Villiers F12 Sloper - no spark...!

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Mowermad
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Villiers F12 Sloper - no spark...!

Hello again!  So the Marquis 4 restoration really is getting to the final stages - only the clutch to fit and the engine to mount.  However, having had the AMAL carb in bits and all washer/gaskets replaced, I tried the first pull on the cord today but ......  no spark.  Can anyone share the procedures to go through to check if the solenoid is faulty or set incorrectly.  I haven't tampered with it or changed anything since dismantling the mower.  I had hoped this would be functional.  Clearly it isn't.

Thanks......

wristpin
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Solenoid ? May be the coil ?

Solenoid ? May be the coil ? Unless you have removed the stator ,the plate that carries the coil , contact breaker points and the condenser, there is nothing to set other than the contact breaker points gap. If you did remove the stator and have not returned it to the original position you will have upset the ignition timing but will usually still have a spark but at the wrong time. Has your machine got an ignition switch mounted in the cowling to the left of the recoil starter. Those switches have been known to play up. 

Did the engine run before you embarked on the overhaul?

robint
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put a multimeter across the

put a multimeter across the points switch, must use my 515 as a test bed and show smart things to do with a multi meter

hortimech
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I think he means condenser,

I think he means condenser, though it is probably just that the ignition points want cleaning and resetting.

You also cannot test a coil or condenser with a multi-meter, you need a special test machine for this.

Mowermad
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Hmmm.  Thanks guys.  Well, I

Hmmm.  Thanks guys.  Well, I probably do mean coil.  There is no switch on this machine - I think this was more prevalent on the Mk 4 A wasn't it..??  No - the engine was seized when I got it so I have had to release the cylinder and clean up the valves etc. I'm not sure where to start with checking the points and coil to see if it is generating sufficient voltage to create the spark.  Even if the timing was out, it should create a spark at one point in the cycle shouldn't it...?

 

robint
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There are some nifty things

There are some nifty things you can do with an analog multi meter ie one with a dial needle.  I'll have to get my test bed going then i'l post some results.  But this only applies to the simple coil and points job not the electronic version which I havent fiddled with yet.  Its meant to be a winter thing

robint
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Some mower suggested

Some mower suggested

 

get one of these

https://www.ebay.co.uk/itm/Sparkrite-Inline-Spark-Plug-Tester-HT-Lead-Ig...

invaluable

shows up sparks you wouldnt see in bright light clearly

 no mower should be without one - like a leccy without a neon screwdriver - yes i know what elf and safety says

Mowermad
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Thanks Robint - I'll get to

Thanks Robint - I'll get to work as suggested..any other suggestions will be gratefully received.

wristpin
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I think he means condenser,

I think he means condenser, though it is probably just that the ignition points want cleaning and resetting.

You also cannot test a coil or condenser with a multi-meter, you need a special test machine for this.

As has been alluded to above, dirty and out of adjustment contact breaker points are the main cause of ignition failure. . The first step in "finding a spark " is CLEAN points, and by CLEAN,I mean really CLEAN. 

For those new to points ignition systems, this is my way of ensuring that an existing set of points will be as good as possible.  

For a start remove the points from the stator plate. Then, if the design of the points allows, separate the moving and fixed points . Examination of the contact faces may reveal a pit on one and a matching protrusion (T*t) on the other. The objective is to remove both these defects - either with a dedicated points file (difficult to find these days) or a small carborundum slip stone. (yes, I know that it has been written that there is a danger of removing the hard coating of the contacts - possible but unlikely) . The important thing is to keep the contact faces square to one another  and not wedge shaped with a tiny contact patch and day light showing though most of the contact (non contact! ) patch. Reassemble the points and check for that. and adjust accordingly.

Refit the points making sure that any insulating washers etc are correctly positioned and then SET the GAP. - .( On many Villiers engines this is 18 thousandths of an inch). -  With the heal of the points on the high point of the high point of the cam ring using the appropriate feeler gauge. I suggest removing the gauge from the pack  so that you don't have the weight of 30 other ones swinging around making accurate setting impossible..

CLEAN the feeler and insert it between the points and adjust them so that they only JUST grip it  - holding it in place but allowing it to swing under its own weight - not held rigid. When satisfied with the setting cut a strip of "visiting card", apply a drop of contact cleaner, brake cleaner or even petrol, insert it between the points and pull it gently between them BUT DON'T PULL IT RIGHT OUT SO THAT THEY SNAP SHUT AND TRAP FIBRES BETWEEN THEM - open the points a fraction to release it . Then do the same again with dry card.  

That's my way of doing it and on the whole it's reliable. There are other ways and some may suggest looser of tighter gaps etc my my way worked for me for more years than I care to admit too!

Coil and condenser (capacitor) testing.  The easy one first - CONDENSERS.  For a reliable test it is necessary to have a dedicated tester or a meter with a dedicated condenser test function. Attempting it with a general purpose digital multimeter can destroy the meter. What one is testing for is the ability of the condenser to accept a charge and to hold it for a specified time without self discharging.  NON PC , HSE WORKSHOP PRANK , leave a charged condenser lying about and wait for someone to pick it up and get a "belt".  Condensers gradually loose their capacity to perform correctly due to age so in the absence of access to a proper tester it may be wise to replace an old one.

COILS. I tread carefully here as I'm no fan of resistance readings and comparisons with supposed correct  specifications . I've seen many perfectly good coils discarded due to failure to match such specs that when tested on a "real life" tester have proved to be fine on an engine rather than against a book spec.  

Neon spark testers. If that's what you find easiest - fine, but holding the HT lead quarter of an inch from the block has always worked for me!

 

Chris G
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I read this thinking all very

I read this thinking all very good info until I got to this bit..

"COILS. I tread carefully here as I'm no fan of resistance readings and comparisons with supposed correct  specifications . I've seen many perfectly good coils discarded due to failure to match such specs that when tested on a "real life" tester have proved to be fine on an engine rather than against a book spec"

Thinking .... surely you would get an indication from a meter reading, especially a denoted one.

I won't post my outcome here as its electronic not points and not useful to this poster.

However what I have read from a reliable book is the main cause of coil failure is resistance in delivery of the voltage to the plug - i.e. the HT lead, cap or plug itself being faulty/broken down  which makes the coil work a lot harder - basically generating a lot more voltage from the coil.

wristpin
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However what I have read from

However what I have read from a reliable book is the main cause of coil failure is resistance in delivery of the voltage to the plug - i.e. the HT lead, cap or plug itself being faulty/broken down  which makes the coil work a lot harder - basically generating a lot more voltage from the coil.

That's why when testing mags, particularly platform ones, the gap should not be over done . If it is the voltage generated may burn out a perfectly good coil!

 

robint
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Its all going off a bit half

Its all going off a bit half cocked here. I taught electrical workshop practice for a while in a Tech College to day release apprentices (shades of Wilt here) and none of the noises made here sound reassuring to someone skilled in the arts.  Plausible conjecture doesnt cut it in the real world - hence my reason for wanting to look more closely at how magnetos really work.  Mowers are just guessing.  HT Coils can fail their insulation from being overstressed.  No one talks of a Megger test (except me).  This meter puts ca 500vac onto the coil to test insulation between the spark end and the stator end with the coil earth uncoupled from the stator ie just hanging in the air.  If <10Meg then insulation is failing.  Increasing the spark gap from say 0.020" to 0.040" potentially increases the induced voltage from ca 10kV to 20 kV

.  Just holding the ht lead away from the cylinder by say 1/4" is WRONG thinking and may damage coil insulation.  The lead resistance is unlikely to be the cause (its only ca 5K) cw 100k for a hot spark plug

There arent any domestic multimeters that could measure 20kV which is why its not done, there may be some garage test kit which Ive not seen.

The cheapo digital multi meters are ca £2.50, good value for money. I bought half dozen and 4 worked ok rest were binned.

You need to understand that the AVO meter I have (electricians Ford Truck) essentially takes a small amount of current ca 50uA when it is measuring any voltage full scale and the minimum volt is 3Vdc..  so the meters  sensitivity is 20 kohms/V.  the cheap digital is ca 125 kohms/V but we can only measure down to 2mV not 50uV

 

lookiing at this I realise this has probably sent you to sleep and I havent even started on Ohms Law and you need to understand fractions

I thought when I had done some real tests then you would have real figures for comparison rather than guess work.  For example the primary of the HT coil only has a resistance of ca 1 ohm.  This is very difficult to measure in practice, surface contact resistance plays havoc.  if you can get a firm steady contact across the points then see how the reading changes between 1 ohm and o/c and note how you dont always get the same low value and how putting pressure on the points also can change things - hence the need for good clean points.  The secondary has ca 5k ohms

Now electrically speaking I wouldnt rely on that source, its misleading. The main failure is internal insulation breaking down in the coil. They dont burn out through excess current. The size of the points gap has no effect on induced voltage only timing, playing around with the spark gap to get a fat spark is definitely not good.  In day time I couldnt see the plug spark anyway

 

get a couple of cheap digital meters and a £10 analog one (so you can see a noisy signal)  The rule of thumb was that you never brought your prize AVO model 8 to a car electrics too easy to blow it up. use a cheap chinky one.

hortimech
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Multi-meters are okay for

Multi-meters are okay for what they were designed for and it wasn't testing lawn mower ignition coils.

Bragging about being a tutor doesn't cut much ice with me. I served my time as a lawnmower mechanic and when the local agg college came out of council control, they ran a city & guilds course. All the local dealers allowed their workshop staff to attend, for the college this was the class from hell, we knew more than any of the tutors, this wasn't hard though, they knew nothing, one guy spent one night a week for six weeks telling us about synchromesh gearboxes and was very surprised when we asked 'when are we going to do crash boxes ?' (there wasn't any machines with syncro boxes at that time), he also tried to convince us that Greens triple mowers should have narrow tyres because they wouldn't mark as much.

Mowermad
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Well, Gents, it looks like my

Well, Gents, it looks like my lack of spark has created a spark....!  In my eyes you are all highly skilled and very knowledgable and the posts above probably well beyond my technical expertise.  HOWEVER...!  I am pleased to declare that we have some progress if not final success.

Wristpin - I followed your instructions re the points and am pleased to report that we now have a very strong spark on the plug!!  That said, the engine hasn't even murmured any life!  It doesn't look like there is an awful lot of petrol in the chamber so I'm wondering why this might be.  Are there any parts of the carb that need adjusting perhaps?  Also, even with a manual squirt of petrol, nothing seems to be burning.  I feel so near yet so far...  Any ideas?

My thanks as always.

 

robint
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I hardly think that my short

I hardly think that my short time serving as a lecturer in electricity to welders 1 and fitters 2 constituted bragging but it did show me how a little knowledge is a dangerous thing and spraying buzz words to impress those skilled in the arts only shows you up as an bragging ignoramous.  I had a lot of fun teaching these feisty apprentii a thing or two such that they started listening properly while I described how to build an electric chair - half my course was taken up with issues about electrical safety and the other was teaching them the much neglected skill of vulgar fractions and showing just how useful they could be.

I showed them for example how you could get a shock from a 12v car battery - I discovered this down the yacht club in Shoreham.  Winching my boat onshore onto my trailer I was getting a belt of the boat's battery.  I discovered my feet were in sea water, everything was wet and my knuckle test did indeed give me a good tingle.  This doesnt happen on dry land.  For example rain falling from the sky has high resistance

However farm yard animals, horses in field etc are particularly susceptible  and even 12vdc is lethal across a farmyard

 

Some figures

Type of Water Approximate resistivity in Ohms (Ω)
Pure Water 20,000,000
Distilled Water 500,000
Rain Water 20,000
Tap Water 1,000 – 5,000 Ω
Brackish river water 200
Coastal seawater 30
Open seawater 20 – 25

The figures represent a aquaread meter with a cell pvc ca 1/4" ID and 4" long

Try out your own experiments with a multi meter.  Remember that you must dip the probes in quick as you can get a steady reading because , being dc  it will immediately set up an electrolysis on the surface which raises the reading artificially

try it with fresh rainwater, tap water, boiled kettle water (cooled to 25C), distilled water,  DI water , sea water, ice

If you want to get adventurous, find areas on you body that are most sensitive to tingle, learn the knuckle test

Never try any test that involves grasping one contact with one hand and another with the other - WHY?  You tell me and why electricians look cool with one hand in their pockets.

Why are neon screw drivers frowned upon?

What is the combined resistance of a 2 ohm and a 3 ohm  resistor connected in parallel

wristpin
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Try peeing on an electric

Try peeing on an electric fence!

wristpin
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Just holding the ht lead away

Just holding the ht lead away from the cylinder by say 1/4" is WRONG thinking and may damage coil insulation.  The lead resistance is unlikely to be the cause (its only ca 5K) cw 100k for a hot spark p

So you know better that the world's largest manufacturer of single cylinder flywheel magneto engines who recommend that method.

Now electrically speaking I wouldnt rely on that source, its misleading. The main failure is internal insulation breaking down in the coil. They dont burn out through excess current. The size of the points gap has no effect on induced voltage only timing, playing around with the spark gap to get a fat spark is definitely not good.  In day time I couldnt see the plug spark anyway

It was not said that the size of the contact breaker points gap caused problems. What was said that it was unwise to test a platform mag by making the spark jump too big a gap. I suggest that you consult the standard work on Wico mags Edited by Peter Chadbund

 

Antbr123
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While I fully recognise that

While I fully recognise that due to my lack of experience I am not adding anything to this thread, I would observe this thread certainly holds its own on entertainment value!  The comment from Wristpin was priceless and had me rolling around on the floor laughing.  Sparks may be flying - but hey - we are getting closer to bloody fireworks night!

For me - I am all for heated debate as something always results from throwing ideas around,  but I do recognise MowerMads predicament and look forward to a reasoned analysis of his problem and the development of a solution - especially if it involves banter along the way. Meanwhile, I for one am going to keep reading, if only to pick up nuggets of information and an insight to contributors humour. Keep at it guys!

Antbr123 (Tony)
Consider grass in terms of how you would like to be treated yourself - and you won't go wrong!

robint
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As yes Old Chadders seems to

As yes Old Chadders seems to have got himself a bad reputation for bigotry on the
Stationary Engine forum.  doesnt seem to recognise the glaring error of 1.8uF vs 0.18uF for a condenser and when the typo was pointed out just continued to bluster.  Rabbits on about it being a resonant circuit but doesnt say why this is relevant. Wipac foremost manufacturer of magnetos must know what they are doing - yada yada Where have I heard that before? He's off my Xmas card list

I must set up my own test bed, cant stand all this specious conjecture from tree toppers who collect buzz words - too technically illiterate to recognise how ignorant they are

My ripost will always be "and your evidence is............."

robint
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is the timing correct?

is the timing correct?

hortimech
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To robint, from my experience

To robint, from my experience, the sheer fact that you were a lecturer in anything, means you know little or nothing about anything. There is an old saying, those that can, do, those that cannot, teach. From my experience, this is very true. I started work as an apprentice lawnmower mechanic in 1973, I later obtained my Parks & Gardens city & guilds, I spent over 40 years in the trade and only retired early through injury, so do not come on here and try to put me down as not knowing anything, I have forgotten more than you will ever know. I believe that Wrispin has a similar pedigree.

 

robint
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You mastered in bigotry then?

You mastered in bigotry then?

what I said from the outset is that you guys have no proper grounding in electrical matters and so shouldnt try and bluff your way round it.  Stick to what you know or you make a fool of yourself

Note I said up front that I dont understand enough about magnetos and need to set up my own test bench.  Not one of you has thought about the value of inductance mH seen in the primary coil, so I cant yet check this with the ringing seen in the primary tank circuit scope trace but I will get there

I wont subscribe to low level unsubstantiated opinionation.  I am happy to exchange information with enlightend board members - send me pm

hortimech
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[quote]You mastered in

[quote]You mastered in bigotry then?[/quote]

No, but you seem to have mastered Bulls**t

[quote]what I said from the outset is that you guys have no proper grounding in electrical matters and so shouldnt try and bluff your way round it.  Stick to what you know or you make a fool of yourself[/quote]

Sorry to upset you, but, from the point of lawnmowers, I am fully trained in electrics. What I know is lawnmowers, small and very big, so it you that is making a fool of yourself.

[quoteNote I said up front that I dont understand enough about magnetos and need to set up my own test bench. [/quote]

You don't know enough to even know how to to do this.

[quote]Not one of you has thought about the value of inductance mH seen in the primary coil, so I cant yet check this with the ringing seen in the primary tank circuit scope trace but I will get there[/quote

Never seen anybody use an oscilloscope to test a coil, not even sure it will work.

[quote]I wont subscribe to low level unsubstantiated opinionation.  I am happy to exchange information with enlightend board members - send me pm[/quote]

When it comes to lawnmowers, I know what I am talking about (or I will say so), do you ?

[quote]Always look on the bright side of life and don't expect your mower to be a walk in the park[/quote]

You don't know enough to know that if you are mowing a park, you would be riding on something.

Now do us all a favour and go away

 

 

robint
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I have never once claimed any

I have never once claimed any special expertise on mowing machines.  You consistently ignore the points I am making, its obviously over your head and you cant teach old dogs new tricks. I certainly wont waste my time trying to correct your technical errors on electrical . Carry on in blissful self taught ignorance just dont try and poison other humble mowers with narrow minded bigotry. 

You are consistently rude and working against the interests of this club and its new members wishing to listen, learn, exchange opinions, and share information

hortimech
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You claim expertise at every

You claim expertise at every turn and make points that have nothing to do with lawnmowers. Your points do not go over my head, I just ignore them because they have nothing to do with lawnmowers. I also do not understand what technical errors you refer to, I haven't made any, unlike yourself.

I would rather be blissfully self ignorant than be a big head like you, I am also not a bigot.

I am not rude, but I do not suffer fools gladly, you fall into the latter class. You seem to 'spam' this forum with gay abandon, you seem to have a (mostly wrong) opinion on anything and everything. I know I do not know everything, you seem to be totally unaware that you know nothing.

When two people, with a combined working life of nearly 90 years, tell you something will not work, you know better.

I repeat, please go away before you kill this forum, go bother someone else.

Does this forum not have a moderator ? I can assure you that if this user was posting on the mailing list I moderate, he would have been banned quite some time ago.

 

olcadmin
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Folks, I think we need to

Folks, I think we need to turn it down a notch.

A forum like this is not the place for personal attacks and I won't tolerate it. When I formed the club all those years ago there was one simple aim - to encourage enthusiasts with a common interest to share their knowledge and to broaden the appeal of mower collecting. It should be a friendly place.

The forums have been running for around eight years and I have never seen the need to introduce any form of moderation. It's not difficult to add but it really shouldn't be necessary. It would be rather time-consuming for whoever was going to do it and would create delays. On top of this would be the sometimes difficult judgments about relevance of content and the way points are being made.

We have a number of long-standing and very diligent contributors who have over many years made valuable and knowledgeable contributions. I know these have been appreciated by many members (including me), even those that do not contribute themselves or actively participate. The forum section would not be as successful or useful without them and the time and information they give freely.

Very occasionally a new member will join the forum and start to question not just the advice given but also the way the website operates. On the rare times this has happened it's usually because they haven't taken the time to check existing discussions (there's a pretty good search facility on the site to help with this) or read the instructions and guidelines and understand generally how the site works. 

So, let's take a breath and get back to what we should all be doing in this club - promoting the collection, preservation and display of old mowers.

OLC Admin

hillsider
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Thank you OLC Admin for those

Thank you OLC Admin for those well chosen words. None of us are too old to learn something new or to recognise when we are faced with something unfamiliar to us but constant reinventing of the wheel when we try to help is tiresome at the very least. As you say it is time to step back, draw a line under recent events and move on.