pop, fart, sneeze....

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o0norton0o

o0norton0o

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Well, something has gone haywire. All of a sudden my plugs are really rich and the bike is running erratically. popping out the exhaust and wont stay running.... I inspected my ignition system today. I have a boyer microdigital. I looked at the timing pickup wires, and they seem soundly connected to their coils to me. I looked for skinned wires and found nothing wrong and all my connections look good.

I have an old black box boyer with the pick up and magnet that I can swap out for the red box microdigital to test the IE. I think the thing that bothers me to most is that I have to take the gas tank off to swap the IE box... I really need to mount the damn box in more accessable place.

My guess is either my boyer is screwing up or my coil is cutting out. Since I don't have an extra dual lead coil, it would be a royal pain in the ass to remount my lucas coils to swap out my dyna coil to check it... It was measuring 3.7 ohms and tested at over 12 volts but I still think it could be heating up and cutting out.

I also have a carb body that is sticking slightly and I have to tap the carb with something to make it drop when it sticks... I'm thinking about taking some valve grinding paste and honing the parts until they slide easier (the inner carb body is sleeved and the outer is bored

... I've been getting some great rides lately. This came out of the blue. I guess I am lucky that I made it home from my last ride... Any intelligent suggestions or comments are appreciated.. thanks
 
o0norton0o said:
Well, something has gone haywire. All of a sudden my plugs are really rich and the bike is running erratically. popping out the exhaust and wont stay running.... I inspected my ignition system today. I have a boyer microdigital. I looked at the timing pickup wires, and they seem soundly connected to their coils to me. I looked for skinned wires and found nothing wrong and all my connections look good.

I have an old black box boyer with the pick up and magnet that I can swap out for the red box microdigital to test the IE. I think the thing that bothers me to most is that I have to take the gas tank off to swap the IE box... I really need to mount the damn box in more accessable place.

My guess is either my boyer is screwing up or my coil is cutting out. Since I don't have an extra dual lead coil, it would be a royal pain in the ass to remount my lucas coils to swap out my dyna coil to check it... It was measuring 3.7 ohms and tested at over 12 volts but I still think it could be heating up and cutting out.

I also have a carb body that is sticking slightly and I have to tap the carb with something to make it drop when it sticks... I'm thinking about taking some valve grinding paste and honing the parts until they slide easier (the inner carb body is sleeved and the outer is bored

... I've been getting some great rides lately. This came out of the blue. I guess I am lucky that I made it home from my last ride... Any intelligent suggestions or comments are appreciated.. thanks
Click to expand...

Well the symptoms sound like fouled plugs. Before I pulled the tank I would put a new set of plugs in it to see if it runs better. If it does then you will need to do some carb tuning so they don't foul again. Jim
 
Checked your battery voltage ?
Some of those leccy ignitions don't like low voltages, so if your battery is low or not up to snuff,
always worth checking...

Plugs are always No 1 thing to change 1st though.
 
yeah, the plugs were fouled and I cleaned them off. reinstalled them and they fouled again. The bike was missing then popping out the exhaust on the next stroke. I ended up put a pair of BPR6ES (hotter plugs) in the bike and it still missed, popped and farted...

I tested the voltage and it was 12.38. I am sure I have a few sets of plugs around here., if not I'll buy another pair.

Both plugs were fouled black and full of soot.
 
Fouled plugs can certainly be caused by ignition problems but, check simple things first, like are the enrichener slides pulled up. Maybe check for a broken enrichener cable.

Broken boyer pickup wires are a distinct possibility. Jim
 
The Micro Digital needs to run with suppressed plugs or caps (just one or other not both). Before you get into taking it all apart check you have these and also strode the ignition timing to be sure it has not slipped as Fast Eddie's did.
 
Thanks,... I'll give everything mentioned a look. I hate going backwards, but I guess it's my turn...

I have the k&n air cleaner off so I can inspect the slides. One slide is sticking open occasionally. Any ideas on loosening it up? maybe use some valve lapping paste and work the inner body back and forth to hone them against each other to loosen them up ??
 
o0norton0o said:
Thanks,... I'll give everything mentioned a look. I hate going backwards, but I guess it's my turn...

I have the k&n air cleaner off so I can inspect the slides. One slide is sticking open occasionally. Any ideas on loosening it up? maybe use some valve lapping paste and work the inner body back and forth to hone them against each other to loosen them up ??
Click to expand...

Loosen the two top cover screws. If they are tightened too much the slide will stick.
Same with the carb mounting nuts.
Just snug with blue locktite is the way to go. Jim
 
All the above in combo can do this but sounds like low voltage maybe intermitently along the supply path, key, battery, fuse, bar kill, all terminals plus breaks under insulation. A distance short may be lowering voltage in stactato cuts but not blowing fuse. Slide air leak wear aggravate its sticking and may be leaning that side to cough. Gremlin bells are nil protection from evil shoe eves.
 
well, I poked all the idle circuit openings out gentley with a guitar string. I pulled the center carb bodies out and the needles were displaced. I got the bike running, but I think the plugs need a good cleaning. I'm going to put fresh one's in but for now I need to see if I am back to normal... Thanks for all the help... I may have more issues. I won't be sure I found my issue until I ride around a bit...

The original running rich could have been one of the carb body sticking in the up position... I could have displaced the needles by checking them with a finger to see if they were moving with the carb body once my issue began and I started to check things. Perhaps it was one stuck carb body all along that I thought was an electrical miss.

For a while it ran on one side normal and the other side didn't run right. The exhaust pipe was only warm while the other was hot..

thanks again...
 
well, cleaning out the idle circuit helped the idle. It's idling pretty nicely,...... but when I lift the throttle to about 3,000 rpms, it sporadically misses and pops in the timing side's exhaust pipe.

Because a boyer microdigital uses lost spark, and the coil is a dual lead single coil, I don't see how it could be an ignition issue. The only thing that is specific to either the left or right cylinders is the plug and the plug wire. I put new plugs in the bike. I supose I should try switching the plug wires to see if the miss moves to the other side...

I am more thinking that maybe the needle clip is weak the needle jumped out of the clip because of the RPM range that I am getting my pops and misses from. My other idea is that maybe the float is punctured or something like that (even though it's a new float I think)

It seems to me that it's most likely a carb issue because it's only missing on one side...

When I had the plugs out, I rotated the kick start and put my thumb over the plug hole and there was pressure, so I know the valves are closing.

Am I missing something obvious?

Thanks again.... and again...
 
o0norton0o said:
well, cleaning out the idle circuit helped the idle. It's idling pretty nicely,...... but when I lift the throttle to about 3,000 rpms, it sporadically misses and pops in the timing side's exhaust pipe.

Because a boyer microdigital uses lost spark, and the coil is a dual lead single coil, I don't see how it could be an ignition issue. The only thing that is specific to either the left or right cylinders is the plug and the plug wire. I put new plugs in the bike. I supose I should try switching the plug wires to see if the miss moves to the other side...

I am more thinking that maybe the needle clip is weak the needle jumped out of the clip because of the RPM range that I am getting my pops and misses from. My other idea is that maybe the float is punctured or something like that (even though it's a new float I think)

It seems to me that it's most likely a carb issue because it's only missing on one side...

When I had the plugs out, I rotated the kick start and put my thumb over the plug hole and there was pressure, so I know the valves are closing.

Am I missing something obvious?

Thanks again.... and again...
Click to expand...

Make sure the jet holder has not unscrewed from the bottom of the carb. Inside the bowl. Jim
 
If common Commando issues were always obvious this forum would be pretty slow. You obvious have a repeating carb/slide/needle hang up - assumed on side of misfire - so nothing for it but repeat electrical exams while awaiting new anodized slide or cable or cable junction or new clip and needle or new carb(s). The more I post here the more I can put off facing another full assembly with its risk of screwing up or missing something to make me wish I only had moderns but found out they get similar lets downs if used regularly or stored long. Basic mc hobby is real cause of course.
 
comnoz said:
Make sure the jet holder has not unscrewed from the bottom of the carb. Inside the bowl. Jim
Click to expand...

I figured I have to look there next and recheck to make sure the needle and clip aren't misaligned again.... I actually hope that the needle jet has come loose because that's easily remedied...

The other day I almost posted on a thread that amal carbs are easy to adjust once you figure out how they work, and now I am going through the multiple assembly/diassembly headaches that I thought I was well beyond...
 
Double trouble... would make sure there is not an issue with the Boyer as well as the carbs. The lead from the pick ups should not be pulled taut by engine movements,
check your battery voltage a dead cell will give you these problems, as will a broken wire to the pickup coils , has the lead from the pickups chafed leaving a bare wire
intermittently shorting out to ground , a loose connection on the circuit ? Do use a proper crimping tool on connectors . These are all problems I have had with Boyer.
I bought one of the very first units Gus Khuns had in stock-this backin 1972. It gave over 20years service and was much more robust than some of the later kits.
 
It did not go well. One cylinder seems strong, the other not so much... perhaps I screwed the pooch... I'm still getting pops and farts out of the side that seems weak to me. I guess I am going to check compression now..

Update: I got about 130 psi on each side. They were very close to being exactly the same. I don't think that 130 is great compression but it wouldn't explain a miss on one side.

I have an old black box boyer that I can substitute for my red box microdigital.

I guess I will try to add a ground directly from my coil and my red box to ground.

Then try substituting my extra boyer parts one at a time.

then I'm going try the coil wires, then coil substitution... (which I don't have an extra one of...)

*I wonder if a dual coil could have one bad lead??
 
Before changing rest of Boyer system once you have checked it all looks good then first swap the plugs an leads to the opposite sides. If this makes the problem swap sides then its those parts that are suspect and it should be less work than changing other Boyer components.
 
Well,....... the coil wire leads were just barely able to reach the plugs on the opposite sides, so I switched them as a test. The mid range miss didn't change sides, so I am assuming that the missfire can't be ignition related since the miss is clearly on one side and in the mid range RPM's only. The plugs are brand new. The battery measures 12.5 volts with the lights on...

So, here's where I am at:

When I disassemble the carb inner bodies, the side with the misfire slides in and out of the carb body easily. the other side is tight. I am thinking that maybe one carb wore faster than the other and I am experiencing a lean condition at midrange because of excessive carb body wear on one side. Both carbs are sleeved btw.

I don't see myself swapping carbs from one side to the other to check to see if the missfire changes sides with the swap, because the bleeders and adjustment screws would be on the wrong sides. I am going to check for air leaks on the manifold first, and then I am thinking about moving the carb needle up one notch on the missfire side to see if it eliminates the missfire.... If it does eliminate the missfire, could this be a workable solution or is it a temporary bodge?

thoughts and opinions, ??? thanks in advance for all the help...
 
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