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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Poor starting on new Amal and BTH Magneto
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<blockquote data-quote="davidd" data-source="post: 42303" data-attributes="member: 1177"><p>I think it is tough to make the transition from magneto to electronic ignition. As I mentioned above, I had trouble on the initial set up and it is difficult not to blame the ignition that you have not experience with. Many owners prefer the stock set up because they know how to make field repairs and there is not possibility of a field repair to an electronic ignition, unless it is a wiring issue. Congratulations to Minivin for catching an installation issue.</p><p></p><p>The issue of the spark is always tricky. The spark of the BTH appears to me to be a high frequency spark like the one I see when I try and TIG weld, but forgot to hook up the ground. It is not always easily visible (as Tim has mentioned.) I tried to find some information on the spark itself and I was not altogether successful. I was most interested in finding out if a big blue spark was an indication of anything that could provide useful information. If what I read is correct, the visible spark that we can see is not the spark that ignites the charge. This does not answer the question well, but it does suggest that the spark we see is the coldest part of the ignition. I ran across the following on the Briggs & Stratton site in the Ignition Theory section:</p><p></p><p>"<span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">Briggs & Stratton ignition myths:</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">A bright blue spark is best. A yellow/orange spark signifies weak ignition. Not true. Spark color determines virtually nothing. The hottest spark is ultraviolet which we can't see. Blue spark is cold in comparison to ultra-violet. Orange and yellow come from particles of sodium in the air ionizing in the high energy of the spark gap.</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">Laying the spark plug against the block and pulling the engine over can adequately test ignition coil output. Not true. The ignition coil will only generate enough output to jump the gap of the plug. When under compression, the plug requires twice the voltage to fire. This check is not an accurate test of the coil and can be misleading.</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">An armature air gap that is too wide will prevent spark. Not true. Well, sort of not true. Briggs & Stratton air gaps cannot be made too wide to prevent spark providing the coil is healthy and the engine is spun over fast enough. A wide air gap, say .030" will ever so slightly retard the ignition timing as the magnetic field takes longer to build within the coil windings."</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">If anyone knows more about the sparks, I think it might be helpful.</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">David</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p></blockquote><p></p>
[QUOTE="davidd, post: 42303, member: 1177"] I think it is tough to make the transition from magneto to electronic ignition. As I mentioned above, I had trouble on the initial set up and it is difficult not to blame the ignition that you have not experience with. Many owners prefer the stock set up because they know how to make field repairs and there is not possibility of a field repair to an electronic ignition, unless it is a wiring issue. Congratulations to Minivin for catching an installation issue. The issue of the spark is always tricky. The spark of the BTH appears to me to be a high frequency spark like the one I see when I try and TIG weld, but forgot to hook up the ground. It is not always easily visible (as Tim has mentioned.) I tried to find some information on the spark itself and I was not altogether successful. I was most interested in finding out if a big blue spark was an indication of anything that could provide useful information. If what I read is correct, the visible spark that we can see is not the spark that ignites the charge. This does not answer the question well, but it does suggest that the spark we see is the coldest part of the ignition. I ran across the following on the Briggs & Stratton site in the Ignition Theory section: "[SIZE=3][COLOR=#000000][FONT=Calibri]Briggs & Stratton ignition myths: [/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Calibri]A bright blue spark is best. A yellow/orange spark signifies weak ignition. Not true. Spark color determines virtually nothing. The hottest spark is ultraviolet which we can't see. Blue spark is cold in comparison to ultra-violet. Orange and yellow come from particles of sodium in the air ionizing in the high energy of the spark gap. [/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Calibri]Laying the spark plug against the block and pulling the engine over can adequately test ignition coil output. Not true. The ignition coil will only generate enough output to jump the gap of the plug. When under compression, the plug requires twice the voltage to fire. This check is not an accurate test of the coil and can be misleading. [/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Calibri]An armature air gap that is too wide will prevent spark. Not true. Well, sort of not true. Briggs & Stratton air gaps cannot be made too wide to prevent spark providing the coil is healthy and the engine is spun over fast enough. A wide air gap, say .030" will ever so slightly retard the ignition timing as the magnetic field takes longer to build within the coil windings." If anyone knows more about the sparks, I think it might be helpful. David [/FONT][/COLOR][/SIZE] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Poor starting on new Amal and BTH Magneto
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