Silk Motorcycles

Boyer ignition problem

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Arthur Farrow

Re: Boyer ignition problem

Oh joy or joys my silk is doing the retarding trick too on Boyer system

I'm using one of those silly over the top strobes that has delay settings etc and 2 stroke or 4 stroke settings and i wonder if that is confusing the readings

If i set at 2 stroke settings it is still firing twice as often as one might think it would as it has the lazy spark. bearing in mind some electrical systems do retard the spark as revs rise is this the issue?

I bought a basic flash - flash stroke with no fancy crap and we will see.

hendred

Re: Boyer ignition problem

I only have a basic strobe so don't know how the more sophisticated ones work or how they are set up. However the electronic tacho is the same as for four cylinder four stroke (four sparks every two crankshaft rotations. Can the strobe be set for a four cylinder four stroke? If it can it might be wodth a try.

Arthur Farrow

Re[2]: Boyer ignition problem

These "professional" adjustable strobes are either 4 or 2 stroke and they do revs and clever things like delaying the strobe flash. ie if you need 30 degrees before TDC you dial in 30 and it flashes at TDC where most stuff is clearly marked. Too damn clever for me.

My bike was never fitted with a tacho and honestly no Silk owner needs one to time. My new strobe arrived today and I'll look at what it does tomorrow after a large English Whisky.

Arthur

------ Original Message ------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 09/09/2020 18:08:04

Subject: Re: Boyer ignition problem

I only have a basic strobe so don't know how the more sophisticated ones work or how they are set up. However the electronic tacho is the same as for four cylinder four stroke (four sparks every two crankshaft rotations. Can the strobe be set for a four cylinder four stroke? If it can it might be wodth a try.

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ukpco

Re: Re[2]: Boyer ignition problem

Arthur
I have a fancy strobe too and wondered whether it was giving the wrong result. I borrowed a basic strobe from a friend and got exactly the same result.

Smokey_Paul

Re: Re[2]: Boyer ignition problem

Administrator

Arthur gggrrrrrr have you got a brake cable now as I have a few genuine stock ones ?

Arthur Farrow

Re: Re[2]: Boyer ignition problem

Yes I had 3 brake cable made special. I have 2 available for sale but so far no takers which sort of makes me wish i had not ordered 3

Smokey_Paul

Re: Re[2]: Boyer ignition problem

Administrator

Sorry I didnt catch your post as I have about 5 ...opppss

Sent from my Samsung Galaxy smartphone.

-------- Original message --------

From: "Arthur Farrow [via Silk Motorcycles]" <[hidden email]>

Date: 18/09/2020 22:10 (GMT+00:00)

To: Smokey_Paul <[hidden email]>

Subject: Re: Re[2]: Boyer ignition problem

Yes I had 3 brake cable made special. I have 2 available for sale but so far no takers which sort of makes me wish i had not ordered 3

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hendred

Re: Re[2]: Boyer ignition problem

Be interesting to know the result of your test with the basic strobe. Is the Boyer retarding instead of advancing? If it is then that makes two in recent times.

Arthur Farrow

Re: Boyer ignition problem

Sadly I have gone down with a nasty chest infection and been out nearly 3 weeks

Improving and will advise ASAP

Sent from my iPhone

Arthur Farrow

On 28 Sep 2020, at 16:35, hendred [via Silk Motorcycles] <[hidden email]> wrote:

Be interesting to know the result of your test with the basic strobe. Is the Boyer retarding instead of advancing? If it is then that makes two in recent times.

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hendred

Re: Boyer ignition problem

Hope you are feeling better soon. Soon be time to put my Silk to bed for the winter. Out of interest, do you still have the original rectifier and zener diode to control the alternator output or a more modern rectifier/ regulator on your Silk?

Arthur Farrow

Re: Boyer ignition problem

Turns out my chest infection was Covid 19. None of the normal symptoms just like a chest infection BUT I have lost a stone in weight. Rubbish !!

I fitted a Wassel alternator 200W I think and a modern electronic rectifier . Why use anything else??

hendred

Re: Boyer ignition problem

Hope you are progressing in your recovery from Covid 19. My interest in this subject is that I have the original Lumenition ignition and at some point it will probably fail and will have to make some decisions about what to replace it with. Boyer/Pazon/Wassell systems offer a reasonably priced option. A new Lumenition system can be made to fit with some small changes to the base plate but requires a functioning mechanical advance and retard mechanism. A Newtronics (Piranha) could also be made to fit (they made a kit for BSA/Nortons at one time) which would require the mechanical A/R mechanism, but does offer the possibility of moving away from wasted sparks.
The Boyer system has been successfully fitted to several Silks with no significant problems reported and I am wondering why we now seem to have two systems with similar problems. Paul's Boyer was checked and tested and no fault found and the installation checked all to no avail. The Boyer Micro digital unit appears to be susceptible to RF interference which is why they require a 5k ohm resistor in the ht lead. Another source of interference could be the modern alternator rectifier/regulator putting high frequency ripple on the 12v system. I don't believe the old zener diode regulation would create a high frequency ripple and this could be the difference. Fairly easy to test the theory, just disconnect the alternator and see what happens. If it doesn't cure the problem I have run out of ideas!

Smokey_Paul

Re: Boyer ignition problem

Administrator

I now have about 12 working mk16 lumenition systems so should see most people out as not that many being ridden every day.

I also have a lumenition factory test set up which is rather interesting and a bunch of spares to repair when I am bored.

Sent from my Samsung Galaxy smartphone.

-------- Original message --------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

Date: 04/10/2020 10:39 (GMT+00:00)

To: Smokey_Paul <[hidden email]>

Subject: Re: Boyer ignition problem

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hendred

Re: Boyer ignition problem

Should have waited for your post! Makes my latest post on Lumenition Optical switches redundant.

Smokey_Paul

Re: Boyer ignition problem

Administrator

Not at all mate some may wish to upgrade or change, just lucky I have been speaking to an old Lumenition distributor from the 70s by shear luck and he is sorting me out all the systems he has left new boxes and returned spares.

I will take a picture later it's quite interesting to us nutters lol

Funny what people store and in this case very lucky. I will set up tested working pairs and only sell to Silk owners on attrition basis do no hoarding just in case.

Sent from my Samsung Galaxy smartphone.

-------- Original message --------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

Date: 04/10/2020 11:07 (GMT+00:00)

To: Smokey_Paul <[hidden email]>

Subject: Re: Boyer ignition problem

Should have waited for your post! Makes my latest post on Lumenition Optical switches redundant.

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Arthur Farrow

Re: Boyer ignition problem

So finally my son and I used a traditional strobe on it yesterday. One with fancy delay angles and shit was doing v odd things, bouncing about all over the place and the ignitions seemed to retard not advance.

We have a great video of it but its a bit BIG.

MUCH better result with a traditional strobe It's on full advance at tick over .3 inch BTDC quite reliably does not move at all when revved. Probably retards for starting then immediately advances, but you cannot see it...two stroke crank driven Boyer unit originally designed for a Norton twin driven by the camshaft therefore running twice as fast as it normally would . On the Norton it goes to full advance about 3,000 rpm so on the Silk two stroke its 1,500 rpm.

The bike starts v well too sometimes with a small kick back. On the road it does not have a lot of low down grunt. I guess it would be nicer with a decent advance curve more suitable to the revs.

Any ideas anybody ?????????

On a couple of occasions whilst letting the revs really drop (with the throttle stop wound out) the ignition suddenly changed to firing AFTER TDC by a big margin. . This got us really puzzled until examining a video we took ..the damn thing must have hit a compression v slowly and REVERSED direction of motion!!. Sounded just fine too.

Smokey_Paul

Re: Boyer ignition problem

Administrator

Arthur in about a week I will have MK16 original new old stock tested Lumenition standard ignition systems that need no mods and are as originally fitted.
I also have MK12 systems for the earlier mk1 Silks and I am working on a MK17 upgrade also.
Will confirm once they are ready but this solves all the issues

Arthur Farrow

Re: Boyer ignition problem

That sounds nice please do let me know

However my mechanical advance retard Is in pieces and I was not sure how it went together and one spring had gone walk about

Anybody a spare ATD. ????

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Arthur Farrow

On 2 Nov 2020, at 23:53, Smokey_Paul [via Silk Motorcycles] <[hidden email]> wrote:

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hendred

Re: Boyer ignition problem

Arthur
If you type Boyer into the search box you will find quite a lot on this topic from 2014. Look for the posting on Jan 10, 2014 by Staffs (Clive Worrall). He had exactly the same results as you found from both Boyer and Pazon systems and also ended up with the engine running backwards. Under Special Boyer you will see George Silk had a special system made by Boyer to give a different advance curve and Boyer can supply these as a special order - need to check with Boyer if this is still the case.

There are two types of mechanical Adv/Retd units. one with two lightweight cast alloy bob weights and one with a single brass/bronze bob weight. I believe the earlier bikes had the two bob weight system. My bike has the two weight unit and had only one spring fitted when I got the bike. I got two springs from Andover Norton, part no. 06-8046, and they seem to work ok. My engine goes to full advance at about 2200 rpm.

Reading some of the old Silk articles in the Scott Owners Club website, some owners removed one of the springs to improve performance. That would cause the mechanical Adv/Retd unit to get to full advance at lower rpm. Maybe that is why my bike only had one spring fitted when I got it. My bike doesn't have a lot of torque at low engine speeds. Until recently it was running about 3 degrees retarded and it was a dog below 4,500 rpm. With the correct advance it is much better and is quite pleasant to ride with a lot more low engine speed torque. Just not as much low engine speed torque as a 650 four stroke twin. I found A Graham Bell's Two Stroke Performance Tuning book very helpful in getting a better understanding of timing and exhaust systems on two strokes. My Silk has a 17 tooth gearbox sprocket as fitted from new according to the handbook. Some bikes appear to have had 18,19 or 20 tooth sprockets. The smaller sprocket helps with low engine speed performance but makes it feel very "busy" at speed.

Dirk

Re: Boyer ignition problem

Hi,
i just got ready fitting the boyer to my no.112/114.
Mine is advancing as you rev up.
I started with .2“ advance with poor power, am now at .3“ with much better power.
BUT, it kicks back like a mule, no matter if set at .2“ or .3“ !?
....i cannot remember if my (all the others?) Silks tend to kick back in stock form (lumenition),
cause it is 5 years since i last drove it (shame on me the the boyer conv. took so long)

Also i am not sure if the engine is pinging under load esp in high gear.

Is there anybody in that forum who uses the boyer for more than a test ride?

yours
Dirk

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