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Boyer Ignition testing and what to expect

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Boyer Ignition testing and what to expect

Posted by jonathan_newton at May 15. 2018

I have a BB mk 3 on a ES2 recently purchased which will not start. Valve timing good, compression good, carb and fuel good, battery good on optimate, ignition timing as good as you can set statically, but no sign of starting. It started (after a lot of fiddling) when I bought it and ticked over decently but since then it has been absolutly dormant. 

I read in the boyer documents that if you switch power on/off it should spark at the plug which it does, but not a fat blue   disharge, more of a white sparkle of short duration.  Is that what I should expect? 

If I kick it over with the plug out the the same feeble sparke appears but I am in doubt as to the strength of it to actually ignite the mixture.

I have advanced it further to get at least a miss fire or kick back but no joy. 

 Are there any other tricks or tips I should be looking for before I buy a magneto and be done with it!!!

 Any help appreciated....

Re: Boyer Ignition testing and what to expect

Posted by dan_field at May 15. 2018

Have you measured the voltage at the Boyer box? It needs to be at least 12volts.

Re: Boyer Ignition testing and what to expect

Posted by ian_soady at May 16. 2018

I'm always unsure about what constitutes a good spark. The modern BTH magnetos give what looks like a feeble spark but are said to be fine in use.

Having said that, a white sparkle doesn't sound that good. Will it burn through a piece of paper?

Re: Boyer Ignition testing and what to expect

Posted by alan_osborn at May 16. 2018

Ian you have not answered the statement by Dan, have you got 12V? Certainly a whitish spark is not much use, needs a decent blue thing. You can send the BB Amplifier back to BB for testing (or to me but BB will give a better test) the cost of a BB amplifier (MKIV) could be £60 while the cost of a decent magneto would be several hundreds, then there is the work fitting it, removal of ignition switch etc.-don't do it. But you do not state the year of the ES2. Is it a dynamo model fitted with electronic ignition (Bad move) or is it an alternator model-plenty of battery charging?

Re: Boyer Ignition testing and what to expect

Posted by ian_soady at May 17. 2018

I wasn't suggesting Dan should fit a BT-H, just using it as a comparison as I had one of these recently and thought the spark looked a bit feeble. I was advised that although it didn't look wonderful it was very effective - although I didn't have the opportunity to try it in practice.

Re: Boyer Ignition testing and what to expect

Posted by tony_ripley at May 18. 2018

Previously jonathan_newton wrote:

I have a BB mk 3 on a ES2 recently purchased which will not start. Valve timing good, compression good, carb and fuel good, battery good on optimate, ignition timing as good as you can set statically, but no sign of starting. It started (after a lot of fiddling) when I bought it and ticked over decently but since then it has been absolutly dormant. 

I read in the boyer documents that if you switch power on/off it should spark at the plug which it does, but not a fat blue   disharge, more of a white sparkle of short duration.  Is that what I should expect? 

If I kick it over with the plug out the the same feeble sparke appears but I am in doubt as to the strength of it to actually ignite the mixture.

I have advanced it further to get at least a miss fire or kick back but no joy. 

 Are there any other tricks or tips I should be looking for before I buy a magneto and be done with it!!!

 Any help appreciated....

Hi,

As mentioned, first check is a good 12V at the Boyer, although you say battery is good on Optimate so that should be OK.

Next, are you happy that you have a good plug / HT lead / suppressor cap / coil ? Can you swap in any known good bits?

Do you have or can you borrow a Gunson colourtune, this will enable you to see inside the combustion chamber as it fires. It is not unknown for a plug to fire out in free air but does not fire when under compression.

Tony

Re: Boyer Ignition testing and what to expect

Posted by jonathan_newton at May 21. 2018

Previously Tony Ripley wrote:

Previously jonathan_newton wrote:

I have a BB mk 3 on a ES2 recently purchased which will not start. Valve timing good, compression good, carb and fuel good, battery good on optimate, ignition timing as good as you can set statically, but no sign of starting. It started (after a lot of fiddling) when I bought it and ticked over decently but since then it has been absolutly dormant. 

I read in the boyer documents that if you switch power on/off it should spark at the plug which it does, but not a fat blue   disharge, more of a white sparkle of short duration.  Is that what I should expect? 

If I kick it over with the plug out the the same feeble sparke appears but I am in doubt as to the strength of it to actually ignite the mixture.

I have advanced it further to get at least a miss fire or kick back but no joy. 

 Are there any other tricks or tips I should be looking for before I buy a magneto and be done with it!!!

 Any help appreciated....

Hi,

As mentioned, first check is a good 12V at the Boyer, although you say battery is good on Optimate so that should be OK.

Next, are you happy that you have a good plug / HT lead / suppressor cap / coil ? Can you swap in any known good bits?

Do you have or can you borrow a Gunson colourtune, this will enable you to see inside the combustion chamber as it fires. It is not unknown for a plug to fire out in free air but does not fire when under compression.

Tony

 Well I must admit that riding became the prefered option for the weekend;  a) for the weather and b) for the lack of  wedding "news".... with  two dead Nortons and one too well stored to break out I opted for the German, push button,  sorry, had to get out.  

 Voltage is good at the BB box, Battery is on optimate and puting out good 12volts, earth side wired direct to battery. New HT (wire type), New cap no suppression, NGK B6ES Plug.  I have a Gunson CT but I havent tried that (good tip).  I think I will return the set up to BB to put my minds at rest.

  When I kick it over the commpresion is not that fantastic but I oiled the bore a little to seal the rings a little better.  Will  update you on results.

Thanks all

Jon

 

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