Boyer Ignition

[Staffs]

Can any one tell me how they are getting on with the Boyer kits they may have had fitted to their Silks.
 I have fitted three over the years and never had any come backs from the owners so assumed all was well.
 I am restoring a Silk right now that has had a Pazon fitted to it (not by me) that showed no advance and from conversations with various owners it appeared this system would not work on the Silk. I have removed the Pazon and Fitted a Boyer. When I checked the ignition with a timing light the results I got were exactly the same as the Pazon?
 I cant remember what results I got in the past but must have had some information from somewhere that said "Ah it'll be al reet" Fit and forget....I have!

Thoughts/Info required please

Ease of starting.  This one, first kick. Yours ?
Regular tick over.  This one, Yes fine,  Yours?
Top end performance. This one, I have spent too long rebuilding it to take it out and get it dirty this time of year.  Yours during a nice summer run with the bit between your teeth ?

Many thanks chaps.

[hendred]

I was looking at the Pazon Altair system for my Silk as it looks like there is little work to make the rotor fit in the space available.  I contacted Pazon to get the dimensions and asked about the advance curve for their units.  It seems they are at full advance at about 3000 rpm on a 4 stroke which translates to 1500 rpm on the camshaft.  Fitting the unit on the crankshaft of a Silk means that the unit would achieve full advance at 1500 rpm which is not much above my idle speed.  I also looked at programmable advance control boxes to get a better advance curve, just started to get too complicated at this point and as my original Lumenition system is working ok I left it there.  

From what I can make of it, there seem to be two types of mechanical advance units originally fitted to Silks; one with a single bronze bobweight and one with two light alloy bobweights very similar to the units on Triumph twins and Norton Commandos.  Is this correct and do the twin alloy bobweights fail as well as the bronze ones?  My Silk has twin alloy bobweights.    

If my unit fails I think I will make new bobweights and fit a modern Lumenition system - if it lasts another 34 years that will do me!

[Staffs]

As the Boyer is the same arrangement as the Pazon, The Boyer I suppose would also full advance at 1,500 rpm which is kind of what I see in the timing light beam, a slight flicker towards TDC when I allow the revs to drop but holding steady at my .2 mark with 2,000 plus rpm on the tahco. I will wait to see if a top end speed is posted to try and make more sense.

The bob weights you have are the earlier type. I have some but do not sell them just in case they fail as I obviously don't want to be responsible for damaging some ones ignition system. I think they fail for one or two reasons. First heavy handedness and secondly poor casting with weak spots caused by slag.
#
Not that many have detached themselves but a few did go all around the same time. This was a few years after production stopped so I don't think it is a given they will break.
The other type with the bronze bob weight, I think was done as an easier and cheaper way to make the advance and retard assembly.  Thanks for your reply.

[Hendred]

Thanks for the information on the bob weights.  Do you happen to know at what engine speed the mechanical advance units reached full advance?

My understanding is that the advance varies slightly depending on the porting used, with the Peter Green  porting advance less than for the earlier versions. On a system achieving full advance at 2000rpm I would expect high rpm power to be less affected than low rpm.  Having said that, looking at two stroke ignition maps they seem to reach full advance by about 2000 rpm and then reduce the advance at high rpm (usually above 6000 rpm so shouldn't be a problem for a Silk!).  Some Villiers engines had fixed ignition which worked ok too.   I suspect the ignition retard helps starting (reduces kick backs) and improves idling, after that it isn't too important whether full advance is achieved at 2000 or 3000 rpm.

It will be interesting to hear the experience of users of Boyer and Pazon units in practice.

[Smokey_Paul]

I think I agree with Hendred Bantams also work fine with fixed ignition including my old racing water cooled bike. I dont think the timing found would be an issue for normal road use and revs.

[Staffs]

While messing with the Silk today I tried to start it with a half hearted kick and it kicked back but started. The engine was running backwards. I guess this is one of the problems that this sort of ignition is going to give the Silk.
Out of interest has this been a problem for anyone else?

[hendred]

Interesting - I remember reading somewhere this was a problem with the Lumenition system and was cured by fitting a chopper plate with smaller cut outs.  Can't really do this with a Boyer or Pazon.

There is an interesting system from Electrex World, ref STK-102D, which replaces the Lucas alternator with a  self powered CDI unit.  This unit gives 21 degrees of advance on the crankshaft.  The downside is the generator part only gives 50W so would impact on lighting, upside no battery required for starting.  It would be interesting to find out if it would fit in the Silk alternator housing.  

[gasman]

I fitted a Boyer to my Scott and it looks like the ignition is actually firing the cylinder on both top and bottom of the stroke. The exhaust cracks and you can feel like a knock from the cylinder wall with your hand so much so the rollers for the big end seem to have been slipping in the housing, I have just refitted the big ends with new rollers and without doing anything else i'm going to fit points and condensers to see what result I have. At the moment the Scott would lose a race with a snail as no power to speak of. Results will prove whether the Silk will perform correctly with either Pazon or Boyer, I have my doubt's. Kev

[hendred]

The original Lumenition system is of the "wasted spark" type, firing at the top and bottom of each stroke and it works ok. The Lumenition ignition will give some "interesting bangs" if the kickstart is turned over gently! Boyer and Pazon are both "wasted spark" systems when fitted to a Silk too.  It will be good to hear from somebody with some experience of either of these systems in real road use.

[Staffs]

There is a man doing some tests for the Silks at the moment regarding Boyer. Let you know when there is something to report and when I think I understand.

[hendred]

Any feedback yet on Boyer/Pazon experience?

Thanks

[gasman]

After just replacing the Boyer with twin points and condensers I can say for a fact that the Boyer does cause the unburnt fresh mixture to fire at the bottom of the stroke, on a Scott anyway. The pinking type noise has gone, better acceleration, cleaner running, pain to start. I have now stripped the engine and found the bottom end was full of carbonised oily mess, this was after only 100 miles or so with a completely rebuilt engine. The stresses caused by extra firing i.e pinking type noise has damaged the gudgeon pin holes in the pistons, signs of wear on both big end pins, thrust washers worn etc etc. After finding this I am convinced that my first Silk suffered in the same way as the bottom end was always a dirty black mess. I have rebuilt countless numbers of two strokes in the past and never had this sort of problem. I can confirm without a doubt that my Silk will not be getting electronic ignition with a wasted spark, we will see how well that one runs. I'm saying no more on this subject apart from does anyone want the bag of powder that my old unit has been turned into, made me feel better.
Kev