Timing setup for a new Boyer Bransden MK3 electronic ignition system on a MKIII Commando

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Hi All, I’m setting up my timing with a new Boyer Bransden MK3 electronic ignition system on my MKIII Commando. The instructions say it must be timed on the 31 degree BTDC mark up to 5000 rpm using a strobe lamp. If I set it at 5000 rpm on the 31 degree BTDC mark it sounds very rough. If I set it at 3000 rpm on the 31 deg mark it sounds just right. The more I rev it the more the timing retards and shifts a good 10 degrees through the rev range. There must be a sweet spot somewhere but has anyone had the same challange and how have you addressed it please? I have installed the rotor and the stator plate exactly to Boyer’s instructions while the static timing mark is positioned on the 31 degree BTDC mark. Plus, I’ve gone back and double checked that everything is set just right in accordance to their instructions. Any advice as to where exactly and at what rpm it should be calibrated would be gratefully received. Cheers!
 
I’m setting up my timing with a new Boyer Bransden MK3 electronic ignition system on my MKIII Commando.

I would expect a relatively "new" Boyer Bransden to be the MkIV.

The more I rev it the more the timing retards and shifts a good 10 degrees through the rev range.

It should be advancing (rotor mark moving up the timing scale towards 31 degrees) as you rev, not retarding?
 
I would expect a relatively "new" Boyer Bransden to be the MkIV.



It should be advancing (rotor mark moving up the timing scale towards 31 degrees) as you rev, not retarding?
apologies... advancing it is!
 
If it is a MK3 Boyer and not a MK4 Boyer then do not fit it, it will create too many backfires and ruin your sprag. MK4 is better on a MK3 850 Commando.
 
As it's an 850 Mk3 Commando have you checked the position of the rotor mark on the timing scale with the crankshaft slot?

Timing setup for a new Boyer Bransden MK3 electronic ignition system on a MKIII Commando

Timing setup for a new Boyer Bransden MK3 electronic ignition system on a MKIII Commando
 
I fitted a Boyer MK 4 several years ago now , it is a much better functioning unit than the older Boyer I removed ....
 
It was while ago , that I followed the instructions provided ....
 
The ignition timing degree scale on the outer chaincase can easily be up to six degrees off.
Even more so on the MK3 as it is mounted on slotted holes which give you some adjustment.

As Les suggests, using the mark on the crank on the timing side inspection plug will allow you to see how far out your scale is on the primary side.
Note this will show you where 28 degrees BTDC is, not the 31 that you’ll be setting your Boyer at.

As others have said, double check on the model - the Boyer MK3 is not good for your starter’s sprag and would not be recommended.
 
The ignition timing degree scale on the outer chaincase can easily be up to six degrees off.
Even more so on the MK3 as it is mounted on slotted holes which give you some adjustment.

As Les suggests, using the mark on the crank on the timing side inspection plug will allow you to see how far out your scale is on the primary side.
Note this will show you where 28 degrees BTDC is, not the 31 that you’ll be setting your Boyer at.

As others have said, double check on the model - the Boyer MK3 is not good for your starter’s sprag and would not be recommended.
Sound advice thank you!
 
I never set timing on MKIII's over 28 degrees BTDC. Doesn't matter what ignition system you use. Too much chance of a kick back and you can't tell the difference on a stock bike anyway. Keep to what the factory recommended in this case.
 
@milfordite I am sure that Boyer Bransden advise 31 degrees BTDC after a lot of research and testing.
They wouldn’t call it out in their instructions as different to factory timing if there wasn’t a good reason for it.


Timing setup for a new Boyer Bransden MK3 electronic ignition system on a MKIII Commando

I feel that following the instructions is probably the best way.
Just my opinion, obviously.
 
I never set timing on MKIII's over 28 degrees BTDC. Doesn't matter what ignition system you use. Too much chance of a kick back and you can't tell the difference on a stock bike anyway. Keep to what the factory recommended in this case.

@milfordite I am sure that Boyer Bransden advise 31 degrees BTDC after a lot of research and testing.
They wouldn’t call it out in their instructions as different to factory timing if there wasn’t a good reason for it.

My Mk3's ignition (Pazon Sure-Fire) is also set to 28-29 degrees BTDC as a precaution against kick-backs.
 
FYI The primary cover degree plate on a MK3 is adjustable having screw slots and therefore can be loose or misadjusted
 
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