Recent comparison new power arc vs tri spark

Ashman
Its a new option for those who want it. Now you have a choice. Some are put off by the Commando side mount mag because there is no retard. This makes the magneto more attractive to those who are concerned about fixed advance and now a few more may go with the mag. No one is forcing anyone to do it.

There are two possibilities I see relating to the fixed advance magneto question(and, I'm sure, a whole lot more that I don't see). One, since Ashley fixes the issue of knock, or kickback on startup and pulling from very low rpm, by slightly retarding the advance till it does not occur, he may not be getting the benefit of full advance at high rpm when it could be used -- yet not noticing the loss of power because it is actually slight on less than a "full house" race setup. Or maybe none of us, unless we are competing with someone down at the local red light would notice it either. Or, maybe, since the reason for large advance is the time it takes the flame front to spread, especially in a high rpm situation with the intense swirl of gasses and rapid compression in the combustion chamber, the greatly increasing intensity of the magneto spark with increasing rpm partially offsets the need for such a large advance. Perhaps to the point that the top part of a magneto advance curve would, beyond a certain degree of advance, only bring a marginal increase in power. I know the reason for advance and the dynamics within the combustion chamber are far beyond my ability to analyze just sitting here typing away with no hard experimental evidence. Considering something absurd, obviously you would need NO advance if you could instantly distribute intense spark through out the entire volume of the combustion chamber. So, stating the obvious, degree of spark advance is not something once discovered and now set in stone. But if someone actually has information about this, experimental or otherwise, I'd be very interested. Just revealing my lack of knowledge is all.

Does the increased spark intensity that comes of increased magneto rpm increase the speed of propagation of the flame front in the combustion chamber? Thus reducing somewhat the need for such a high advance. So you could get away with retarding the spark a bit for easier starting without loosing too much on the top end.

Apologies. The second post above is a condensed version. Reason is I thought the first disappeared.

jseng1 said:

Ashman
Its a new option for those who want it. Now you have a choice. Some are put off by the Commando side mount mag because there is no retard. This makes the magneto more attractive to those who are concerned about fixed advance and now a few more may go with the mag. No one is forcing anyone to do it.

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Hi Jim

Thats all good as so many are so concerned about fix advance, to me it works great the way it is from start up, slow RPMs to flat out without missing a beat and of course carbies play a big part as well, both carbies and maggie must be tuned right, when I brought your PWKs you jetted them for the cam I was running and when I put them on it fired up first kick and with a few small adjustments they work so well together, the only problem with these carbies is sometimes float get caught up on the overflow cube being so close to each other, hopefully I have fixed that problem from your recommened advise, I have been doing a few other mods on my Norton at the moment and hopefully will be out riding it again soon.

Ashley

ashman said:

Hi Jim

...the only problem with these carbies is sometimes float get caught up on the overflow cube being so close to each other, hopefully I have fixed that problem from your recommened advise, ...

Ashley

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The occasional hang up with the floats on the PWKs turned out to be the float needle ribs catching on the cross vent hole in the needle recess. There are 4 ribs on the sides of the float needle. The corners of the ribs are too sharp and need a little rounding off. I was hitting them with a jeweler file at a 45 deg angle until I got the manufacture to redesign the float needles.

jseng1 said:

ashman said:

Hi Jim

...the only problem with these carbies is sometimes float get caught up on the overflow cube being so close to each other, hopefully I have fixed that problem from your recommened advise, ...

Ashley

Click to expand...

The occasional hang up with the floats on the PWKs turned out to be the float needle ribs catching on the cross vent hole in the needle recess. There are 4 ribs on the sides of the float needle. The corners of the ribs are too sharp and need a little rounding off. I was hitting them with a jeweler file at a 45 deg angle until I got the manufacture to redesign the float needles.

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Hi Jim

Do you stock these new float needles if so I might order some from you as last time it leaked I couldn't stop the flow of fuel out of the over flow, if you do I will PM you.

Ashley

Joe the orginal poster of this thread, sorry about the take over but you aren't having much luck with your orginal question about the new power arc vs tri spark with comparison, I throught you might get a few replies about that, I had a thread a while ago about the new JH maggies so maybe I should go back to that and add more to it as now there are more interest in the Maggie way, I am no longer interested in any ignition systems that rely on battery power, the extra weight of a big battery to a lighter bike and I know which way I want, my Norton is so much lighter than a orginal Commando and most of my weight is down low for better handling.

Ashley

Ashley, I like reading about all this concerning ignition systems. I thought through your success with a Joe Hunt mag and (see a long and boring post above) I've come to the conclusion that the intense spark from a mag at high rpm might require less advance to propagate the flame front in the cylinder. So setting it up the way you do, adjusting the timing until it's ok at low rpm or on start-up just might be fine. Surely some manufacturer has looked at this and can clear it up for me. Once that's cleared up, I'll know whether or not to get that power-arc.

Joe Schlaberdowski said:

Ashley, I like reading about all this concerning ignition systems. I thought through your success with a Joe Hunt mag and (see a long and boring post above) I've come to the conclusion that the intense spark from a mag at high rpm might require less advance to propagate the flame front in the cylinder. So setting it up the way you do, adjusting the timing until it's ok at low rpm or on start-up just might be fine. Surely some manufacturer has looked at this and can clear it up for me. Once that's cleared up, I'll know whether or not to get that power-arc.

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Hi Joe, I am not sure how it works as I am no tec person but I do like how the JHs work the more they spin the stronger the spark and understand what you say about the intense spark at high RPMs, like I have said before I set the timing at 28d static and if I get any kickback at all I just retard it ever so slitely, maybe if you like some more imput I am sure if you contact Joe Hunt themselfs I am sure they would answer your question, they are very helpfull.

Ashley

Every time I see a mag hanging off a timing cover, I think 'Great spark but what if it slides down the road and wipes out that hunk of money, along with - maybe - other timing side parts?'

Nah, electronic is easier, lighter, simpler, no points, no kickbacks, and a points cover is cheap.

But for that hanging off stuff, if I had Atlas timing internals, then I might try a magneto, per JS.

As for Power Arc vs Tri-Spark, all I can say is my Tri-Sparks has been almost faultless; as the instructions warned, a wire under the points cover broke because I failed to properly "pin" it with a piece of foam that they supplied. Easy fix at the side of the road. No experience with the Power Arc

C'mon, John! A magneto is THE way to go, definitely the bees knees!

Oh, wait, .it's not 1925 anymore...never mind.



Concur re Trispark - installed mine in'08; has required no attention at all since then.

Let's see. If you have a magneto and the circuits associated with the battery crap out, you ride home. If the mag craps out you can catch up on your reading using the Commando's parking lights. Given how little time I get to read I'd call this one a toss-up.

Mechanical advance/retard for your mag; good thing we had innovative engineers that brought us these wonders in the very early 20th century. Advantage EI.

The mag sits out on the right side begging to be smashed off, add the mechanical advance/retard pieces and your mag can double as a right hand side stand. I grew up riding real horse power on English saddles I, actually, can't mount a motorcycle from the right; I don't have similar restraints when the lights go low and the bedroom door is closed...

I get the stand-alone ignition thing (the Prince of Darkness signs a cease-fire with Fairbanks-Morse), but even rocks turn to dust over time. When your magneto equipped Commando quits miles from home you are either out of gas or your mag went on holiday, in either case you walk, unless you are carrying a book you want to catch up on.

The magneto has how many parts? From what I gather the cost of a new magneto would allow you to carry a replacement electronic ignition, that has, maybe, 2 or 3 parts?

I have asked many times which paradigm creates a greater spark and have yet to get a solid answer, and at this point it makes no difference to me, but I usually carry the book I'm into, just in-case...

A bore hog has two rows of titties, just in-case...