The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: emilios on 15.01. 2010 16:58

Title: timing wheel?
Post by: emilios on 15.01. 2010 16:58
Hi
Im just wondering where and how to put timing wheel to set ignition timing..
Title: Re: timing wheel?
Post by: MG on 15.01. 2010 18:45
Hello emilios!

You can put the timing disc on either end of the crankshaft and tighten it with a suitable nut.
With everything assembled (oil pump drive, primary cush drive) I have also fitted it to the outer nut of the primary cush drive with simple double-sided adhesive tape. I usually make a pointer out of a piece of wire and tighten it to the engine casings with one of the cover screws.
Title: Re: timing wheel?
Post by: emilios on 15.01. 2010 19:09
thanks MG...
I set ignition timing without head before a week or so....but i forgot to check both cylinder..
So i will check tomorrow but i dont want to take head off...so i will do it with the timing wheel..
I looked around some topics and found out that 3/8 is 35.5 degrees...
Title: Re: timing wheel?
Post by: MG on 15.01. 2010 19:41
With the iron head models I don't use more than 33 deg, otherwise they tend to ping under load.
Title: Re: timing wheel?
Post by: emilios on 15.01. 2010 19:48
Yes but i put hc pistons and thats what the supplier set..3/8
???
Title: Re: timing wheel?
Post by: MG on 15.01. 2010 19:57
Maybe the HC pistons were designed for the alloy head models?
36 deg BTDC would be the timing figure for the Rocket.
Title: Re: timing wheel?
Post by: emilios on 15.01. 2010 20:05
Do you thing that HC pistons will cause any problem to my iron head engine? or if i stay down to 33 deg will be ok?
Title: Re: timing wheel?
Post by: MG on 15.01. 2010 20:07
I'm running the iron head GF on 9:1 without any problems (@33 deg). Just found it tends to ping when advanced further than 33 deg.
Title: Re: timing wheel?
Post by: emilios on 15.01. 2010 20:22
Ok so im going to 33 deg tomorrow morning..
Title: Re: timing wheel?
Post by: emilios on 16.01. 2010 12:30
Today i checked if both cylinders fire the same time...and i found one at almost 34 deg and the other almost  26 deg...
After 2,3 attempts i have both cylinders firing 32 deg...
I didnt run bike far...only half mile or so but i notice much less vibration and much smoother engine...
im planning to do a 50mile trip tomorrow to see how it goes...
Title: Re: timing wheel?
Post by: MG on 16.01. 2010 13:42
Sounds good, congratulations!
32 deg is definitely OK.

Enjoy your trip tomorrow and let us know how it went!

Btw: What was the problem with the misfiring we discussed in the other thread? Faulty pickup?
Title: Re: timing wheel?
Post by: emilios on 16.01. 2010 17:05
I put new pickup and new plug caps...but it should be cap cause when i checked them with an multimeter they showed huge resistor....
Title: Re: timing wheel?
Post by: orabanda on 17.01. 2010 00:24
Running my 51 GF on a dyno showed that 30 BTDC was the best setting
Title: Re: timing wheel?
Post by: Brian on 17.01. 2010 00:48
Do any of you mathematical geniuses happen to know what 30 or 32 degrees is in distance before tdc. I run my A10's on 5/16" BTDC and that seems to be about right, go well and no pinging. Thats with iron heads, maybe the alloy ones would tolerate a touch more advance, maybe not.
Title: Re: timing wheel?
Post by: olev on 17.01. 2010 02:00
Brian, Take a deep breath, get a glass of your coonawarra red and a calculator.

T = L + R X (1 - CosA) -   the square root of ( L squared - ((R X SinA)squared))

where
T = distance BTC in mm
A = timing in degrees
L = conrod length in mm
R = engine stroke in mm divided by 2

You will notice I havent worked out how to do the square root or squared symbols
cheers
Title: Re: timing wheel?
Post by: trevinoz on 17.01. 2010 03:54
5/16" is close enough to 32 degrees.
Trev.
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 15:28
Well.. today i thought i was going that trip with my A10...but it just didnt happen..
It took me some time to start and when it start it didnt sound well...like was not firing all the time...
So im going for a mag rebuilt to solve all my problems with firing..
Do you have any idea how to check if my mag needs rebuilt??
Title: Re: timing wheel?
Post by: MG on 17.01. 2010 15:36
If you can preclude faulty pickups, cables, plug caps or plugs, then the problem has to be the amgneto itself.
As it occurs when its cold already, I could imagine faulty windings, slipring or earthing brush. Maybe the contact breaker is faulty? Could also be an out-of round armature.

If you don't know anyone to rebuild your magneto in Cyprus, I might help you out. If you are interested, drop me an email.
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 15:41
Pickup are new...caps too,wire are perfect and points look good(i bougth points last year...
We have a british bike specialist here in Cyprus...(english) he came 6 years ago and he is perfect so better to go there for a rebuilt..
Thanks anyway
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 15:43
Also today i took off the points plate and found that it has a brush behind...it wasnt looking in good condition...i dont know if that could cause the problem..
Title: Re: timing wheel?
Post by: MG on 17.01. 2010 15:54
There is a brush behind the points plate? What mageto do you have on your bike? The standard Lucas K2f doesn't have one.

Can you post a pic of that brush and where it is located?
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 16:08
The mark point is a bolt coming the other way...i dont know if it should be that much length.
Title: Re: timing wheel?
Post by: MG on 17.01. 2010 16:32
emilios

Please have a look at the front side of the mag. There shold be a hollow screw with the earthing brush on top. The brush behind the points plate is used for mags that don't have that to connect the mag body to armature ground.
Somehow I have the feeling that this plate does not belong in this mag. Or am I conmpletely wrong here?
I can't remember having ssen such a plate in a K2F ever.

If you don't have another earthing brush (because its no K2F mag), the one in the points plate might well be the reason for your problems. If the earthing connection is not good, it'll miss sparks.
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 16:36
I do have an earth brush in front of mag
Title: Re: timing wheel?
Post by: a10gf on 17.01. 2010 16:36
picture1, needs to be just long enough to act as stop for the camring movement.
picture2, quite special, brush should not be there. Could be a quickfix because of some problem with the earthbrush connection at the drive side of the mag.

Looks like all parts of your mag needs to be checked thoroughly.
Title: Re: timing wheel?
Post by: MG on 17.01. 2010 16:40
Thanks a10gf for confirming, I was doubting myself for a moment. Has been a while since I've redone the last K2F.

emilios - better have that mag checked over and rebuilt with SUITABLE parts, otherwise your problems will become a never ending story.
Title: Re: timing wheel?
Post by: emilios on 17.01. 2010 17:25
I will certainly go for a rebuilt to spacialist...
Title: Re: timing wheel?
Post by: LJ. on 17.01. 2010 19:40
Emilios... The top picture showing the inside of the points housing does look rather dirty/greasy, It is important that the back is very clean for the carbon brush to make good electrical contact. The brass points plate is correct and does have this carbon brush on the back, my red A10 also has this type of plate. Some A10's have the steel contacts plate which from what I understand is supposed to be better because it does not wear away like the brass ones sometimes do. They are both interchangeable but the centre bolt is different. Clean the carbon brush and gently pull on the spring to allow a better pressure, but if carbon is too worn then a new one is needed. Make sure the earthing screw at the other end of magneto is clean and making good contact also.

Even if the windings and condenser is in need of replacing, you should still be able to start bike when cold. A poor magneto is usually noticed when it is hot as you cant get it started again until the magneto has cooled down. I would spend a little more time on cleaning and setting up before sending magneto away.

Edit: Just reading back over the whole thread... Do not make the mistake of fitting resister type plug caps or resistor High Tension cable. I was a little unsure if you had made that mistake...

Quote
I put new pickup and new plug caps...but it should be cap cause when i checked them with an multimeter they showed huge resistor....
Title: Re: timing wheel?
Post by: MG on 17.01. 2010 20:54
I've seen such plates in Bosch and ML mags, but these don't have another earthing brush. Doesn't make sense to me, the earthing connection is made by the brush at the front of the mag and to the points plate by the tapered shaft, so what's that additional brush for? Even if it has bad contact, this shouldn't have any effect on the mag, unless the other brush is worn, too.  ????

Anyone got a clue?
Title: Re: timing wheel?
Post by: a10gf on 17.01. 2010 21:18
Ahh... a mystery! 2 different versions of the brass points plate! I've seen a few k2f brass plates, but none with any brush. For different mag bodies or what?
Title: Re: timing wheel?
Post by: orabanda on 17.01. 2010 22:34
Some of my A10 mags have the carbon brush in the back of the brass plate, some don't.
Title: Re: timing wheel?
Post by: MG on 18.01. 2010 06:54
Hm, funny. Maybe there had been a version without the front earthing brush available at some time? That would be the only reason making sense to me. Might also have been an "universal" points plate for different mags, one without any other earthing brush.
Where is Joseph Lucas when you need him...?
Title: Re: timing wheel?
Post by: LJ. on 18.01. 2010 09:53
Joe and his 'dark' secrets eh?  ;)
Title: Re: timing wheel?
Post by: muskrat on 18.01. 2010 12:03
If he is where a lot of riders wished him over the years it would be very hot.
Title: Re: timing wheel?
Post by: MG on 18.01. 2010 12:05
Quote
If he is where a lot of riders wished him over the years it would be very hot.

...and dark
Title: Re: timing wheel?
Post by: LJ. on 18.01. 2010 14:12
... But someone else says... "Let there be light"! and there was light, and everything was good. If only it was 'that' easy Joe.  *lol*
Title: Re: timing wheel?
Post by: MG on 18.01. 2010 14:34
Did you guys know that Lucas built vacuum cleaners once? It was their only product that did NOT suck.
Title: Re: timing wheel?
Post by: groily on 18.01. 2010 17:47
I think we're too hard on Uncle Joe sometimes. He made his stuff to suit the tightwads at the factories - they could have had better quality and better longevity, but I reckon they didn't think we were worth it. In light of that, Uncle Joe's magnetos do work pretty well, or I think they do anyway. Even our under-sized over-stressed little dynamos aren't all bad, although I don't think much of the regulators myself.

I don't know why some brass cb backplates have the brush fitting either - just that some of them do. Never seen a K2F without the standard earth brush either.

As a lot of folk here have said a few times, the first thing to do with any newly-acquired beast of unknown provenance is to get the mag rewound, sort the charging out from end to end, and you're half way to having a reliable bike. I've no idea what the stats are, but I bet well over half of all classic breakdowns bar punctures are down to optimism winning out over prudence in the electrical department. (I know mine have been!)
Title: Re: timing wheel?
Post by: MG on 18.01. 2010 17:58
groily - absolutely agree. We have to bear in mid that these things are 50+ years old. I want to see today's motor control unit or microprocessor-ignition-module in 50 years. Well, maybe I even will...
Title: Re: timing wheel?
Post by: trevinoz on 18.01. 2010 21:42
If you have a look at the Lucas parts book, all brass point plates have an earthing brush and spring.
It must have been unnecessary as it was dropped when the steel plates were introduced.
If my points don't have a brush, I don't worry about it and fit them anyway.
As already stated, the brush plate makes contact with earth through the shaft.
Trev.
Title: Re: timing wheel?
Post by: olev on 18.01. 2010 22:29
Did you guys know that Lucas built the first English fridges?
and thats why they drink warm beer.
Title: Re: timing wheel?
Post by: emilios on 19.01. 2010 17:58
If you have a look at the Lucas parts book, all brass point plates have an earthing brush and spring.
It must have been unnecessary as it was dropped when the steel plates were introduced.
If my points don't have a brush, I don't worry about it and fit them anyway.
As already stated, the brush plate makes contact with earth through the shaft.
Trev.
But if brass point plate makes contact with earth through the shaft...what for is spring with brush there??
It doesnt make any sense to me.
Title: Re: timing wheel?
Post by: a10gf on 19.01. 2010 18:21
Quote
all brass point plates have an earthing brush and spring
nope!
Am also interested in the answer to the riddle (why some with and some without?)