The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: pdg on 24.11. 2014 21:52

Title: K2F auto A/R to manual A/R conversion
Post by: pdg on 24.11. 2014 21:52
Hi,

Does anyone know if it is possible to convert a K2F with an automatic advance-retard to one with a manual advance-retard. The biggest problem might be in getting hold of the thick plate that houses the cable connection for the lever to adjust the timing  as per the photo shown on http://www.a7a10.net/forum/index.php?topic=1045.0 ....?

Thanks, Peter.

Title: Re: K2F auto A/R to manual A/R conversion
Post by: BSA_54A10 on 25.11. 2014 03:22
No problems with doing it but it is a backwards step particularly with modern fuels which will load up your plugs at every chance it gets.
And if you really want to destroy your engine, you can fit both a manual & auto on the same bike.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: terryg on 25.11. 2014 08:46
Can I suggest you talk to Andrew at Priory Magnetos?  It's likely he will have the manual points housing you will need and can also do the conversion if that's what you would like.

http://www.priorymagnetos.co.uk/ (http://www.priorymagnetos.co.uk/)
Title: Re: K2F auto A/R to manual A/R conversion
Post by: Seabee on 25.11. 2014 13:05
I'm wanting to do this also for my 57 RR.  I bought it with an auto advance mag on it, but I think all the export RR's had a manual advance mag?  I've been collecting parts, but I still need the points guts and a gear nut.  Then I think I have it all.  I have the manual housing and solid driven gear. Musky?

Joe
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 25.11. 2014 17:21
Many thanks to all. I have spoken to Andrew at Priory Magnetos after I thought I'd submitted the post, but I mustn't have been properly connected to my wifi so it appeared later.

Andrew was really helpful and I'll be trying the conversion in some form in the New Year.

Regards, Peter.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: a101960 on 25.11. 2014 18:08
Quote
No problems with doing it but it is a backwards step particularly with modern fuels which will load up your plugs at every chance it gets.
And if you really want to destroy your engine, you can fit both a manual & auto on the same bike.
It is interesting that you should say that. Here is what Hughie Hancox has to say about manual advance and retard magnetos in his book Triumph "Many years ago, when us young chaps at Meriden with our Tiger 100s and their manually - controlled magnetos got fed up moving the lever to slow up the engine on tickover  then advance the engine again when we pulled away, we decided to fit automatic advance and retards". So, it would seem that someone that has an intimate knowledge of post war Triumphs thought that automatic advance and retard was preferable to manual advance and retard. By the way, the method the Meriden men employed was to retain the manual magneto, set the advance and retard lever to full advance and then remove  the fixed pinion and replace with the automatic unit. The ignition was set at 37 degrees B.T.D.C. that is what the triumph men preferred on their own bikes.
John
Title: Re: K2F auto A/R to manual A/R conversion
Post by: BSA_54A10 on 26.11. 2014 01:04
Back in the "old days" when this stuff called petrol was available things were a little different .
You retarded the spark, started the bike, allowed it to warm set it to full advance and forget about timing unless you are on a long slow hill.

However now days with this stuff called "fuel" which is nothing like petrol, unless you are happy to wear out your left thumb or run plugs 4 grades hotter than standard it is a more of a wank item than a benefit to the running of the bike.
I really notice it when riding in groups and we come to either some steep downhill twisties or long sweepers.
The std bikes with aa units wizz strait through, the manual bikes generally either pink, backfire or even load up a plug and loose a cylinder till it clears up a bit further down the road if at all.
Only one rider with a manual ignition seems to have it down pat, but he has ridden the same bike for 55 years having ridden it from new in 1950 so he knows exactly when and by exactly how much to drop the ignition back and when to forget the ignition and go back a gear.
Sitting around Ken it was very interesting watching the left thumb , he was forever tweaking the timing but by now I imagine he does it involuntarily.

Over the thousands of miles I have ridden with the group, Ken is the only riders with manual timing that has not needed to change a plug at some point in time and his bike always runs well. Mind you going up a hill behind him with his throttle wide open and the timing back a few degrees was music to the ears and a treasured BSA memory.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: beezermacc on 26.11. 2014 08:29
I have a 1955 A7SS, a RGS replica (autojumble special) and a Super Rocket (also autojumble special). All three have ATD's and manual A/R. The bikes retain their sporty look for the rivet counters who wander round meetings 'spotting' non-original parts. When riding the bikes I don't think I ever touch the A/R lever apart from on the RGS lookalike because that has high comp pistons and will pink if I'm lazy changing gear up hills. With manual A/R alone you need to retard the lever to prevent the bike kicking back when starting. If you move the lever too far you are at risk of killing the spark so much that it will not ignite the modern fuel (otherwise known as P155). With experience most riders know where to put the lever so that they have enough spark and enough retard to start the bike without  kickback. However, fitting an ATD in addition to manual A/R allows you to start the bike on full advance (i.e full spark) in the knowledge that the ATD has retarded the magneto but not weakened the spark so starting should be a doddle. Retaining the manual A/R allows you to retard the ignition slightly when going uphill if the bike is inclined to pink due to the P155 in the tank.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 26.11. 2014 08:55
Many thanks for the really useful discussion. Would the manual A/R on full advance be able to overcome any drag from a tacho drive attached to the mag, or would it be necessary to over-advance the timing to compensate?
Title: Re: K2F auto A/R to manual A/R conversion
Post by: Triton Thrasher on 26.11. 2014 21:00
Many thanks for the really useful discussion. Would the manual A/R on full advance be able to overcome any drag from a tacho drive attached to the mag, or would it be necessary to over-advance the timing to compensate?

Time as normal.

By the way, don't take  a tacho drive from an auto advance magneto pinion, though.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 26.11. 2014 22:01
I now understand I can't run a tacho off a mag with an ATD. Which model of BSA ran a tacho off a drive like the oil pump or another 'solid' drive that I might be able to copy?
Title: Re: K2F auto A/R to manual A/R conversion
Post by: muskrat on 27.11. 2014 08:49
The drive from the oil pump was used from 1960 models and it has a different inner timing cover with a boss and hole forward of the oil pump. The pump has an extended spindle which fits the cable like the A65 types.
Cheers
Title: Re: K2F auto A/R to manual A/R conversion
Post by: beezermacc on 27.11. 2014 09:05
Following on from Musky's comment above, the inner timing cover from a Super Rocket (or any shortstroke A7/A10) is not interchangeable with a longstroke inner timing cover. Should you wish to drive a tacho on a longstroke you would need to either a) modify your inner timing cover to provide a hollow boss through which the extended oil pump spindle would run or b) modify the outer timing cover to accept a bevel drive gearbox (Road Rocket type) and use a manual A/R magneto.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: WozzA on 27.11. 2014 09:09
Inner cover
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 27.11. 2014 13:02
Looks like I'll be better of keeping the bike standard and not having a tacho!

Many thanks for everyone's help and patience.

Regards, Peter

Title: Re: K2F auto A/R to manual A/R conversion
Post by: terryg on 27.11. 2014 13:16
What about an electronic tacho?  Wasn't there some discussion on here recently, including magneto ignition?  Sorry, too lazy to use the search just now...
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 27.11. 2014 13:20
Yes. The ones I've seen require 12V so it is something I could go for with a change from 6V.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: terryg on 27.11. 2014 13:37
A neat little 6-12V DC-DC converter, tucked in somewhere?
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 27.11. 2014 13:39
Does anyone know if the Gold Star tacho+speedo mounting plate that fits across the handlebar yoke is a standard fit - e.g. is it likely to fit an A7 long stroke or did BSA produce different yokes for different bikes. The item I'm thinking of is shown at http://www.classicbikepartscheshire.com/speedometer-tachometer-c41/speedo-mounting-spares-c42/classic-motorcycle-bsa-speedo-tacho-mounting-bracket-p515 but this has the cut out for the ignition key that clearly I don't have.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: Topdad on 27.11. 2014 13:57
I beleive that all the plunger and swinging arm yokes and forks interchange can't help re the longstroke though but BSA were so mean about changing things I be surprised if it were diferent. The key cutaway is gfor a steering lock not ign key , goldies were mag fitted as well as ours ,regards BobH
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 27.11. 2014 14:26
A neat little 6-12V DC-DC converter, tucked in somewhere?

What a lovely idea - very smart. I'll look into it.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 27.11. 2014 14:46
I beleive that all the plunger and swinging arm yokes and forks interchange can't help re the longstroke though but BSA were so mean about changing things I be surprised if it were diferent. The key cutaway is gfor a steering lock not ign key , goldies were mag fitted as well as ours ,regards BobH

Many thanks. I'll give it a go.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: wilko on 27.11. 2014 23:43
here you go.  http://www.ebay.com.au/itm/221207451815?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Title: Re: K2F auto A/R to manual A/R conversion
Post by: wilko on 27.11. 2014 23:50
And.....http://www.ebay.com.au/itm/1960s-70s-Vintage-BSA-Triumph-Norton-S424-A7-A10-outer-engine-timing-cover-3-/231312737313?pt=Motorcycles_Parts_Accessories&hash=item35db504421
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 28.11. 2014 05:06
Many thanks.
Does the K2F mag send a sacrificial spark to each cylinder (e.g. sparks twice at each cylinder every 4 revolutions) or does it send just one spark to each cylinder every 4 revolutions?

Regards, Peter.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: duTch on 28.11. 2014 10:08

Quote
Does the K2F mag send a sacrificial spark to each cylinder (e.g. sparks twice at each cylinder every 4 revolutions) or does it send just one spark to each cylinder every 4 revolutions?

 Well if you think about it, the cam spins half speed of the crank, and there's only one brass strip in the slip-ring- so that'd have to mean something..?
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 28.11. 2014 12:40
Sounds like both plugs spark every 2 revolutions, meaning a sacrificial spark.  *eek*
Title: Re: K2F auto A/R to manual A/R conversion
Post by: Triton Thrasher on 28.11. 2014 18:15
Sounds like both plugs spark every 2 revolutions, meaning a sacrificial spark.  *eek*

They don't.
Title: Re: K2F auto A/R to manual A/R conversion
Post by: bsa-bill on 28.11. 2014 20:04
Quote
Sounds like both plugs spark every 2 revolutions,

Hi pdg
They do but not together,
each revolution of the magneto produces two sparks, 180degrees apart, in that time the crank has revolved twice completing four strokes in each cylinder who's compression strokes are 180 degrees apart, so no spare spark to be had.
I know the more you think about this one the more the big bang theory makes sense
Title: Re: K2F auto A/R to manual A/R conversion
Post by: pdg on 28.11. 2014 20:32
Quote
Sounds like both plugs spark every 2 revolutions,

Hi pdg
They do but not together,
each revolution of the magneto produces two sparks, 180degrees apart, in that time the crank has revolved twice completing four strokes in each cylinder who's compression strokes are 180 degrees apart, so no spare spark to be had.
I know the more you think about this one the more the big bang theory makes sense

Many thanks for the clarification.
Regards, Peter.