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
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
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
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!
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
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
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.
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
https://vintagebikemagazine.com/technical-articles/boyer-trouble-shooting/
Have you seen this article?
Alan
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
Quote from: rhyatt on 27 Apr, 2026, 17:11 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 ::)
Quote from: Alan on 27 Apr, 2026, 08:03 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
Actually Alan, the section at the beginning was really good too as it explains the markings on the rotor. Brilliant! Thanks again
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
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.
Thanks for this JJC.
I'm pretty sure the Boyer is wired up right and the new stator plate seems to have sorted that out plus I have now established it is all turning the right way at least.
Vis a vis the pinking I tried a larger needle jet which seemed to help a little but the plugs are fouling badly. After a compression test I am convinced that the rings have not bedded in. The head is now off and there was terrible oily carbon (the bike has only done 1500mls since rebuild). I think that might be causing the pinking but either way I need the barrels off to sort the oiling before I go any further with carburation. I'm pretty sure it's not the valve guides, they seem well in spec.
Your Jetting info may well be very helpful when i get to that stage so many thanks for that.
Cheers Glenn
I'm on a similar journey with my A10. What rings did you fit and what are you going to fit this time? Also what are your pans for bedding them in?
Hey Limey. I put Gandini Rings in before because they are great in my Triumph. I fitted JP pistons but was advised not to use the rings supplied as they don't bed in easily either. I'm not sure what to fit this time. I just bought a ball hone so maybe I'll give that a go but the barrels had been rebored and honed before. I guess I'll pull the barrels off and see what it all looks like and then have a think. Don't be surprised if you see a new thread asking which rings to fit! I'll report what I find and what I decide to do.
Cheers Glenn
The cause of the Pinking should be found. It's not likely connected to the ignition, gut some weakness of the fuel air mixture.
I had a small Honda that pinked when pulling out into traffic. I solved that by modifying the carb slide to have 1mm less cut-away. Also I then ran on the highest octane petrol available...It solved the slight problem.
Quote from: scifi on 24 May, 2026, 10:51 The cause of the Pinking should be found. It's not likely connected to the ignition, gut some weakness of the fuel air mixture.
I had a small Honda that pinked when pulling out into traffic. I solved that by modifying the carb slide to have 1mm less cut-away. Also I then ran on the highest octane petrol available...It solved the slight problem.
Sounds like the same problem as on my A65L and the same solution. My pinking issue was when accelerating such as coming out of low speed corners just as the throttle was opened. It was lean under these conditions even when the plug colour was saying rich due to worn needle jets. Richer slides and leaner needle jets cleared up everything.
Hi,
What gear are you in when pulling out of slow corners? `Labouring the engine can cause a pinking sound.
So, not quite enough revs and the throttle open a bit too much.
Dave.
Since we don't have accelerator pumps for pick up the mixture can go weak on a sudden throttle opening especially if the needle jet and main are correct. I think it pays to be a bit rich on the throttle cut-away and idle circuit.
Quote from: DAVE BRADY on 24 May, 2026, 12:44 Hi,
What gear are you in when pulling out of slow corners? `Labouring the engine can cause a pinking sound.
So, not quite enough revs and the throttle open a bit too much.
Dave.
Answer: What should be the most suitable gear if there wasn't a pinking issue.
Quote from: limeyrob on 24 May, 2026, 15:20 Since we don't have accelerator pumps for pick up the mixture can go weak on a sudden throttle opening especially if the needle jet and main are correct. I think it pays to be a bit rich on the throttle cut-away and idle circuit.
As well as accelerator pumps, cars used to have vacuum advance systems working alongside centrifugal systems. Opening the throttle to accelerate would reduce the vacuum inlet and the ignition would retard.
Hi,
A656s like to rev a bit. They will go along quite happily in top gear at 30mph but will not anything but the most gentle acceleration. As a general rule I use 1st up to 10mph, 2nd up to 20 mph, 3rd up to 30mph with top from there. These are minimum figures and if there is any load or gradient then add to this. For instance if loaded up with camping gear, two up or on a gradient then hold each gear for longer. For harder acceleration I will probably double the above figures. The gear ratios on the A65 are not as flexible as the A10 as 1st and 2nd are OK but there is quite a gap to 3rd and 4th is quite close to 3rd.
Dave.
sometimes mechanical empathy for an engine that "needs help" cannot be quantified.
if you are pulling at low rpm then open the throttle more gently to allow the engine to follow the twistgrip (if you get my meaning)
my Bantam going up hills , may just get up in 2nd , but is WAY more happy buzzing gently in 1st.
I just sit back with a gentle throttle in 1st - enjoy the scenery at 10mph and the bike will soon tell me when it is happy to accept 2nd gear
I don't know if anyone has mentioned checking the timing mark on the rotor, but I had the same problem for years until I checked the marks with the timing plug and found the rotor was way out, scribed a new mark been fine ever since
Thanks for all the comments on revs. I don't think I slog my engines, I definitely prefer them to spin a bit. Agreed, the gears are a bit funny on the A65. big gap between 2nd and 3rd not much difference between 3rd and 4th. I can make doing a steady 20mph in urban areas uncomfortable but I've given up trying to do it in 3rd, just let it spin a bit. The pinking is most noticeable when pushing it quite hard and spinning it up in 3rd 3000rpm+
Great idea to check the timing marks, I'll try that!
Thanks for all your comments, Cheers Glenn
I forgot to mention the other thing I used to do when mine had a bad pinking problem. I used Castrol Valvemaster and/or Valvemaster Plus. It makes a big difference to pinking/detonation issues. I also tried Tetraboost, which is lead additive. Again it made an improvement. Also, I used to live in Essex and long after leaded fuel had ceased to be, there was a garage in Braintree selling it for classic vehicles. It wasn't cheap and I only tried it once. I still have Valvemaster but I never use it these days since going richer on the slides and leaner on the pilot jet.