A65 alternator rotor timing marks and pinking

[GlennA65]

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

[limeyrob]

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? 

[GlennA65]

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

[scifi]

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.

[JJC]

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.

[DAVE BRADY]

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.

[limeyrob]

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.

[JJC]

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.

[JJC]

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. 

[DAVE BRADY]

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.

[rhyatt]

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

[Ian]

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
 

[GlennA65]

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

[JJC]

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.