Author Topic: Could it be my Dyna III Acting up?  (Read 2782 times)

Online bigbikerrick

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Could it be my Dyna III Acting up?
« on: May 13, 2017, 02:16:50 PM »
Hello Folks, this is on my 85 Le Mans, after riding it for about 20 minutes, Intermittently,the idle will become very rough, sometimes the engine dies. I have checked timing, valve clearances, plugs look fine, I have newer ngk caps and wires, carbs are fine, recent synch checked, and spot on. Yesterday when it did it, i realized it sounded like it was running on only one cylinder, so I reached down , and pulled the left plug cap, it had no effect on the running, after getting the cap close to the plug a few times, it started firing, and ran perfect after that. It seems to me the left cylinder drops out intermittently , but only at idle. I have some yellow/orange colored coils that look like the dyna coils in shape. I am not sure what brand.
Any suggestions where to start diagnosing the culprit here?
Thanks alot!
Rick.
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Offline Doug McLaren

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Re: Could it be my Dyna III Acting up?
« Reply #1 on: May 13, 2017, 02:26:12 PM »
Sounds suspiciously like a coil breaking down as it heats up. I've had a couple of Dynas on my old 850's, the bullet connectors were a bit of a pain, seemed to be of poor quality and prone to failure. In fact the only time my Le-Mans broke down in 16 years of ownership was when a Dyna coil failed followed closely by the black box, luckily I was only a couple of hundred yards from home on my way back from work so it wasn't a long push.
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Offline guzzisteve

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Re: Could it be my Dyna III Acting up?
« Reply #2 on: May 13, 2017, 02:37:20 PM »
You could use a timing light on it to see if it is spark failing.
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Re: Could it be my Dyna III Acting up?
« Reply #3 on: May 13, 2017, 03:35:58 PM »
What cylinder?  Right?  If right you could be losing the box.  Check coils with a magnifying glass for cracks.  You could retrofit back to points.
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Re: Could it be my Dyna III Acting up?
« Reply #4 on: May 13, 2017, 04:22:16 PM »
Thanks guys for the tips, Thats a good idea, Steve, to use the inductive timing light . I took the bike for a 1 hour ride today, in 90 degree heat, and ran fine, didnt do the idle thing. I hate intermittent problems!  Its the left cylinder that drops out, not the right.
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #5 on: May 13, 2017, 04:42:51 PM »
Under the dist. cap there are two little rectangular boxes (sensors?) that contact the rotors. I've had one of those crap out on me. Dyna actually sent me one for free. I have had a coil ooze black shyte for the posts one time. Other than that, only problems in 28 yrs. of Dyna ownership.


I also had a long time Dyna user tell me to clean the underside of the board in the dist. but I've never done that.

Just my 'sperience <shrug>
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Offline DonTom

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Re: Could it be my Dyna III Acting up?
« Reply #6 on: May 13, 2017, 05:08:33 PM »
Hello Folks, this is on my 85 Le Mans, after riding it for about 20 minutes, Intermittently,the idle will become very rough, sometimes the engine dies. I have checked timing, valve clearances, plugs look fine, I have newer ngk caps and wires, carbs are fine, recent synch checked, and spot on. Yesterday when it did it, i realized it sounded like it was running on only one cylinder, so I reached down , and pulled the left plug cap, it had no effect on the running, after getting the cap close to the plug a few times, it started firing, and ran perfect after that. It seems to me the left cylinder drops out intermittently , but only at idle. I have some yellow/orange colored coils that look like the dyna coils in shape. I am not sure what brand.
Any suggestions where to start diagnosing the culprit here?
Thanks alot!
Rick.
This info. might not be related to your MG  problem, but I had a very confusing but very simple problem on my Dyna Three on my 1971 BMW. The main symptom was that the engine would die going downhill, even with using throttle, but had full power when going up hill, then no trace of an issue. Uphill was never a problem. And it would occasionally miss a few beats  on level ground, perhaps one time in fifty miles for a few seconds or so.

The problem was  loose mounting screws on the plate for the Dyna pickup coil. The pick up coil plate has NO ground wire but needs a ground to function. It relies on the plate being grounded to the engine by the plate screws. When down hill, gravity made the plate lose the connection to ground. The plate and what it grounds to must be clean and have the screws tight. I do not know if this has anything to do with how the Dyna Three works on your bike, but if there is a pickup coil plate, make real sure it has a good ground.

-Don-  Reno, NV
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Online bigbikerrick

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Re: Could it be my Dyna III Acting up?
« Reply #7 on: May 14, 2017, 12:08:57 AM »
Thank you, Don, and John for the suggestions. You guys may just be on to something here. I remember reading somewhere that the bottom of the dyna plate has to be very clean to make good contact with the distributor body. My bike does occasionally " miss a beat"  or stumble when running, but mostly at idle. I will check the plate, and mounting screws for snugness as well.
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #8 on: May 14, 2017, 09:01:45 AM »
Connect the timing light to the bike and you can see if the spark is consistently firing or misfiring.  Watch the light pulse and listen to the motor.  Or put an inline sparkplug tester light on the bike and go for a ride after dark. 

Offline Goosecoop

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Re: Could it be my Dyna III Acting up?
« Reply #9 on: May 14, 2017, 11:37:01 AM »
And to add to the possible causes, I chased a similar problem for 2 years and finally called Dyna. I was told by a technician to remove the plate that is in the distributor, turn it over and with a bright light and magnifying glass check the solder joints. If any of the joints have a small gap take a pencil soldering iron and touch it to solder the joint again. I did that, found the soldered joint that was not soldered very well. I touched all the soldered joints just to make sure and haven't had a problem since.
Mike
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Re: Could it be my Dyna III Acting up?
« Reply #10 on: May 14, 2017, 01:52:43 PM »
Thank you, Mike, and OG, Thats some good advice!
 I will check those things today. I want to take it for a ride first, with the timing light in my tank bag ready to hook up if and when it acts up.
I took it out yesterday evening, and except for a couple of "missed beats" it behaved normally, and ran very strong.
Rick.
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Offline MikeW

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Re: Could it be my Dyna III Acting up?
« Reply #11 on: May 14, 2017, 08:00:16 PM »
I've been through several issues with the Dyna III I fitted to my Le Mans 1000.

I had a coil failure and latter on, a module failure. Both started off with poor idle and then missing at low rpm on takeoff. Finally it failed totally on one side during a ride (but worked again the next day which confused the hell out of me..) You can swap the coils and even the module wires to determine whether it's a pickup, module or coil problem using an induction timing light.

I sent mine back to Dyna for testing and they sent a replacement module back a week latter (the pickups were fine). I found their customer service pretty good.

Obviously you should also check your wiring for dodgy connectors and wiring before pointing fingers because these are old bikes!

Mike
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Re: Could it be my Dyna III Acting up?
« Reply #12 on: May 14, 2017, 10:41:59 PM »
I was having pretty much the same symptoms  my SP. Misfires happened on both sides, which made it hard to isolate which cylinder was at fault.  Poor idle , hesitation, engine stalling after warming up.  In any case, off came the Dyna and, after futzing around setting up the points plate and resetting the timing with a timing light, the bike went back to running normally. Still thinking about sending the Dyna  stuff back to the manufacturer for testing, but perhaps the points are staying on the bike.
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Re: Could it be my Dyna III Acting up?
« Reply #13 on: May 15, 2017, 12:27:07 PM »
Mike W, thanks for the reply, that sounds like exactly like what mine is doing, except its intermittent, so it will perform fine for a couple of days, running like a raped ape,well up past 100 mph without a hiccup, then one day it will crap out at idle for a few minutes, but by the time I try to diagnose it, it clears up! I hate intermittent problems that may leave me on the side of the road, since I ride on some desolate desert backroads in Arizona, where frequently there is no cell service. I checked the plate bottom for any broken solder joints, or cracks, and found nothing abnormal.
Does dyna test the components for free ,if I ship them the whole thing?
I have a Dyna II also in my Cal II automatic, but that beast is running perfect, so I hate to mess with it to swap out components, since it was such a PITA to get the timing perfect for both cylinders, but that may be my other option.
Thanks again, Sir!
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #14 on: May 15, 2017, 12:36:52 PM »
I was having pretty much the same symptoms  my SP. Misfires happened on both sides, which made it hard to isolate which cylinder was at fault.  Poor idle , hesitation, engine stalling after warming up.  In any case, off came the Dyna and, after futzing around setting up the points plate and resetting the timing with a timing light, the bike went back to running normally. Still thinking about sending the Dyna  stuff back to the manufacturer for testing, but perhaps the points are staying on the bike.

Thanks, Guzzista! I would really hate to go to points,on my Le Mans. I dont mind the single points on my eldorado, they are pretty painless to work with, but my experience with the dual point dist. on my Cal II , before I went to  the Dyna, was not fun...very cramped space to work in, and fidgety to get both set right. Oh well, at least the Dynas are not too expensive...I wish we had more options out there that dont cost a fortune.
Rick.
« Last Edit: May 15, 2017, 12:38:03 PM by bigbikerrick »
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Offline MikeW

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Re: Could it be my Dyna III Acting up?
« Reply #15 on: May 15, 2017, 05:49:27 PM »
Mine was replaced under warranty so I can't say if there's a charge for older systems.

If you do want to send it back for testing you will need to contact Dyna for a return number.

Coils can have an effect on the module's lifespan too. Dyna no longer recommend 3 ohm coils in their supplied instructions. You can check your coils with an ohm meter by measuring across the primary winding.

Mike
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Re: Could it be my Dyna III Acting up?
« Reply #16 on: May 15, 2017, 08:00:53 PM »
I have two other Guzzis with Dynas that work like a charm ( one still runs original Marelli Coils!) . One of these days I will bolt up the 5 OHM Dyna Coils. There is no doubt that high RPM advance is better with electronics. As the left point plate has to be modified to get correct retard,( See this and thanks Greg Field)) http://www.thisoldtractor.com/moto_guzzi_tonti_distributor_dual_points_plate_modification_so_you_can_time_both_cylinders_properly.html   and ,not much room to work without removing the tank, a Dyna or similar becomes more and more attractive.  Nice that Dynatek will test their equipment for free.
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Re: Could it be my Dyna III Acting up?
« Reply #17 on: May 24, 2017, 05:46:13 PM »
Hey Guys, I wanted to let you all know, I found the problem with my Le Mans today! the 2 screws holding down the dyna 3 plate to the distributor, did not have threads all the way to the heads, and although they were "tightened" down , the plate was still a bit loose, and apparently was only getting grounded intermittently. I noticed it when I was attempting to measure the gaps between the pickups and  the rotor, I noticed the plate/pickup would slide sideways, and the gap would change, or be non-existent. I placed a couple of tiny washers under the screws, tightened down with a drop of loc tite, and the plate is solid against the distributor. I took it out for a  short test run, and it ran perfect, without a hiccup, and great torque.
Thanks alot to all that helped me.
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #18 on: May 24, 2017, 06:14:32 PM »
Great followup, thanks.   Always good to know how the story ends ....

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Re: Could it be my Dyna III Acting up?
« Reply #19 on: May 24, 2017, 06:57:40 PM »
Yep, I'll take all the Dyna 'sperience I can get since I have two. Thanks for the report!
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Re: Could it be my Dyna III Acting up?
« Reply #20 on: May 24, 2017, 08:09:16 PM »
I'm glad you found the plate/screw issue.  BTW, I don't recall if you have mentioned what coils you have or if still running the originals.

For general information, I had a very similar situation on my SPII.  In particular it would drop one cylinder just as you started out off of idle at a traffic light.  Easy way to get rear ended!  I chased the problem for a year.  Thought it was carbs, fuel flow, plugs, wires, etc.  Eventually, it failed completely on one cylinder and that made the diagnostics easier.  I found out through use of an inductive timing light.  I would remove a plug and watch it spark. Then reinstall and couldn't get that cylinder to fire.  Must be fuel.  Nope.  Eventually, I clamped a spare plug to the cylinder head guard and moved the secondary wire and cap to that outside plug.  Using an inductive light I could see that the outside plug was firing.  Then moved the wire and cap to the installed plug.  No fire.  WTF???  Swapped the plugs in and out and got the same results.  Determined that the coil would fire the plug in open air but not in the compressed atmosphere of the cylinder.  Learned from the Internet that it takes much more amperage to fire in a compressed atmosphere.  Installed new coils and the rest is history.

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Re: Could it be my Dyna III Acting up?
« Reply #21 on: May 24, 2017, 11:53:47 PM »
 Hi Patrick, I am running some orange ish colored , aftermarket coils that came on the bike . I am not sure what brand they are, but they test out at 4.8 ohms . They are shaped like the dyna coils. I should probably replace them with  new dyna coils , just to rule out any possible  future issues. On my California II , I also have a dyna III, and am still running the stock Marelli coils from 1985, and its been faultless .
Thanks,
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #22 on: May 25, 2017, 09:51:04 AM »
I know you have some rough idle issues.  Does the bike seem to stumble in particular in the first 20 yards as you pull off of a red light?  I think a borderline spark gets overly challenged by the suddenly slightly richer mixture as you open the throttle.  Try the experiment I did.  Clamp a spare spark plug against the head somewhere within reach of the secondary cable.  Use an inductive timing light to watch and verify the spark pulses.  Put the secondary wire onto the outside mounted plug and run the bike on one cylinder while you watch the strobe for the other.  Now move the secondary wire to the installed spark plug and repeat.  Are the spark impulses even and equal?  Repeat for the other cylinder on the other side.  You might detect something erratic in the idle speed firing.

I replaced my weakened stock coils with Dyna and now all is good.

Patrick Hayes
Fremont CA

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Re: Could it be my Dyna III Acting up?
« Reply #23 on: May 25, 2017, 09:58:06 AM »
For a data point.
I have green coils that are for dual plug heads. The measure 3.5 ohms hot or cold. Since I have heard so many tales of woe for the 3 ohomers I have always assumed they were the bad apple when the ign started acting up. Not! (always minor corrosion being the problem now solved.)
I have had a couple of long conversations with the Dyna folks and they tell me not to worry about the 3 ohmers so I don't any more  (but is always a check if problems arise.) and since I sport no electronics on the machine I used copper ign wires!

Good that you got it sorted!

:-)

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Re: Could it be my Dyna III Acting up?
« Reply #24 on: May 25, 2017, 02:52:03 PM »
Thats an interesting experiment, Patrick! a great idea to rule out a failing coil. I am going to rig that up....I love stuff like that! I have also notice quite a bit of "wear" on the bottom outer edge of the Dyna III plate where it was vibrating around on top of the distributor body due to the play created by the screws not having long enough threads to tighten down snugly. I removed the screws from another tonti distributor I have and they are the correct ones. I also need to check the timing for both cylinders to make sure its correct after all the fiddling around i have been doing.
Thank you, Guys for all the great suggestions!
Rick.
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Re: Could it be my Dyna III Acting up?
« Reply #25 on: June 01, 2017, 12:56:27 PM »
Hey Folks, I just wanted to update you all on my new findings. I took the Le Mans out for a ride yesterday, all had been well after properly tightening down the sensor plate, on the last two times I rode it, well lo and behold....yesterday, it "crapped out "again, started idling bad, hesitation on takeoff, then all fine at higher rpms.Exactly like what Patrick Hayes describes in his above post. I isolated it to the left cylinder  as the cause. I went home, swapped the wires from the coils from left to right, and took the bike out for a test ride, same problem after warm up, but now on right side, so I am 99% sure its my coil gone bad. the suspect coil tested out to 3.8 ohms, and it does have the brown "epoxy" dripping down the metal mount post.
A new pair of black dyna coils should arrive  tomorrow, I will let you know if that solves my problems....fingers crossed ! :laugh: :laugh:
Thanks.
Rick
« Last Edit: June 01, 2017, 12:59:56 PM by bigbikerrick »
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