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set timing with boyer on 650 ss


Hello i have 650 ss 1964 and i have boyer(placed on magneto place) same stile as on commando how i can set ignition timing? thanks




To do it correctly you need to remove the primary cover and  mark up the alternator using a timing disc  and set the timing at around 5000 rpm using a strobe. What a faff. Thats why i stayed with points ,fag paper and a stick.


Hello now to set the timing there is a set prosiedure starting with the removal of all rocker covers and primary cover and finding a accurate top dead center on the firing stroke and engine fires once every 720 degrees or two turns of the crankshaft  normly with the magneto in place you have to use a pointer and a timing disc and find TDC on Firing Stroke then set it back to 32 degrees before TDC but with electronic ignition you take off 2 degrees making this 30 degrees before TDC and set the timing at this,  and the reason for removing the rocker covers is so you can see that all the valves are in the closed position and the next stroke will be the firing stroke were you will be timing it to ,  yours Anna j 


The 650SS is a parallel twin, so it fires on every revolution prior to top dead centre. The boyer is of waisted spark type, i.e. sparks both plug at the same time. :-)

As said in the manual: "important that TDC should be accurately determined to start from."

You can't find TDC just by feeling where the piston change direction. As a couple of degrees movement only gives a very small movement of the piston. So you shall make (or buy and modify) a stop fitted in the spark plug hole. Stopping the piston at least 30 degrees from TDC. Them rotating the engine forward and backwards to the stop. Then position the timing disc so that numbers are equal. Will give you a fairly accurate TDC. Some bikes have a line on the alternator rotor and a pointer already fitted. Have not checked that on a 650SS yet, but made a similar thing on my Manx.


Hello no matter which engine you have twin singles four-cylinder 6 cylinders or 8 cylinders Ever Four-stroke engine fires in the same way  after two turns of the crankshaft on a Heavy twin there alternate within every  720 degrees thus  making this every 360 degrees on two alternate strokes only one cylinder fires the after 360 degrees the other fires   and to find TDC look at your rockers witch all should be in the close position, then time the engine from there  and make sure you have the left-hand cylinder Or Drive Side cylinder  in firing position         Yours  Anna J


The original poster is asking about setting with a BOYER electronic ignition. As Mikeal has said, these  operate on the "wasted spark" principle, i.e. they fire on the exhaust stroke as well -  both coils fire together each time so it really doesn't matter whether it is on the compression or exhaust stroke when timing it. What you are advocating only matters when you sre using a magneto or a distributor.


Tomis, I have an Atlas with a boyer fitted in a Commando timing cover ( don't ask, long story ) I set up a home made timing disc so I could time my engine using a strobe light. This is my method.

I cut a disc out of thin MDF board which is a slightly smaller diameter than the stator. I then marked the center of the disc and the relevant degrees before top dead center 28,30,32. using a small protractor. You could go online to Matchless clueless he has a downloadable timing disc. By reducing the size you could achieve a printed disc slightly smaller than your stator. This could be glued to a stiff cardboard disc.

You will then have to cut a hole so the disk can be mounted using the rotor nut to secure.Now set the the engine at top dead center using a probe through the spark plug hole or better still use a dial gauge. Put a straight edge along the pointer on the rotor and mark this on the stator with a thin white marker pen.

Once this has been done clean up the area where the timing marks will go with some solvent, turn the disc so TDC aligns with the rotor mark. Then use the white marker and a short straight edge to mark your timing marks. These should be about 5/16 " long. Remove the timing disc and with a fine hack saw cut a shallow cut into the stator where the marks are. Next clean the area again and then with some oil based undercoat paint the cut area, then wipe the paint off leaving the paint in the cut area.

Once dry you can time your engine. As I have a belt drive I can remove the outer primary very quickly with no mess. To time the engine you will need the help of another person. I didn't have a tacho at the time so revs were guessed. When I later fitted a tacho and checked the timing, it was close enough.

Although doing the timing on your bike will be messy, once done you won't have to repeat very often. I hope this makes sense, I did this in 2008 !

NB The timing disc needs to be smaller than the stator so as to allow you to mark the timing marks on the stator. You may want to write 28,30,30 on the stator with your marker pen. GOOD LUCK

Anna - what you really mean is that each CYLINDER fires at 720 degrees not every four stroke ENGINE.

In reply to by george_farenden


Hello now as for timing you have set up the drive sides timing up first no matter what the ignition type it is magneto or electronic or nothing else will be run Anna j


Anna.. you keep posting this but it makes not a jot of difference which way you set it. If you have a mag and want to look original then by all means do it the right way. But if it's the wrong way it will work just as well, and it would be lunacy to dismantle the timing and start again. The universe doesn't care about left and right unless you are a nuclear physicist. With an electronic system one lead goes in series through two 6v coils  and it doesn't matter which coil it goes to first!



It is obvious you don't have a Boyer system.

It makes absolutely no difference what cylinder you use. It is a 360°twin, the coils fire every TDC on BOTH cylinders. The pick ups are fixed to the back plate, which you rotate a little to set the timing. There is NO independent adjustment for each cylinder.

I will say it is easier to use the drive side as that is where the alternator rotor is, and it is the side of the bike where it is easiest to access the Boyer holding 'points housing' on a 650 or Atlas, but there is absolutely no reason whatsoever why the timing couldn't be set on the right hand cylinder only.

If you have a Commando with the Boyer on the exhaust cam, it is probably easier to use the right (timing side) cylinder as that is the side where you need to be to set it up.

Regards, George 


Andrew Westmore i have same on my domi 650ss stroboscope i have i use them on my commando but here there are no marks i try it.


I hope it works for you. From memory you can set up the pickup plate on the boyer so it is close to the correct timing. This will allow you to start your bike and proceed to get the timing exact by using the strobe light. You will need an assistant to hold the revs at the suggested level to set the timing.

I also fitted a dual output coil so I could get rid of the two coils. This coil is smaller and made starting my Atlas much easier. I mounted mine on the the mudguard under the seat away from the oil tank which can get very hot. Tri spark sell them.

 let us know if you are successful.


hello with magneto or  electronic ignition you have to set the engine on the left hand firing stroke or it will kick back or not run at all  Do do not even try to tell me how to suck eggs  I have been around engine twins   too long  so 52 years  in  all   Yours  anna j


You truly are wrong and yet you either do not believe it or cannot accept it.

I'll try for the last time. A BOYER DOES NOT OPERATE LIKE A MAGNETO.

The Boyer works, as David and I have said, on the wasted spark principle. It will fire BOTH cylinders at the appropriate firing position,  as it fires both coils together. Many (myself included) run a single, twin outlet coil, so they have to fire simultaneously. If you don't understand that, please say so. It DOES NOT MATTER which cylinder you use when setting up a Boyer. It will run 100% happily having been timed on the timing side cylinder.

Regards,  George Farenden, who spent 42 years designing, developing and calibrating internal combustion engines in the car industry. 99% 4-stroke.


Here is a photo of how I set up my Navigator with Boyer ignition, won't be any different for a heavyweight.   Find TDC, doesn't matter which stroke by the positive stop method described in the workshop manual.  My timing disc is adjustable so rather than move the pointer I can move the disc.

This really is the only way to find TDC, its the crank shaft that determines TDC, not the piston.  Forget the idea on guessing it with something down the plug hole even though people will say it "works for me".

Set the engine at the appropriate BTDC.  Then follow the Boyer instructions for static timing, usually ends up somewhere handy.  The use a strobe for final setting but be careful of dangling wires and an exposed primary drive. 

As  has been said, doesn't matter which stroke or cylinder the engine is timed on, with the Boyer it will fire every stroke.


Oh dear, a few contributors have got into arguing with Anna. 

I doubt Anna understands the term 'wasted spark'. Her manxman has a magneto as she is always telling everyone.

Even at club meetings she will tell you what Electronic ignition to use without actually using the said E.I. system. Then saying 'I don't need E.I. as i have a magneto'

She purports to be a marine engineer. If shes a marine engineer I'm the king of Siam. If you call her out on this she says her papers went down on a ship that sank in the channel that no one has heard of.

Lloyds of London have no record of said ship or shipwreck.

I could go on

My advice is to take everything she says with a big pinch of salt. 




Tomis, I pulled the outer primary off my Atlas and took a pic of the alternator " ATTACHED". It was over 12 years ago that I marked the stator, memories fade ! Here is my revised suggestion.

Go online and go to Matchless clueless.Go to his free downloads and select timing wheels for 350 & 500 models. Print it off. Ignore the valve marks.

Remove the rotor off your bike, place the print onto a metal surface ( I used a filing cabinet ) and lay the rotor on top.

Centralize the rotor on the print using the red circumference mark. Then rotate the rotor so that the mark near the key way lines up with T.D.C. on the print.

Next place a steel rule or a laser across the rotor so as the red mark labeled "close" lines up with the 30 degree past B.D.C mark. Now with the finest white marker pen you can get, mark this line onto the rotor This will be 30 degrees before T.D.C. You can also mark 28 & 32 while your at it. Also mark the T.D.C groove on the stator.

Reinstate the rotor onto your bike and with the plugs out rotate the engine to T.D.C. I put the bike into 4th gear and rotate the rear wheel back and forth.Then insert a screw driver into the plug hole ( the rough way ) or with a dial gauge, set the pistons at T.D.C I fix a longer prob on my dial gauge so it reaches the piston.

Once this is done all you need to do is transcribe the rotor marks to the stator. Remove the rotor marks except the T.D.C one as you no longer need them. Your motor is now ready to time with a strobe, I hope, other scribes may disagree!

Note in the attachment the rotor isn't at T.D.C


it make no diffrence hello with magneto or electronic ignition you have to set the engine on the left hand firing stroke or it will kick back or not run at all Do do not even try to tell me how to suck eggs I have been around engine twins too long so 52 years in all Yours anna j


You are so wrong Anna and it's such a shame that you don't read what anyone else says and take it into consideration - it seems your views are set in concrete!

So please refrain from spreading misinformation, especially on a forum that could be read for many years into the future!

hello  no matter  if you using a electroic ignition IE wasted spark you first have set up your Ignition on the firing stroke with all valve closed and electronic ignition system do not time themselfs   Or you spark will spark anywhere,  And please keep your other comment to your self   Yours  Anna J


Please let's have a truce. Tomas asked a simple question. The standard handbooks do not explain timing with an after market device. If you follow Anna's instructions you will get the desired result. And indeed if you get another bike with standard coil or magneto, you will still get it right. But is a parallel twin. Two opposite handed single cylinder engines working side by side. When one is on compression, the other is on exhaust. And because both plugs spark at the same time, it does not matter which one is which. Every time each piston approaches top dead centre its plug will fire, because it fires on exhaust as well as power stroke. Presumably the spark plugs last half as long as a result.


Thanks  all for ansvers.

Boyer realy fired on both cilinders in same time. i have rev counter on my domi 650 i will try set up.

sory for my english I am from Czech republic some times is hard to understand technical words.for me. Have a nice day



I've used this info for my Dommie and Commando. I set the timing at 23 degress btdc @ 3,000 rpm as I find it less stressful and it helps keeps the noise down a bit (I have close neighbours) and do a quick check at 5,000 rpm to verify.

As in the text, I find this works great.


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