hopefully this is the root of the issue as I can't seem to find any other reason why it would be doing this. Will keep everyone updated, and thank you again to everyone who has submitted a reply, it's definitely helped me work through possible issues.

[abaksa]

Anybody know a good way to contact pamcopete? I PM'd him and he told me to do the test on the board and it came back with negative results, so I sent those to him and I haven't heard from him in over a week... I've PM'd him multiple times in hope for a response.

[abaksa]

Awesome. Thank you so much! I really appreciate it. Based on the readings I got from my board, I think I found my problem. So hopefully a new board and I'll be out riding again soon!

[Scott S]

 The good news is that Pete is happy and healthy.

 The bad news is, he had some problems on the supply side just as huge orders came in. Something out of his control. He's using new units to try and cover warranty claims and is simply swamped right now.
 He said to tell everyone Thanks and that he's getting to stuff as quickly as possible.

 On a side note....and this is me speaking personally.....how many electrical items come with ANY warranty at all? I think everything I've ever purchased says "no warranty, no returns on electrical items".  Ever tried to get a Dyna replaced under warranty? After several weeks or even months? Hell, just try to get their customer service to respond.
 I know for a FACT that Pete has replaced units at his expense that were destroyed 100% by the end users faultiness.
I'm grateful for his participation in our hobby.

[70CB750]

 I know for a FACT that Pete has replaced units at his expense that were destroyed 100% by the end users faultiness.

Yes, I remember that.

[abaksa]

The good news is that Pete is happy and healthy.

 The bad news is, he had some problems on the supply side just as huge orders came in. Something out of his control. He's using new units to try and cover warranty claims and is simply swamped right now.
 He said to tell everyone Thanks and that he's getting to stuff as quickly as possible.

 On a side note....and this is me speaking personally.....how many electrical items come with ANY warranty at all? I think everything I've ever purchased says "no warranty, no returns on electrical items".  Ever tried to get a Dyna replaced under warranty? After several weeks or even months? Hell, just try to get their customer service to respond.
 I know for a FACT that Pete has replaced units at his expense that were destroyed 100% by the end users faultiness.
I'm grateful for his participation in our hobby.

Thank you Scott for the update. I will wait patiently for his response. I can't imagine how swamped he is on a regular basis, not to mention when issues arise with supplies. I'm definitely grateful for the warranty and for everyone's help with this issue.

[70CB750]

I actually have Pamco from Dorothy boxed in storage, you are in Lancaster, if I ship it you could have it next week and when you get a replacement from Pete, you would just send it back to me.

I will not need it for year or more.

Let me know 

[NoLuck]

Sounds like we are having the same issue. I ordered new coils plugs and caps hoping this fix the no spark issue with my 2 and 3 plugs

[abaksa]

I actually have Pamco from Dorothy boxed in storage, you are in Lancaster, if I ship it you could have it next week and when you get a replacement from Pete, you would just send it back to me.

I will not need it for year or more.

Let me know 

I really appreciate it that, but I just wouldn't feel right taking the responsibility of someone else PAMCO, I'd hate for anything to go wrong. But thank you, that's really nice of you. I can make a couple more weeks, hopefully everything will be sorted out by then.

[abaksa]

Sounds like we are having the same issue. I ordered new coils plugs and caps hoping this fix the no spark issue with my 2 and 3 plugs

It's a frustrating problem, I almost did the same thing, but after testing my coils, they came up fine. I switched my left one to the right position and it fired the 1-4 cylinder just fine. I also switched plug wires from 1 to 2 position, and the #2 plug wire gave a spark on the #1 position, so that ruled that part out. Hopefully it's not your ignition system. What PamcoPete told me to do was to test the red and green wires that go from that coil to the ignition board. Per his instructions, the green wire should read at 12V and once the ignition button is hit and engine starts to turn, it should make its way around 0V. You may know this already, but just thought I'd pass along anything that I learned during this fix.

[abaksa]

Sounds like we are having the same issue. I ordered new coils plugs and caps hoping this fix the no spark issue with my 2 and 3 plugs

It's a frustrating problem, I almost did the same thing, but after testing my coils, they came up fine. I switched my left one to the right position and it fired the 1-4 cylinder just fine. I also switched plug wires from 1 to 2 position, and the #2 plug wire gave a spark on the #1 position, so that ruled that part out. Hopefully it's not your ignition system. What PamcoPete told me to do was to test the red and green wires that go from that coil to the ignition board. Per his instructions, the green wire should read at 12V and once the ignition button is hit and engine starts to turn, it should make its way around 0V. You may know this already, but just thought I'd pass along anything that I learned during this fix.

His problem is rather different. He has a Dyna S and 2 different coils. So his non-firing coil is due to being a 3Ohm mixed with a 5Ohm.

Oh ok, I see. Then my advice is useless in this case haha.

[abaksa]

Thanks everyone for their help. Pete is sending me a new unit under the warranty. Should be back and running in no time!

Aaron

[abaksa]

New ignition thanks to Pete, and all cylinders firing beautifully. PROBLEM SOLVED! Thanks Pete for such great service.

Aaron

[70CB750]

Great!