Absolutely mystifying failure, 850 Commando Mk III

johnm said:
I have a bit more time now so a longer explanation.

A friend's Yellow Peril replica. We were using rollers to start it so the engine was spinning up fine. No matter what we did only one side, always the same side, would run. Just like yours

The bike was wired exactly as per Pazon instructions. Sorry I don't know the exact Pazon unit but it wasn't the cheapest one nor the most expensive one.

Spark at both plugs when tested. But on a wasted spark system!!!! This is important.

Your message looks like a photocopy of what we did plus we're did a bit more as follows.

New plugs. BP7ES. Used 5 k resister plug caps. Wire cored HT leads
Swapped leads to other side
Went through the wiring with a multimeter testing every single connection. Giving them a good pull to check any break inside. I learnt the Boyer hidden broken wire in the trigger unit trick 10 years ago.
Disconnected the feed side to the ignition and just ran a wire straight from the battery to ignition bypassing all switches
Tested and swapped out coils. Standard coils with standard mounting.
Tested and swapped out leads and caps
Fitted new spare carbs. Checked fuel lines filters tank breathing etc. New gas.
Sent Pazon unit to Pazon for testing. We are in NZ so very easy.
Checked compression
Took rocker covers off and checked valve clearances and visual checked as close as able valve lift timing

Still nothing.

But then I talked further with my friend and realised that while he sent the black box to Pazon for testing he did NOT send the trigger plate.

Fitted a new trigger plate and checked rotor clearance.

Instantly started both cylinders.

We were fooled by the spark at both plugs. But we were seeing the wasted spark on the bad cylinder side.

And when we swapped the plugs over it made no difference because what had previously been the wasted spark on the non firing cylinder became the correct firing spark on the good cylinder. It also explained the occasional popping on the bad cylinder side. The wasted spark was firing the unused fuel in the cylinder and firing it out the exhaust.

You have checked and swapped pretty much everything as we did. But I bet one side of the trigger unit or associated rotor is your problem.

Just because you see a spark at a plug it doesn't mean it's there at the correct time. 😢😢😢😢

A couple of the other guys have also suggested this but I have detailed our tale of woe because it so closely matches your experience.
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YES! This is the most likely explanation and goes along with the troubleshooting guide that says a bad fit of the rotor could cause it. I would look carefully at the trigger plate and rotor clearance. My experience with the Altair albeit limited to one, has been excellent.
 
Nowhere does the OP say it's an Altair. Pazon makes the Sure-Fire, which is like the Boyer analog ignition; the Altair, digital ignition; and the Smart-Fire fancy digital ignition.
There are two different trigger methods for the digital ignitions. The older type rotor is a cylinder with 2 grooves 180 degrees apart. The present rotor has 2 wings instead of grooves. The PC boards are different so it's not upgradable and it was recommended to just buy a new unit. There were problems with the grooved type of rotor not being close enough with some cams.
I had the older rotor Altair in my bike and had no problems for years. But a weak kick would kick back and my knees were going. I went Tri-Spark.
(Source of info - not AI, just previous posts here and the Pazon site. Thanks marinatlas, blaisestation, and others for figuring this out a long time ago.)
Russ
 
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A huge amount of good info and I'm absorbing all of it.

Very busy with family and family-health issues, nothing real serious but it's keeping me out of the shop. I'm as anxious as everyone else is to finally find the culprit!!

Lannis
 
“Down to the short strokes” now, in this debugging process.



Summary – Right cylinder SUDDENLY quit running at cruise at 55 MPH, will only pop and backfire occasionally.



Compression – Valves are opening and closing normally, lifting the same amount on intake and exhaust on all cylinders. (So it’s not the camshaft). Compression pumps up normally to 175 PSI both cylinders (so it’s not a leaky valve). Valves take (by hand estimate) the same pressure to open and close them, so it’s not a broken valve spring.

Ignition – Both plugs spark “normally” on the head every engine revolution. Both plugs spark “normally” in place in the cylinder (per the clear spark detector plugged into the HV line). Swapped plug boots, plug wires, and coils; problem stays on right side (ie both coils will fire the left cylinder, neither will fire the right cylinder). The white "hot" wire from the ignition switch is supplying 12.5v.

Fuel – Swapped carbs; both carbs will run the left side, neither carb will run the right side. Fuel flowing freely through the ticklers on both carbs. Removed right side exhaust – clear all the way through, nothing has “fallen” to block the exhaust.

Removed the Pazon stator plate. The rotor is firmly on the taper. There are no obvious broken bits or traces on the stator plate. The trigger wires from the stator are two continuous wires from the setscrew connector on the stator plate all the way into the Pazon black box, no connectors. The wires had been installed with due allowance for movement between the isolastic-mounted engine and frame – loops, loose clamps, no binding points, no pull points. Stripped the plastic sheathing off the wires (YB and WB) and felt/bent them all the way into the black box – no broken conductors.

So I’m about stuck with replacing parts. It’s not mechanical or fuel; it has to be the electronic ignition, I believe. I have no way of testing the Black Box to see whether it has lost its little electronic mind or not, or if the coils on the stator plate are behaving as they should.

1) Put the points and auto-advance and condensors and ballast resistor back in? I’d have to re-learn how it all went into place. I didn’t cut any wires on the way out.

2) Buy a new Pazon and put it in place? That’s the easiest thing to do.

3) Buy a Tri-Spark or a Boyer and put it in place?

I just can’t see what else it can be.

Lannis
 
As everything seems to work when kicking over maybe its vibration related that only shows once the engine is running. A loose connection or an internal break in a wire that makes contact until the engine starts and then either disconnects or randomly connects. The worst type of fault to find.
 
kommando said:
As everything seems to work when kicking over maybe its vibration related that only shows once the engine is running. A loose connection or an internal break in a wire that makes contact until the engine starts and then either disconnects or randomly connects. The worst type of fault to find.
Click to expand...
Possibly, but the right cylinder never fires even once normally when the button is pushed. The left side fires instantly and regularly, the left never anything but an occasional pop or backfire .....

Lannis
 
So using the HT inline tester are you seeing sparks on the right when its not igniting under the starter and then also when the left is firing and the engine running ?. Possibly if you are you are only seeing the spark on the low compression stroke and not the high compression power stroke making you think the right is sparking every 180 when its every 360 and not the spark you need for the right to fire on the power stroke. I wonder if a colortune would show more about the spark.
 
kommando said:
So using the HT inline tester are you seeing sparks on the right when its not igniting under the starter and then also when the left is firing and the engine running ?. Possibly if you are you are only seeing the spark on the low compression stroke and not the high compression power stroke making you think the right is sparking every 180 when its every 360 and not the spark you need for the right to fire on the power stroke. I wonder if a colortune would show more about the spark.
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That's the conclusion that I'm coming to.

And since if that's the case, the Pazon is just broken, I'm thinking it's time to just replace the ignition and not speculate on failure modes.

I have been guilty in the past of wasting money to replace a part that was not bad because I had not done my due diligence, but ...

A Boyer has been running my BSA for 18 years and tens of thousands of miles with not a hiccup, so I'm tending toward one of those if I don't put the points back in.

Lannis
 
Try this, take the left side HT lead and pull it off the sparkplug and tie it out the way enough so a spark cannot jump the gap. Then see if the right side will fire at all.
 
That doesn't cost anything. I'll try it when I'm out in the shop later and report back. Thanks!

Lannis
 
Lannis said:
That's the conclusion that I'm coming to.

And since if that's the case, the Pazon is just broken, I'm thinking it's time to just replace the ignition and not speculate on failure modes.

I have been guilty in the past of wasting money to replace a part that was not bad because I had not done my due diligence, but ...

A Boyer has been running my BSA for 18 years and tens of thousands of miles with not a hiccup, so I'm tending toward one of those if I don't put the points back in.

Lannis
Click to expand...

Hey Lannis, I purchased a brand new spare Pazon Altair when I was troubleshooting my kickback issues. So I keep a spare, just the same as I did with a spare Boyer. You're welcome to it if it'll help you.
 
concours said:
Hey Lannis, I purchased a brand new spare Pazon Altair when I was troubleshooting my kickback issues. So I keep a spare, just the same as I did with a spare Boyer. You're welcome to it if it'll help you.
Click to expand...
Thank you! DM sent.
 
If you have them, put the points/AAU back in! :) If not, I agree with the TriSpark recommendation. I removed a Boyer from my poorly-running Commando shortly after buying the bike (2006) and installed the points/AAU. It ran great and I had no intention of ever installing an EI. But I became aware of the Trispark a couple of years later and was interested primarily because unlike the Boyer, the Trispark duplicated the factory ignition curve. So I purchased/installed the Trispark which has been totally reliable for 15+ years.

FWIW - couple of years ago I removed the TS and put the points/AAU back in out of curiosity regarding electrical power necessary to operate the point system vs the TS. Surprisingly to me, the battery charging voltage was slightly higher (good!) with the TS than with the points!

Another FWIW - if the EI does NOT match the OEM ignition curve, you will lose some midrange power compared to the points/AAU or an EI that matches the factory curve which is full advance by around 2800-3000 RPM.
 

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