Author Topic: No spark on Cylinders 2 & 3 (Read 8700 times)

GreenMachine · « **on:** May 12, 2012, 01:17:53 PM »

Hi everyone. This is my first post. Need a little help. My first bike (got it last summer), a 76 Honda CB550, began having problems about a week ago. After riding approx 15 minutes or so, I came to a traffic light, and there I noticed the engine was no longer able to hold its idle (had to keep the RPMs up to keep the engine from dying). Needless to say, after checking my idle, petcock, etc. I turned the bike around and came home. I was unable to determine the problem. Then a few days later I tried starting it up and despite how much throttle I gave it, I could not keep the bike running (it starts, but runs only for a short while). I checked for gas in each of the carb bowls via the drain and there was clean fuel in each. I also have checked the fuel lines into the carb and no obstructions were found. Gas appears to flow from both valves of the petcock as well. I then checked for spark on all 4 cylinders and numbers 1 & 4 have spark but numbers 2 & 3 do not. The spark plug tips, by the way, were indicative of a very rich mixture (black in color). I have since puchased and installed 4 new spark plugs, but still no spark on 2 & 3.

Anyway, I purchased a multimeter and have checked both the right and left side of the Dyna coil. The multimeter reads exactly 3 ohms for each side of the coil which lines up to what is printed on each side of the Dyna coil (3 ohms). I have checked the spark plug cables from a continuity perspective with the multimeter and all appear to test fine. I have inspected visually all of the wires from the Dyna coil to the Dyna ignition and all appear to be intact (it was only a cursory review). Not sure what to check for next. If I only knew what the problem was, I could just fix it! Sadly, however, I am stumped. I have not been riding / working on bikes very long, so my experience level is very low, but I can read and follow direction well :-) FYI...I do have a Clymer manual.

Thoughts on what to check next and how to check it would be greatly appreciated. I can take pictures and post them of any part you wish to see more of. Thanks in advance for your feedback. I miss riding!!!

Spokes · « **Reply #1 on:** May 12, 2012, 05:39:09 PM »

I had a similar problem with my 550 yesterday. After searching everything, i realized I had disconnected a yellow wire beside the battery box that runs from the points to the coil. After I pushed the wires back together, I had spark. I don't know why the wire has a connector there, but was an easy fix once i found it.

cgswss · « **Reply #2 on:** May 12, 2012, 05:45:43 PM »

I think I'l try switching the wiring to the coils and see if the problem follows the coil. (Don't try to run it that way-just check the spark)

killersoundz · « **Reply #3 on:** May 12, 2012, 05:47:35 PM »

Probably a dead coil, 1 and 4 are on one coil, and 2 and 3 are on another.

GreenMachine · « **Reply #4 on:** May 12, 2012, 07:15:19 PM »

Thanks killer and cgswss for your replies. As mentioned, the resistance reading on the multimeter registers the needed ohlms on both sides of the coil (3 ohms). Could either side of the coil still be bad, despite a good meter reading? I would hate to buy a new Dyna coil (they are expensive!) if the coil I have is still good.

Thanks Spokes, I will double check the wiring again to see if any of the wires have been disconnected. That would be awesome if that in fact is the issue!

scottly · « **Reply #5 on:** May 12, 2012, 10:14:57 PM »

There have been numerous reports of failed Dyna ignition modules in the last couple of years. This would be the most likely suspect, before the coils, IMO.

luap · « **Reply #6 on:** May 12, 2012, 10:54:09 PM »

, did you run 2 12v wires to the dyna coils or pigtail them together , Bike isnt getting charge at 1100 rpm from some other threads the 3ohm coils need a reistor an I belive they take more juice all around. which at idle 1200 rpm your pulling off the battery, so you needing to hold the throttle at a light above 2500 rpm is charging the battery keeping the bike running,
I would put the stock coils back in an see if problem cant be solved.
check wires from ignition to coils- coils to 12v power
check battery volts see if bike is getting a charge,
an if you just buy new coils get the black dyna 5 ohm coils
just my 2 cents
paul

GreenMachine · « **Reply #7 on:** May 13, 2012, 11:44:17 AM »

Thanks everyone for your suggestions and comments thus far.

So, I checked all of the wiring again and all seems intact. I am receiving 12v power from the battery (it's a new battery). And I re-checked the coil resistance between the posts on both sides of the Dyna coil and I still get the required 3 ohms. I even disconnected the Dyna ignition module and checked for ac voltage on the red wire coming off the coil while the engine was cranking and I did get a low pulsing ac voltage.

So, I guess I am at a crossroads...either purchase a new coil (5 ohm Dyna to replace my 3 ohm Dyna, which most say is better anyway for this bike) and hope that fixes the issue or buy a new Dyna ignition to replace the old Dyna ignition (which could be faulty) and hope that fixes the issue or purchase both. $150 vs $300 essentially with no guarantee either or both will work.

Thoughts?

Rgconner · « **Reply #8 on:** May 13, 2012, 03:37:18 PM »

Swap the coils, see if the problem follows the coil.

then you will know what to buy and why.

TwoTired · « **Reply #9 on:** May 13, 2012, 03:44:50 PM »

Did you check the battery voltage? Even a new battery can become drained of power.

And the dynaS with 3 ohm coils draw 90 watts from a system with a 150 watt alternator.

cgswss · « **Reply #10 on:** May 13, 2012, 04:24:51 PM »

I'm sure you realize that one coil (right) controls 2 &3, the other 1&4. Right now your one coil is not firing. This could be the coil or it could be the wiring going to the coil. If you simply switch the wiring to the coils, we will have a better idea where to look. If you switch the wiring and the left coil continues to fire and the right dosn't, then its a good bet your wiring is OK and we can skip a lot of guessing.

We could also eliminate a lot of guessing if you made a jumper wire and connected the ground from the coil directly to the neg on the battery (this is just for testing- not a running mod.)

GreenMachine · « **Reply #11 on:** May 13, 2012, 06:26:36 PM »

Swapping the coil and/or switching the wiring is a great idea! If after doing that 1&4 don't work and 2&3 then work, then it has to be the one side of the coil that's bad. Genius! Will let you know what happens.

In terms of the battery, it does has a full charge (both the multimeter says it is fully charged and the trickle charger I put on it everytime that the bike is not in use says it is fully charged).

That 70s Bike · « **Reply #12 on:** May 13, 2012, 07:27:07 PM »

Quote from: GreenMachine on May 13, 2012, 06:26:36 PM

In terms of the battery, it does has a full charge (both the multimeter says it is fully charged and the trickle charger I put on it everytime that the bike is not in use says it is fully charged).

Keeping it on the trickle should mean it's fully charged.
For future reference, a discharging battery will read 12 volts right up to when it won't turn a starter, THEN, the voltage drops. That's why they're rated in AMP/HRS. Multimeter voltage does not indicate state of charge (until they're almost totally discharged) Bulb Hydrometer the specific gravity of the electrolyte is the old school way.

Rgconner · « **Reply #13 on:** May 13, 2012, 08:03:56 PM »

Well, sort of.

The resting voltage can tell you the state, at least with a lead acid battery:

http://www.buchanan1.net/lead_acid.shtml

The curve for li-ion and others can be a bit steeper. Li-ion will definitely have a sharp drop off.

GreenMachine · « **Reply #14 on:** May 14, 2012, 05:15:41 PM »

Well, I swapped the coils and yep its the right coil that is bad. After the swap, I got spark on 2 & 3, whereas before I didn't, and got no spark on 1 & 4 whereas before I did. It is so satisfying to finally now know what the problem is (determining the problem I have learned is 90% of the effort). Now all I have to do is swap out the old part for a new one and bang...Bob's your uncle (hopefully!!).

Thanks for the battery testing tips too!

Rgconner · « **Reply #15 on:** May 14, 2012, 06:53:43 PM »

Quote from: GreenMachine on May 14, 2012, 05:15:41 PM

Well, I swapped the coils and yep its the right coil that is bad. After the swap, I got spark on 2 & 3, whereas before I didn't, and got no spark on 1 & 4 whereas before I did. It is so satisfying to finally now know what the problem is (determining the problem I have learned is 90% of the effort). Now all I have to do is swap out the old part for a new one and bang...Bob's your uncle (hopefully!!).

Thanks for the battery testing tips too!

Glad to hear it!

Swapping parts like that is an important tool. I found a internally cracked spark plug that way once.

Swapped them, and instead of 1 farting once in a while, number 2 misfired like a machine gun. Swapping them made the crack worse I guess.

Just remember, change ONE THING at a time, at the smallest possible sub unit, or you won't know what resolved the problem.

GreenMachine · « **Reply #16 on:** May 17, 2012, 07:05:52 PM »

Well...the saga continues. Today I installed the new Dyna 5 ohm coil, believing that was going to correct my problem. Not so. I am still not getting spark on cylinders 2 & 3 (and the spark on 1& 4 is kind of weak IMO). However, through a series of swapping around different coil wire combinations (I literally this time tried every possible combination), I have without a doubt isolated the wire that is not working...it's the yellow wire coming off the coil that travels down to the grey Dyna ignition module wire. A cursory review of the yellow wire from coil to ignition does not appear to show any signs of being disconnected anywhere. What could be causing this specific wire to not be working properly? I checked fuses and they appear to be good. Could it be a faulty Dyna ignition module?? The previous owner had installed this ignition module approximately 18 months ago (so its relatively new).

GreenMachine · « **Reply #17 on:** May 24, 2012, 07:26:51 PM »

Since my last post, I was waiting for my new Dyna ignition module to arrive to replace my faulty Dyna ignition module (at least I think it was faulty). At last it arrived today (yahoo!). After a quick install and prior to fine tuning, I first checked to see if I was getting spark as I wanted to see if I was getting spark where I was not before (to validate if my prior module was indeed faulty). I checked cylinder 3 and got spark and I checked cylinder 4 and got spark (thereby essentially checking both sides of the ignition coil/module). Great!

Note: During the spark check process I noticed that the starter was not doing well and was struggling to facilitate turning the engine over (not sure why as my 2 month old battery was fully charged according to my charger).

Anyway, I then went to timing the ignition module and believe I got it timed fairly close to were it should be based on the installation instructions, the spark advancer markings, my timing light, etc. Accordingly, I tried to start the bike full on. I got the engine to start but only for a brief moment as the engine at constant throttle would rev well then putter down, rev well then putter down, rev well then full stop.

My thought was it was bad timing addjustments on my part so I want back to re-check my timing adjustments. After tweaking the timing a bit I attempted to again start the bike, this time the starter was barely helping to turn over the bike and as a result I was unable to crank her over to check my timing. Note: I checked my pipes out of curiosity and oddley 1 & 2 were still hot from my first attempt but 3 & 4 were cool (how is this even possible given they are on different sides of the coil/ignition?)

Anyway, after fussing a bit more, re-reading the Clymer manual, Dyna instructions, scratching my head, etc. I went back to try her again. All the while I was thinking...I just spent $300 for a new ignition coil and a new ignition module and neither of them have solved my problem. Anyway, I tried her again, this time no starter crank at all. Completely silent (dead). I tried to kick start the engine but could not get her to turn over that way either. No, I did not have my kill switch on.

At this point, I am done (at least until such time that I can rationally think again). In the meantime, any thoughts from the forum would be helpful as I am fresh out of ideas. I really thought for sure a new ignition coil and/or new ignition module would have done the trick (and maybe they did solve my problem and I just installed them wrong, or I did install correctly and now I have a new/different problem with the starter not working?). Most likely it's me being a very bad new mechanic!!

bollingball · « **Reply #18 on:** May 25, 2012, 05:36:12 AM »

Makes me like my simple little points and condenser that has allways served me well. Why not put it back like it was made. You know just for a test or did you put so much faith in that whiz bang Dyna stuff that you threw away the tried and true points set up? I know it is old technology but for just a few dollars you can switch a set of points and be back on the road. That is another thing I like about HondaMans setup you have a backup to switch to in less than 10 minutes and you are up and running. If I were in your situation every time I went on a trip away from home I would be thinking about that Dyna and all the post about there quality control lately.

Ken

GreenMachine · « **Reply #19 on:** May 25, 2012, 05:56:24 AM »

Thanks bollinball. When I purchased the bike last summer, the Dyna module was already installed (the previous owner disgarded the old system, not me).

MJL · « **Reply #20 on:** May 25, 2012, 08:55:10 AM »

If your spark plugs are fouled they can pass electricity without sparking, so I'd check those next.

Then, if it keeps fouling plugs, I'd be looking at the carbs.

GreenMachine · « **Reply #21 on:** May 25, 2012, 09:41:21 AM »

Thanks MJL. What aspect of the carbs would I look into to correct the cause of fouling plugs??

OneWheelDrive · « **Reply #22 on:** May 25, 2012, 11:00:28 AM »

I would clean, gap, and inspect the plugs, or get new ones altogether. Fouled plugs can caused fouled plugs :-) Sounds like the bike has been sitting for a bit. At this point you would be remiss not to remove and fully service the carbs. Pilot jets should be cleared with a wire (high E guitar string is perfect). Understanding how your carbs work, and knowing how to service them both on the bike and off is a crucial part in owning and enjoying these carbs. Have you downloaded the Honda service manual yet? The full 3000 mile tune up wouldn't be a bad idea.

Duke McDukiedook · « **Reply #23 on:** May 25, 2012, 01:48:44 PM »

the 3 ohm coils probably killed your kill switch like it did on my 750. Bypass it to make sure that is not the problem.
You may also have a loose or bad ground somewhere.

cgswss · « **Reply #24 on:** May 25, 2012, 02:02:17 PM »

From what I'm reading, you are having some sort of Battery problem and you need to figure that out first. Do you have any other 12v battery, like a car battery or something? I would love to see that bike on a different battery for testing so we know its getting full current. There is no way a new fully charged battery should run down so fast trying to crank the bike. Frankly to run down a battery that fast you would have to have somewhere that was very hot.

Next I would get out the vom and see if there is any shorts to ground indicated. I think I might un-plug the ignition module, fully charge the battery, and see if you still have problems with the starter. I don't think the ignition module could possibly pull so much juice as to effect the starter, but I guess its worth a simple test.

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Author Topic: No spark on Cylinders 2 & 3 (Read 8700 times)

bollingball