Boyer Stroboscope 3000 RPM or 5000 RPM

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Norton-Villier

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Hi guys, Do you have to set the stroboscope timeing with a boyer ignition at 5000 RPMs or can you set it at 3000 RPMs as the shop manaul says? THANKS Phil
 
Boyer Say's

23. Start engine and time with a stroboscope to 31 B.T.D.C. (28 DEC. with standard ignition) with the engine
running up to 5000 r.p.m. This is done by moving the ignition stator plate. If the timing is not
obtainable before the end of the adjustment, the magnetic rotor will have to be slackened off and moved a
small amount until the correct timing can be obtained.

I do what Boyer says to do.

I usually tie a rope around the front tire and anchor it to my van cause it REALLY moonwalks at that RPM.
 
Norton-Villier said:
Do you have to set the stroboscope timeing with a boyer ignition at 5000 RPMs or can you set it at 3000 RPMs as the shop manaul says?
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The workshop manual instructions are intended for the original points ignition with its mechanical auto advance that should be fully advanced by 3,000 RPM, the Boyer advance curve is different to the mechanical auto advance, therefore a Boyer ignition doesn't reach full advance until somewhere between 4,000-5,000 RPM, so you need to check it at 5,000 RPM.
 
the magnetic rotor will have to be slackened off and moved a small amount until the correct timing can be obtained.
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Only if you run out of stator adjustment.

From my own experience I've found 850's like a bit less advance probaby due to the crap fuel available etc. Has anyone tried setting the ignition advance on a dyno?

Cash
 
" the Boyer advance curve is different to the mechanical auto advance"

It is but it shouldn't be! ;)

"therefore a Boyer ignition doesn't reach full advance until somewhere between 4,000-5,000 RPM, so you need to check it at 5,000 RPM. "

Yep...WRONG advance curve for the engine (actually for ANY 4 stroke engine used on the street). For better performance at all RPM a properly operating points/aau are superior. For points/AAU performance plus the convenience of electronic the Trispark is a good choice.
 
THANKS GUYS,I had my wife hold it at 5000 RPMs. Took five trys but we got it. She got the first ride this year, backwards. I think she felt good about being able to help. Look out Debby. She loves to ride to. Phil
 
She got the first ride this year, backwards.
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Take it off the stand and your wife won't have to chase it around.

You lucky b***er mine won't come any where near when I'm messing about with the Commando. I shouldn't complain though coz she's coming with me on the Commando to Assen.

Cash.
 
Cash, She was afraid she couldnt hold it up and I was OK with that. Now that I have it set at 5000 RPMs dose anyone think if I took it up to 3000 RPMs and check the timming mark that I could us that mark as a reference for next time? Phil
 
Yes that would work for that box, if you change the box then check at 5K again as on a boyer the advance cure has differences between boxes as shown on Dave's Altantic Green site.
 
THANKS kommando, I have the same boyer box to put on my other 74 850 So I can us the 3000 RPM degree reading I get off the 75 850 and apply it to the 74 850? Phil
 
I've got rubber matting on my workshop floor, and with my Commando on its mainstand, I can rev it as hard as I like on that matting and it doesn't move, unlike revving it up with the stand on a solid surface.

So try placing a (reasonably thick) rubber mat under the main stand before doing strobe checks.
 
Norton-Villier said:
THANKS kommando, I have the same boyer box to put on my other 74 850 So I can us the 3000 RPM degree reading I get off the 75 850 and apply it to the 74 850? Phil
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From other threads on this forum, the Boyer will be 7 Degrees short of maximum advance at 3000 rpm. At 4000 rpm the ignition will be 2 degrees from the maximum. But it does vary a bit between units, so the closer to 5000 the better.
 
When you are doing your timing watching the line move under the strobe as the revs proceed you will see the line stop moving to the eye. (It does continue to advance but slowly) When it stops moving it should land on a corrected 31 degrees (Boyer) 28 (Tri-Spark) you don't even need an RPM gage? Just your ears and eyes, if you are afraid to rev the bike to 5000 or 6000 you need to think that through. You are setting the max advance to land on a point that will not burn a hole though your piston. The retard is just for starting and a product of the maker (arbitrary).
 
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