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<blockquote data-quote="Magnetoman" data-source="post: 39605" data-attributes="member: 2806"><p style="margin-left: 20px"> <span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">Rather than individually reply to various posts, below I've cut/pasted things that caught my eye. Also, sorry in advance for formatting problems. This is my third attempt to fix them in 'Edit Post', but the editor keeps randomly removing spaces between some words.</span></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"></span></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>I think all a Joe Hunt mag would need is a modified cam to change the timing for say a <span style="font-size: 12px">Triumphs</span> 180 deg to a Vincents 205 deg...</em></span></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">The magnet for a V-twin is different as well as the cam. The magnet(s) is in two pieces cast asymmetrically in the <span style="font-size: 12px">aluminium</span> matrix to give the proper timing.</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>He had quite a few unhappy phone calls with both Ken Belland Perry Gearhart. Neither would warranty their work for a racer. After four or five failures, it was too costly to race these items, mostly in time and races missed. This is one of those issues where success depends as much on the people supporting you as it does on the rider.</em></span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">Sorry to speak ill of someone no longer with us, but my experience having Ken Bell restore magnetos for my Gold Star and Black Shadow~15 years ago is responsible for me deciding I had no choice but to repair them myself. I am not surprised at all that his magnetos failed on the racetrack, since they failed me in only ~50 miles of use on the street. Anyway, you can see what I learned as a result at:</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><a href="http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=446733#Post446733" target="_blank">http://www.britbike.com/forums/ubbth...733#Post446733</a></span></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"></span></span></span></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">As far as I can tell, this is the most extensive description of the repair of a magneto you will find.</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>My 'rebuilt' Lucas racing magneto stripped its splines and reset the timing at full engine speed which buggered the engine (twisted crank, seized pistons, all the usual). Never again will use the origina<span style="font-size: 12px">l </span>brass/steel combination</em> </span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">Somewhere I have an article from the late '40s or early '50swhere in an interview with a Lucas technical person he said, without actually condemning their rotating armature magnetos, that the reason they developed theSR1 because of the mechanical problems with the armature at the ever increasing rpms on the race track.</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>1). The capacitor was of too small a capacity for the high output so I used an external capacitor.</em></span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">The capacitance needed is determined by the inductance of the coil, not the output.</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>Did the armatures fitted to the KV-F TT mags have windings made of plated "Silver" wire..??</em></span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">Can you say more about this? I've never heard that anything other than copper was used, and don't understand why it would be, since copper has the lowest resistivity.</span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'"><em>the platinum points make a big difference here, clearly giving a much cleaner break with no after burning seen at the points.</em></span></span></span></p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px"><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Times New Roman'">As far as I can determine, platinum points were introduced in the early days (i.e. pre-WWI) because it was thought it had lower surface resistance than tungsten, which <span style="font-size: 12px">oxidises</span> more readily. However, in practice this is not an issue a tall, so I suspect Pt was kept in use basically out of superstition. Certainly, my measurements have not shown any advantage at all for Pt, and it does come at the disadvantage of eroding quite quickly in the presence of oil or gas <span style="font-size: 12px">vapour</span> (not that any of our bikes leak oil, or that Lucas seals aren't up to the task…). I address this in more detail, including a technical reference, in the link given above.</span></span></span> </p> <p style="margin-left: 20px"></p></blockquote><p></p>
[QUOTE="Magnetoman, post: 39605, member: 2806"] [INDENT] [SIZE=3][COLOR=#000000][FONT=Times New Roman]Rather than individually reply to various posts, below I've cut/pasted things that caught my eye. Also, sorry in advance for formatting problems. This is my third attempt to fix them in 'Edit Post', but the editor keeps randomly removing spaces between some words. [I]I think all a Joe Hunt mag would need is a modified cam to change the timing for say a [SIZE=3]Triumphs[/SIZE] 180 deg to a Vincents 205 deg...[/I][/FONT] [FONT=Times New Roman]The magnet for a V-twin is different as well as the cam. The magnet(s) is in two pieces cast asymmetrically in the [SIZE=3]aluminium[/SIZE] matrix to give the proper timing.[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][I]He had quite a few unhappy phone calls with both Ken Belland Perry Gearhart. Neither would warranty their work for a racer. After four or five failures, it was too costly to race these items, mostly in time and races missed. This is one of those issues where success depends as much on the people supporting you as it does on the rider.[/I][/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman]Sorry to speak ill of someone no longer with us, but my experience having Ken Bell restore magnetos for my Gold Star and Black Shadow~15 years ago is responsible for me deciding I had no choice but to repair them myself. I am not surprised at all that his magnetos failed on the racetrack, since they failed me in only ~50 miles of use on the street. Anyway, you can see what I learned as a result at:[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][URL="http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=446733#Post446733"]http://www.britbike.com/forums/ubbth...733#Post446733[/URL][/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman] As far as I can tell, this is the most extensive description of the repair of a magneto you will find.[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][I]My 'rebuilt' Lucas racing magneto stripped its splines and reset the timing at full engine speed which buggered the engine (twisted crank, seized pistons, all the usual). Never again will use the origina[SIZE=3]l [/SIZE]brass/steel combination[/I] [/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman]Somewhere I have an article from the late '40s or early '50swhere in an interview with a Lucas technical person he said, without actually condemning their rotating armature magnetos, that the reason they developed theSR1 because of the mechanical problems with the armature at the ever increasing rpms on the race track.[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][I]1). The capacitor was of too small a capacity for the high output so I used an external capacitor.[/I][/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman]The capacitance needed is determined by the inductance of the coil, not the output.[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][I]Did the armatures fitted to the KV-F TT mags have windings made of plated "Silver" wire..??[/I][/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman]Can you say more about this? I've never heard that anything other than copper was used, and don't understand why it would be, since copper has the lowest resistivity.[/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman][I]the platinum points make a big difference here, clearly giving a much cleaner break with no after burning seen at the points.[/I][/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Times New Roman]As far as I can determine, platinum points were introduced in the early days (i.e. pre-WWI) because it was thought it had lower surface resistance than tungsten, which [SIZE=3]oxidises[/SIZE] more readily. However, in practice this is not an issue a tall, so I suspect Pt was kept in use basically out of superstition. Certainly, my measurements have not shown any advantage at all for Pt, and it does come at the disadvantage of eroding quite quickly in the presence of oil or gas [SIZE=3]vapour[/SIZE] (not that any of our bikes leak oil, or that Lucas seals aren't up to the task…). I address this in more detail, including a technical reference, in the link given above.[/FONT][/COLOR][/SIZE] [/INDENT] [/QUOTE]
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