Still Running like a dog!!!

[paulbaker1954]

OK now at wits end completely. New head gasket fitted (OEM), carbs fully overhauled and check of all pilot circuits etc and still running like a dog.

Checked for air leaks around carb rubbers etc

Symptoms are it starts up fine and sounds fine but as engine gets warm I get a afterfire in exhausts 1 and 2 and it will just not pull at all.

Am beginning to wonder if I have an ignition problem. The bike was fitted with a full Boyer kit including micro coils 18 months ago.

Anyway here is my question.

As I understand it the BOyer system fires all four cylinders so if this is correct I should be able to swap plug leads 1 and 2 over to 3 and 4 and vice versa.  If I then get the problem on cylinders 3 and 4 instead of 1 and 2 it points to either a plug cap or lead or other ignition issue.

A further question is if I can just swap over the yellow and blue wires on the Boyer stator plate and will this have the same effect as swapping over the plug leads

[K2-K6]

I see that as the same as you for both questions, it will swap different sections though.

The odd thing is from their strategy it should be cylinders 1 and 2 fired from different high tension supplies, so why would they both give problems unless there's something in their "secret" crossover electronics that is causing a related fault to travel down both routes. Just thinking out loud really there.

I would try both of those diagnosis changes separately to see what effect they generate,  then discuss findings.

[paulbaker1954]

Good point there

the Boyer system is 2 mini coils each with 2 HT outlets so am guessing each coil feeds 2 cylinders rather than there being 4 coils if you see what i mean ie the sam as the Honda original concept

I have also emailed Boyer to ask what other tests they can recommend

[Nurse Julie]

🤔Honda SOHC/4's only have 2 coils, with 2 HT leads coming out of each. I'm I not understanding the question Paul 🙄🙄🙄🙄🙄

[K2-K6]

Yes as above,  the Honda system has one coil supplying cylinders 2 and 3 switched by one set of points,  and the other set doing 1 and 4. It's easy to spot faults as they run completely independently of each other apart from voltage supply from ignition switch,  making fault finding very logical if you work down each discreet line to plugs.

What the later Boyer claims to do is crossover even those two discreet systems so each pickup fires both coils with their internal switching  so difficult to see what is going on.

So plugs one and two would normally have seperate supply integrity,  but now are linked in some way if that makes sense. So a little confusion in trying to diagnose what's happening.

See if you get anything from swap testing that's going to shed any light on it.

[Laverda Dave]

It could be something really simple. Years ago my speedway bike would start easily and then die on the start line as it was revved. I thought it was the magneto and swapped it out but still the same. It turned out to be the spark plug breaking down under compression but only when it got hot. The plug was a NGK and something I didn't expect given their reputation.
Are all your spark plugs new Paul? It might be worth swapping them over to see it the missfire follows them around?

[K2-K6]

Agree Dave, trouble is I forget who's had new plugs or not when these symptoms get more reluctant to be resolved 

If they are not verified it would be good to do so.

What I don't understand is the connection between 1 and 2 as they should be discreet for HT response even if they were triggered by common switching.

[Johnwebley]

the one common item to 1 and 2 is fuel supply,

I run a Boyer,and you can put any plug lead on any plug,and it still runs .


 mine had a similar issue about 5 yrs ago,,I got new plug caps and plugs,

 not sure what cured it,but,touch wood,its OK now

[paulbaker1954]

Yes the Boyer system does not help when it comes to diagnosis, I have emailed Boyer with the symptoms to ask what tests can be done so I will also see what they come back with

What I don't know is how the Boyer Micro coils work as they are digital and current driven as opposed to voltage driven but I do know that the system fires all cylinders at once as opposed to the original Honda set up that fires 1 and 3 and 2 and 4 together (wasted spark).

Looking at the picture of the coil pack it is clearly different to a conventional coil in some way and is sold as a "dual output" device. I am therefore assuming that if there is an issue with it it will be see on the the 2 cylinders it feeds assuming 1 coil feeds 2 cylinders

The wiring diagram Boyer supply shows the coil pack feeding 1 and 4 and the other feeding 2 and 3 but until I can get to the bike I cant remember how I wired the HT leads in. Not sure why they show the wiring like this if all cylinders are fired at the same time anyway.

The other "unknown" is what purpose the yellow and blue feed wires from the stator plate do in the Boyer control box it could be that there is a wiring fault between the stator plate and the Boyer unit.

Anyway seems like I am still on a learning and testing curve but I will post more as things develop hoping that it may be of use to others down the line diagnosing Boyer systems

One useful thing is Boyer will do a full test on any system for £17 and if there is a warranty fault the fee is not charged anyway.

[K2-K6]

I didn't consider that you may have them arranged like that,  1 and 2 supplied from one coil.  In that case if it's installed that way,  then it could be something on that one coil causing you problems.

That'll teach me to assume it's going to be arranged as per Honda layout if that's the case. 

I have distant memories of being schooled in the statement of "assumption is the parent of most f*ck ups" 

Be interesting to see what you've got on there.

[paulbaker1954]

I didn't consider that you may have them arranged like that,  1 and 2 supplied from one coil.  In that case if it's installed that way,  then it could be something on that one coil causing you problems.

That'll teach me to assume it's going to be arranged as per Honda layout if that's the case. 

I have distant memories of being schooled in the statement of "assumption is the parent of most f*ck ups" 

Be interesting to see what you've got on there.

Actually to be pedantic its a Bruce Willis quote from the Die Hard films as in "assumption is the mother of all f*** ups"

[Erny]

Paul,
interesting info about Boyer micro digital ign, they declare power consumption less than stock, I just wonder how this can be if all coils fires at the same time (2x more sparks)?

I was thinking in the last days to buy, but will rather wait a bit - curious to see what will be result of your investigation

[paulbaker1954]

Paul,
interesting info about Boyer micro digital ign, they declare power consumption less than stock, I just wonder how this can be if all coils fires at the same time (2x more sparks)?

I was thinking in the last days to buy, but will rather wait a bit - curious to see what will be result of your investigation

Could be a while - I have very limited Garage time over next few weeks

[K2-K6]

I didn't consider that you may have them arranged like that,  1 and 2 supplied from one coil.  In that case if it's installed that way,  then it could be something on that one coil causing you problems.

That'll teach me to assume it's going to be arranged as per Honda layout if that's the case. 

I have distant memories of being schooled in the statement of "assumption is the parent of most f*ck ups" 

Be interesting to see what you've got on there.

Actually to be pedantic its a Bruce Willis quote from the Die Hard films as in "assumption is the mother of all f*** ups"

We were told that in the late 1970s as apprentice by somebody who tutored us but worked in air accident investigation at Farnborough,  so I'll claim the technical high ground on that one with your kind permission Paul 

Now I've just got to have a word with Mr Willis regarding copyright 

[paulbaker1954]

Can you refit the original points etc, bit of a bugger I know but would confirm where the fault lies.

I could but the old well knackered coils went in the bin a long time ago !!