The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: BSA500 on 06.09. 2018 21:36

Title: Pinking and issue
Post by: BSA500 on 06.09. 2018 21:36
Hi
 The A7ss is having terrible issues with pinking. Ah just reftme the engine you say but that's the issue. I cannot get the atu off as the extractor bolt keeps slipping.
How do get it off without damaging the magneto and or the pinion
Title: Re: Pinking and issue
Post by: Greybeard on 06.09. 2018 21:44
In case you haven't done it, clean, check and adjust the points. The gap affects the timing. You may not need to do more.
Title: Re: Pinking and issue
Post by: BSA500 on 06.09. 2018 21:57
I will check tomorrow good shout
Title: Re: Pinking and issue
Post by: muskrat on 07.09. 2018 13:34
G'day BSA500.
As GB said.
Pinging can be very destructive if not rectified. (broke the top ring in 3 of the 4 cylinders in my CB1100F)
You'll need to retard the timing or increase the octane of the fuel or richen the mixture.
Cheers
Title: Re: Pinking and issue
Post by: BSA500 on 07.09. 2018 17:41
I tried the highest octane no improvement and the mixture is fine with a little bit of richness. I am feeling regarding the ignition if I can get the pinion off
Title: Re: Pinking and issue
Post by: BSA500 on 08.09. 2018 13:29
Measured the points gap and it's spot on. So how do I get the pinion off when the extractor bolt doesn't  well extract without damaging the magneto
Title: Re: Pinking and issue
Post by: BSA500 on 01.10. 2018 13:10
Just bumping this. Winter is starting to draw in so some suggestions and how to do this to keep me occupied would be appreciated.  *smile*
Title: Re: Pinking and issue
Post by: BigJim on 02.10. 2018 21:26
Am a bear of little brain and this is the first time i have offered advice. Maybe a little heat applied to the centre of advance unit and freezing spray (stuff plumbers use on pipes) on shaft taper. Tapping and levering all at the same time. Assume adv unit will be scrapped so tooth damage irrelevant.  *work* *conf2*
Title: Re: Pinking and issue
Post by: muskrat on 03.10. 2018 09:08
G'day BSA500.
Been a long time since I had this problem (25 years). I think I undid the three nuts holding the mag and used timber wedges between the mag flange and c/case. Then applied heat to the center of the advance unit as BJ suggests, screw the nut on a few threads and tap-----Hit-----BELT the nut.
I don't condone brute force but what has to be done, has to be done.
Cheers
Title: Re: Pinking and issue
Post by: Triton Thrasher on 03.10. 2018 09:56
What is the timing set to now?
Title: Re: Pinking and issue
Post by: wortluck on 04.10. 2018 20:00
Tappets were my issue with pinking - as they were completely fubar  *whistle*
Title: Re: Pinking and issue
Post by: BSA500 on 09.10. 2018 12:34
Timing is set as standard for a A7SS as I have the alloy head. The adv unit fibre cog is new and refurbished so I dont want to destroy it. I am not happy with belting the end of the mag in any circumstance.
Title: Re: Pinking and issue
Post by: coater87 on 09.10. 2018 13:24
Timing is set as standard for a A7SS as I have the alloy head. The adv unit fibre cog is new and refurbished so I dont want to destroy it. I am not happy with belting the end of the mag in any circumstance.

 The fiber gear is the cheapest thing you are dealing with.

 Unless you can figure out a puller, I think your down to tap-tap-tap-a-roo (ala Happy Gilmore).
Title: Re: Pinking and issue
Post by: BSA500 on 26.10. 2018 20:11
Got it off just light offering on the strongest mounting on atu and off she popped. I think it's 3/16 BTDC what should I aim for to retard a little. No wrong 3/8
Title: Re: Pinking and issue
Post by: BigJim on 26.10. 2018 22:32
Great to hear atu removed. Will it need to be replaced? maybe a spare/alternative one is a good idea. Am not able to help with timing (sorry) as have A10 iron head. If able and confident it may be worth looking at easing out the mounting holes for the magneto for easy fine tuning of timing. Lots of info on this forum on how to do that and could mean the atu stays on a bit longer if pinking does not go away. Good luck, keep on keeping on.
 *beer* *good3*
Title: Re: Pinking and issue
Post by: BSA500 on 27.10. 2018 09:27
What is the timing set to now?
I'm not sure now 5/16 keeps popping up in my head but I think 3/8 is the one I read for a a7ss. Confusing me trying to get my head around is 3/8 more retarded than 5/16
Title: Re: Pinking and issue
Post by: muskrat on 27.10. 2018 09:48
G'day BSA500  *yeah* *yeah* *yeah* persistance pays off.
Timing for an A7SS is 3/8" btdc = 38 degrees with the auto unit wedged to max advance.
Mate, I'd be looking for a new nut for the auto unit. And even then use a little vasso on the taper till you get the timing set up just right in practice before you clean and do it for good. It tends to move when tightening so you can guesstamate the movement and incorporate it into the position before tightening the nut.000000
Clear as mud, right?
Cheers
Title: Re: Pinking and issue
Post by: BSA500 on 27.10. 2018 10:08
Quote from: muskrat link=topic=13398.msg111237#msg111237
date=1540630113
G'day BSA500  *yeah* *yeah* *yeah* persistance pays off.
Timing for an A7SS is 3/8" btdc = 38 degrees with the auto unit wedged to max advance.
Mate, I'd be looking for a new nut for the auto unit. And even then use a little vasso on the taper till you get the timing set up just right in practice before you clean and do it for good. It tends to move when tightening so you can guesstamate the movement and incorporate it into the position before tightening the nut.000000
Clear as mud, right?
Cheers
I am pretty good at putting the atu on without moving the armature it's my only talent. I will check the timing tool to see what I last set it to. I perm marked it. I am I right thinking 3/8 is more retarded than 5/16. I may have cocked up last time. Don't know why used 5/16
Title: Re: Pinking and issue
Post by: Black Sheep on 27.10. 2018 10:17
3/8 is more advanced than 5/16. I use 5/16" on my A7. Less likely to pink on 5/16".
Title: Re: Pinking and issue
Post by: Greybeard on 27.10. 2018 10:44
3/8" is 6/16" so larger; more advanced.
Title: Re: Pinking and issue
Post by: BSA500 on 27.10. 2018 11:06
Dammit. So if it was set to 5/16 say what should I aim at to retard a little. I know a degree disc is a good way and I have one I am just not fancying taking the primary case off. I have only just got it leak free.
Title: Re: Pinking and issue
Post by: Swarfcut on 27.10. 2018 11:30
  Don't forget that these piston height figures are a rough translation of the true angle of ignition advance, published back in the day for the average backyard mechanic, working on a stock motor., running on the available fuels of the day. Anything you do to modify from stock will affect the optimum ignition timing. That includes the fuel.

  With the reduction of octane rating and removal of anti knock lead, no wonder we have problems.  I would try things as they are with a swig of octane booster.  Otherwise it is trial and error, setting it retarded and advancing until it just pinks, then retard slightly. That's the best you will get.
 
  Swarfy.
Title: Re: Pinking and issue
Post by: BSA500 on 27.10. 2018 11:34
Not easy then  *smile*
Title: Re: Pinking and issue
Post by: RDfella on 27.10. 2018 13:14
BSA500 - if you've set to 5/16 it should not be pinking. Are you sure the advance unit is jammed at full advance when you're setting the timing?
Title: Re: Pinking and issue
Post by: BSA500 on 27.10. 2018 17:02
Lots of careful checking when I put it back together.  It's a reconned atu and magnetic so careful setting up.
Title: Re: Pinking and issue
Post by: muskrat on 27.10. 2018 20:14
G'day BSA500.
As Swarfy said, any deviation to std of the time will mean differences in ignition timing. Higher compression makes the bang happen quicker so slightly retarded timing is needed, higher octane fuel burns slower so a little more advance is needed.
 Two ways to combat pinging is to retard ignition or pour more fuel in (richen the carb settings). By adding octane boost to a certain extent is like retarding the ignition a tad without touching the timing.
Cheers
Title: Re: Pinking and issue
Post by: BSA_54A10 on 28.10. 2018 12:14
Your magneto fires when the points open .
SO increasing the points gap will cause the points to open earlier thus advancing the spark.
The reverse is also true decreasing the points gap retards the ignition.
Forth the purpose of working out the ideal tuning, you can cheat by changing the points gap.
When you have found the opening that causes the engine to run best, pull the plugs , rotate the engine to give the .002" opening and mark the piston stick.
Remember to do it on both cylinders.
If the two marks are different , use the shortest ( least advance ).
Then reset the points to 0.012" and time the magneto using your measurement stick.

It is very common for the cam to be different left to right  .
There are a lot of articles about stoning the cam to make the cylinders timed the same left to right.

AS others have already mentioned the numbers BSA published are only correct for 1950's fuel.