Contact breaker drive shaft play

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Oct 24, 2019
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Hi All, I’m setting up the ignition timing on my P11 and noticed the contact breaker drive shaft has in and out play. I think this may be upsetting the Boyer system. Is this possible and if so, how can I reduce this play?
 
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Where exactly are you installing the Boyer rotor in your scenario?

Usually the Boyer rotor is installed on the timing side end of the cam shaft with all the points hardware and AAU removed from a Commando style timing cover. Play on the end of the cam shaft should not be not enough to upset the ignition in any significant way. Is the Boyer rotor moving in the taper? If so, something isn't right, and I have zero experience making that tight, so won't make up a way to fix it.

I do run Boyer ignition on a P11, but my timing side was modified to support a Commando 2S cam and ignition components. Cam was shimmed for end play. If you have a Commando engine installed in your P11, it would be the same more or less.
 
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Where exactly are you installing the Boyer rotor in your scenario?

Usually the Boyer rotor is installed on the timing side end of the cam shaft with all the points hardware and AAU removed from a Commando style timing cover. Play on the end of the cam shaft should not be not enough to upset the ignition in any significant way. Is the Boyer rotor moving in the taper? If so, something isn't right, and I have zero experience making that tight, so won't make up a way to fix it.

I do run Boyer ignition on a P11, but my timing side was modified to support a Commando 2S cam and ignition components. Cam was shimmed for end play. If you have a Commando engine installed in your P11, it would be the same more or less.
Hi Shwany, Thanks for your reply. On the P11 the points box is behind the right cylinder. The drive for it comes from the contact breaker chain under the timing cover. The rotor with the magnets is screwed onto drive shaft. This has movement in and out, causing the magnets to move further or closer from the stator plate. I figure it's retarding or advancing the spark , depending on whether it's in or out. Uneducated guess, really. I'm getting an itermittent weak spark on the left cylinder,.
 
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My P11 had a big single points Lucas Magento on it originally. Separate gears and chain for the magneto drive with the AAU on the inside of the timing cover. I'm not familiar with what you have. Boyer didn't make anything bolt on for the old magneto drive setup. Might be able to get one of the stubby magneto replacement points enclosures now, and get rid of the AAU, but that wasn't around in kit form when I did the Boyer. If I had it all to do over again, I'd put a Joe Hunt magneto behind that right cylinder and use the alternator, reg/rect box, and a battery for the lights. I could do it now, but too much thinking and finding parts would be required. Besides I've got a one kick start bike after I get enough fuel in to the combustion chambers. No sense messing with it.

Somebody out there must have an answer for your situation based on real world experience. All I have is pointless stories. :)
 
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Hi All, I’m setting up the ignition timing on my P11 and noticed the contact breaker drive shaft has in and out play. I think this may be upsetting the Boyer system. Is this possible and if so, how can I reduce this play?
If it was side to side play, which yours hasn't, the brush/ shaft has become worn.
A small amount of up and down play (.010 to .020 thou) is normal, but can be reduced by stripping the shaft out and inserting a brass/bronze washer to reduce it.
 
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