74 Commando Boyer Testing

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Dumped a bit of gas in the cylinders, wrenched the plugs in, kicked it over a few times and the kickstarter sprung back and just about broke my foot. Is that normal? I'm still sitting here wondering if my foot is broken.
 
Kick back can happen with excessive advance timing. Have you confirmed your timing scale on the primary cover is accurate (timing disk on rotor and piston stop method)? Mine was out 1.5 degrees. My boyer-clone Wassel EI likes around 28deg BTDC. If I push it to nearer 31, iget bitten by kick back.
 
I wouldn't say it was entirely normal but it can happen if the ignition is overadvanced as mentioned or you didn't kick correctly.

Even when the accuracy of the timing scale has been checked the actual ignition timing can only be accurately checked with a strobe.
 
When I spin the motor over and find TDC are there two strokes? As in...is there a TDC during intake stroke and another at exhaust?
 
MarkDeaton said:
When I spin the motor over and find TDC are there two strokes? As in...is there a TDC during intake stroke and another at exhaust?
Click to expand...

It's a 360 degree, 4-stroke vertical (parallel) twin so as the pistons approach TDC, one cylinder will be on its compression stroke and the other will be on the exhaust stroke.
After one crankshaft revolution, the other cylinder will then be on the compression stroke and the first will be on the exhaust stroke so there's one 'compression' for each revolution of the crankshaft, if that's what you mean?
 
L.A.B. said:
It's a 360 degree, 4-stroke vertical (parallel) twin so as the pistons approach TDC, one cylinder will be on its compression stroke and the other will be on the exhaust stroke.
After one crankshaft revolution, the other cylinder will then be on the compression stroke and the first will be on the exhaust stroke so there's one 'compression' for each revolution of the crankshaft, if that's what you mean?
Click to expand...
Just wondering for timing purposes if it matters.
 
MarkDeaton said:
Just wondering for timing purposes if it matters.
Click to expand...

No, as the Boyer is a 'wasted spark' ignition system so the plugs spark simultaneously every 360 degrees.
The spark on the exhaust stroke cylinder being 'wasted' each time so static ignition timing can be done with either cylinder on the compression stroke.
 
L.A.B. said:
No, as the Boyer is a 'wasted spark' ignition system so the plugs spark simultaneously every 360 degrees.
The spark on the exhaust stroke cylinder being 'wasted' each time so static ignition timing can be done with either cylinder on the compression stroke.
Click to expand...
Thanks sir. I backed off the timing to around 28 and it's not waking up. Seems pretty picky so will try maybe closer to 30. 31 kicked me like a mule so I am a bit shell shocked. Foot still hurts a day later.
 
Clear the clutch, tickle the carbs, ignition on, no throttle now, commence the kick, after ensuring that, initially and gently, you have made the k/s pawl engage with the layshaft gear the pawl lives in, then with all the bodyweight you can muster on your right leg let your Norton know that failing to start is not a choice. Near the bottom of the kick open the throttle quickly; this should produce the desired results.

If your static timing is set to anywhere near 28 to 31 degrees you will injure some body part or joint. I'd suggest that you keep backing the timing down. I believe that this has been mentioned earlier in this post, but the black box Boyers are sensitive to voltage. The Boyer MicroDigital and the TriSpark, the two brands I'm familiar with, are much less sensitive.

One last thought. If someone in the bike's history wired, or miss wired, the ignition switch and/or the toggle switch in the headlight such that the headlight and tail light come on with the ignition circuit, that situation will draw off considerable voltage.

Best.
 
RoadScholar said:
If your static timing is set to anywhere near 28 to 31 degrees you will injure some body part or joint.
Click to expand...

Static timing is set at full advance. When kickstarting the ignition is (or should be) fully retarded.

RoadScholar said:
believe that this has been mentioned earlier in this post, but the black box Boyers are sensitive to voltage.
Click to expand...

Boyer "black box" Micro MkIII is, Micro MkIV isn't (although this could well be a MkIII box).
 
The MKIV is not as voltage sensitive as the earlier MK3 was - it will operate at under 10 volts now.

If it's kicking back like that, two things to check:

1) are you timing it 180 degrees out, on the opposite alternator mark?
2) are your black/white and black/yellow wires between the ignition stator and the black box the right way round - connecting them up the wrong way doesn't necessarily stop the bike from running, but it does stop the advance/retard from working correctly - which can result in bad kickback.

I feel your pain - there is nothing worse than a bike that kicks back like that - you lose confidence in it, and don't want to go near it any more (at least that's how I feel)
 
RoadScholar said:
Clear the clutch, tickle the carbs, ignition on, no throttle now, commence the kick, after ensuring that, initially and gently, you have made the k/s pawl engage with the layshaft gear the pawl lives in, then with all the bodyweight you can muster on your right leg let your Norton know that failing to start is not a choice. Near the bottom of the kick open the throttle quickly; this should produce the desired results.

If your static timing is set to anywhere near 28 to 31 degrees you will injure some body part or joint. I'd suggest that you keep backing the timing down. I believe that this has been mentioned earlier in this post, but the black box Boyers are sensitive to voltage. The Boyer MicroDigital and the TriSpark, the two brands I'm familiar with, are much less sensitive.

One last thought. If someone in the bike's history wired, or miss wired, the ignition switch and/or the toggle switch in the headlight such that the headlight and tail light come on with the ignition circuit, that situation will draw off considerable voltage.

Best.
Click to expand...
"you have made the k/s pawl engage with the layshaft gear the pawl lives in"

sir could you please explain that in knucklehead terms?
 
L.A.B. said:
Static timing is set at full advance. When kickstarting the ignition is (or should be) fully retarded.



Boyer "black box" Micro MkIII is, Micro MkIV isn't (although this could well be a MkIII box).
Click to expand...
It is an MKIV box from Carl Hokanson (ebay seller)
 
MarkDeaton said:
"you have made the k/s pawl engage with the layshaft gear the pawl lives in"

sir could you please explain that in knucklehead terms?
Click to expand...

He means push down on the kickstart lever until you feel the ratchet engage, then kick.
 
How I set the timing:

1) Put the bike in 2nd or 3rd gear
2) Put a screwdriver down the left plug hole, turn the back wheel until the piston is at the top
3) Watch the timing gauge and inch the rear wheel back in small steps until the mark is at 31
4) Ensure the white dot is directly under the commando static timing hole (what is the atlas static timing hole for?)
5) Ground the plugs against the motor, apply 12v and tap the black/white and black/yellow wires together quickly to ensure spark
6) Pray
7) Kick
8) Fail
9) Sit down, crack a wobble pop and cuss
 
MarkDeaton said:
"you have made the k/s pawl engage with the layshaft gear the pawl lives in"

sir could you please explain that in knucklehead terms?
Click to expand...

Sure.

With the k/s arm in the full up it has to move a few degrees before the pawl which is attached to the k/s shaft by a pin and spring loaded for engagement inside the layshaft 1st gear.

74 Commando Boyer Testing


74 Commando Boyer Testing


If you jump for the sky and throw your weight on k/s arm the pawl which is parked has to move off its cam to engage the gear it drives (bottom picture or link) will gain a huge amount of potential energy. When the pawl finally engages the gear that potential energy becomes kinetic. Over a relatively low number of such start attempts the slamming will ruin the pawl and offer a good chance of adding the gear to the shopping list as well.

My point is that knowing this you can engage both parts gently by making the beginning of your kick commence a tad before your weight lays on the most energy, at TKC (top kick center) to coin a new acronym.

Best.
 
Is that what the click is during kicking. After a couple of kicks there is an audible click and seems to be about a 1/4" jump in the kick lever like it is jumping past a notch if that makes sense.
 
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