Not open for further replies.
Jun 3, 2005
Could someone advise me on the correct strobe timing for an 850 Commando fitted with boyer elec ignition. I have been told that it is best checked at 5000rpm but this seems a bit high; is there any settings for lower down in the rpm range.


5000 rpm is correct, the bike will have no issues as there is no load, you will however as the engine is directly linked to the center stand. So have a helper to hold the bike and stop it moving :D
Yes, a Boyer needs to be checked at 5000 RPM (31 degrees BTDC @ 5000 RPM for a Boyer).
When I time mine, I have my son sat astride it, with both wheels on the ground, and he revs it to 5,000 rpm whilst I point the strobe. It doesn't vibrate across the floor then.
Yes, don't attempt to time it at 5,000 rpm on the center stand. I usually put a block under the sidestand and have someone handle the throttle and watch the tach. You don't need to hold it there long. Just rev it as you watch the timing mark until it achieves 5000 rpm.
If you don't like timing the bike at 5000 (and I don't) time it at 5000 the first time, then check timing at a lower rpm and use this value for subsequent timing checks.
Doing it at 5000 is best but at lower revs you can get big variations with Boyer analogue ignitions. I measured 24 deg @ 3000 on mine with 31 @ 5000. I now have a Pazon which gives 28 @ 3000!! The original points setup was about 28 @ 3k but that would vary also. You might have a Boyer which gives 26 @ 3000 and could be overadvanced at 5k. Best to plot at 2000-5000. (you can't read marks accurately under 1500 which is about 15-16 deg).

I have recently fitted boyer on my '74 commando 850 and have trouble trying to strobe the timing.
I can't seem to get it to advance when I increase from idle to 3000rpm.

If I set it at 25 degrees at idle it also reads 25 degrees at 3000rpm.

I know your supposed to check it at 5000rpm, but I've recently rebuilt the motor and don't want to rev it that much.

Any one had similar problems?
If your rebuilt bike won't take a quick rev to 5000 you didn't build it right. The engine is made to operate at 4000 all day.
But more to the point at 5000 the movement of the line under the light of the strobe slows to a stop seen by the eye. It should land on 31 degrees.
Trying to hit a moving target by holding it right at 3000 while reading and adjusting is worse for the motor IMO. It takes longer so more danger of heat taking a toll. You would still need the double check it at 5000 anyway.So even if you rev past 5000( easy to do)) it still should stop moving by the time you hit 5000. So at 6000 it would still be at 31 or so degrees. The amount of advance after it stops moving by eye under the strobe is small. Not even seen by most. It is there as a quirk of the design in an analog Boyer as explained by our friend Dyno Dave at the Michigan National rally. It would be more ideal if the timing retarded just a bit at about 7000 rpm. That would need a better Boyer with a designed timing curve.
Do you all know that Boyer has finally responded to the better design of Pazon by releasing prototype ing. that can operate down to 7Volts or so like the Pazon already does.
Thanks for your advice Norbsa,

But what I really want to know is should I see the boyer ignition timing advance when I steadily increase the revs from tick over to around 3000rpm?

For example if it reads say 15 deg at tick over should it increase to say 25 deg at round 3000rpm?

At the moment I see no advance whatsoever within this rpm range, is this normal with Boyer?
Try switching the trigger leads.It sounds as if you have them switched (very common) The colors Black with a white tracer and Black with a yellow tracer look the same after the years go buy. Yes, it should move under the strobe light in that rev zone. Also, yes the spring goes inside the OPRV piston.
Hi Norbsa,

I'm pretty sure the trigger wires are correctly wired at the pick up plate, but I'll go and swap them around and try the strobe lamp on again and see if I get any advance.

Performance seems ok on the road, but motor tends to run a bit hot.
I'm using 100 octane benzin.
Hi Norbsa,

I switched the trigger leads at the stator plate (which were already wired to the correct colours). The motor gave an almighty spit back through the carbs and would not start!

I switched the wires back to the correct colours again and the motor starts no problem.

Any other suggestions ?
Only that you make sure you have a good common ground the engine(head) and Boyer, coils (coil) and positive battery cable need to be tied together. The strobe light should show the timing moving.
Ok, I've got some cable with croc clip ends I'll connect all those items you mention to a common positive feed and try another strobe check.
Yep I've tried fitting extra ground wires and still I have no ignition advance with the strobe light connected when I increase the revs from idle to 300rpm.

I decided to email Boyer with my problem and also quote my ignition box serial numbers.

Although I would welcome advice from any other Boyer users out there!
Thanks for that link to the wiring diagram, I dug out the original fitting instructions from Boyer which check out the same.

I removed an old Lucas Rita system and substituted it with the Boyer system so I was unable to follow the fitting instructions exactly, but my wiring seems correct though.

I'm beginning to think the problem may be with the transistor box. The numbering reads:- BOX 00017 03/10/17 (maybe it's not the correct box).

I mentioned the motor runs a bit hot, do you think that might be caused by the ignition not auto advancing?
Not open for further replies.