A65 alternator rotor timing marks and pinking

[GlennA65]

Hi Folks. I have a '71 Oil in frame Lightning which has been a pig to get running right. I think I have nearly sorted it and the problem (I think) was a faulty boyer stator plate. Took me so long to figure that out!

However now that's sorted the bike is pinking a bit on moderate acceleration from mid to low revs. I read articles saying with modern fuels, increase the needle jet size which I have done to .1065. It still pinks a little even though the timing is retarded. The plugs are showing signs of being rich.

I thought I would recheck the timing and have gotten confused about the timing marks on the rotor. There are 2 timing marks opposite each other, one marked "I" or maybe "1" and the other marked 2. The manual states:

"Remove the large inspection cover at the front of the primary chain case, to expose the generator rotor, which is marked with two timing lines (at 180° to each other). The correect one for use with A75 models is marked "2" and is adjacent to the name lucas"

Nowhere does is state which one to use for A65's, would that be I/1? I'm pretty sure when I set it up, I used the crank lock tdc tool and the "2" mark more or less aligned. I presume if they are at 180° it does'nt make a difference with the Boyer as it has a wasted spark? Is the I/1 for the opposite cylinder when you have points?

I'm just wondering if I am timing to the right mark.

Many thanks in advance Glenn

[Peter A]

Hi Glenn,

As it's a 360 degree crank with both pistons rising together, using the wrong timing mark would have the plugs sparking at the bottom of the stroke. I've just rebuilt a 1971 A65FS and timed it to the number 2 timing mark. All is running fine. If you position the crank for tdc using a plunger timing tool through the front lower crankcase aperture into the slot in the flywheel, you will notice that the pointer lines up with the number 2.

Good look
Peter

[GlennA65]

Thanks Peter, this does seem logical. Maybe the A75 reference in the manual is a typo. Wouldn't be the first I've come across. The pinking must be due to some thing else I guess. Weird to get pinking and richness together.

Cheers Glenn

[limeyrob]

Some thoughts (I bought an 71 OIF A65L new..):
Sooty plugs could be from a rich idle but top end could still be lean.  I had high comp pistons (10.5), took the air-filters out and fitted electronic ign and I think I had to go up 2 sizes on the main jets (220?).
These engines run hot, what plugs are you using?
If the timing is too retarded it may soot plugs and overheat, I suggest trying the correct timing first, then adjusting from that.
Take a look at the advance curve, on the Lucas RITA is didn't reach full advance till around 4000 revs so you have to strobe above that.  Not a job to enamour you with the neighbours!

[GlennA65]

Haha!! No my neighbours are kinda used to it but probably not their favourite thing... I do rev it up to 4500 ish. luckily standard exhaust so not stupid loud.
I have a Boyer system on and it was originally timed spot on. I retarded it a bit to see if that got rid of the pinking. The bike has always been kinda sooty no matter what I have done. I do agree though. it might be worth going back to sqaure one and starting again. especially now that I have the Boyer working properly. It is easy to tie yourself in knots with these things. I currently am running softer (hotter) plugs than recommended because I thought the standard cooler plugs were fouling but again, maybe I should go back to standard.

Many thanks for your thoughts
Cheers Glenn

[GlennA65]

Hi again folks, I am still investigating this issue. Firstly - I'm an idiot! when the strobe runs it is timing to the I/1 timing mark not the 2 as mentioned. Told you I was getting confused.
However, following Limey Rob's advice, I thought I would reset the timing from scratch. The alternator rotates anti clockwise being on the left side of the bike. When I strobe the engine -

the timing mark on the alternator - moves anti clockwise from low revs to high revs.

This seems to me to be the wrong way round. Would that not be from very advanced to fully advanced - rather than retarded to full adv?

The bike starts well and runs quite well except for the pinking on moderate acceleration. I tried reversing the black/white and black/yellow connections from the Boyer stator but apart from a couple of backfires I could not start the bike.

I am so confused right now!

Thanks in advance

[limeyrob]

I think you are right about the advance going the wrong way, its giving me a headache! But as the spark advances it will occur earlier, so that against the rotation.  Could the Boyer we wired for the wrong rotation?  See if you can find a video of a bike (any bike)being strobed and see which way it advances.

[GlennA65]

Thanks Rob, yes I found a vid of Paul Henshaw timing an A65 and I'm sure it went the other way.
I'm glad it's not just me who's head is hurting!
If it's wrong though I can't understand how it runs reasonably this way and not at all the other.
I think I might message Boyer. I'll let you know what they say.
Cheers Glenn

[Alan]

https://vintagebikemagazine.com/technical-articles/boyer-trouble-shooting/
Have you seen this article?

Alan

[rhyatt]

i have heard that it is prudent to use a totally separate slave 12v battery to energise the strobe.
prevents it getting spurious spikes from the bike's own charging system

[GlennA65]

i have heard that it is prudent to use a totally separate slave 12v battery to energise the strobe.
prevents it getting spurious spikes from the bike's own charging system

Thanks Rhyatt, yes I'd read that too so I did do that. At least I got something right

[GlennA65]

https://vintagebikemagazine.com/technical-articles/boyer-trouble-shooting/
Have you seen this article?

Alan

Thanks Alan, I had not seen that particular article. Most of the stuff I have already done several hundred times but it does go into territory I have not seen before near the end and that seems to get close to my problem. I only glossed over it today and will need to read that last section more carefully. V interesting. Many thanks, Glenn

[GlennA65]

Actually Alan, the section at the beginning was really good too as it explains the markings on the rotor. Brilliant! Thanks again

[GlennA65]

So I sat myself down with a cup of tea and a tdc tool and took a long logical look at the advance retard problem. Of course it is going the right way . Got myself in a pickle with it. Sorry for bothering you guys with this.
Still got the pinking to figure out. Maybe I'll start a new thread on that after I've tried a few more things. Thanks for your help Folks. Cheers Glenn

[JJC]

On a Boyer, it is possible to have the advance/retard working backwards.  I've managed to do this through my own incompetence.  Many many years ago I fitted one to my OIF A65L and got the black/white and black/yellow wires between box and stator crossed over.  When I got it running and put a strobe on it, it was retarding with increasing rpm.  What came next was an "ingenious" solution.  I removed the rotor magnetics and swapped around their polarity, which fixed the "problem".  Used it like that for a long time.  It worked fine.  Over 30 years later, when I came to upgrade to a digital Boyer,  I then discovered what the real problem was.  As regards pinking, the bike sat unused and unloved for many years and when brought back into service, it had a pinking issue.  Two things had changed to give rise to this.  Firstly, leaded fuel had disappeared from the scene and I also fitted a SRM bigbore kit during recommissioning, which seemed to have significantly higher compression.  It took me a long time to sort the pinking issue but it has been fixed completely.  Went richer on the slides.  Number 2.5 was better than 3 and number 2 better than 2.5 in terms of pinking.  The richer slides made for overly rich running but this was fixed by downsizing the needle jets from 106 to 105.  The pinking, which was very bad, has been completely eliminated and plug colour is fine.  These changes were made years ago and the bike has done several thousand miles since, without any detonation related issues.