The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: A10 JWO on 23.02. 2013 14:55
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Firstly I am sorry for starting this thread.
I have been reading all the old threads for spark plugs and Champion came out best, I thought. I bought my 1954 Iron Head A10 in October and it was fitted with Volvo spark plugs : )
I bought NGK B6HS from a local car spares shop and it started pretty well most times. I visited my local BSA spares shop yesterday and he recomended Champion L82C for a better starting plug. I set them at 18 and fitted them. Would it start NO !!!
I put the NGK's back in and it fired first time.
Just thought I wouls share this moment with others who may know why my bike does not like brand new Champions.
Enjoy the rugby
Colin
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I visited my local BSA spares shop yesterday and he recomended Champion L82C for a better starting plug. I set them at 18 and fitted them. Would it start NO !!!
Did you get your money back?
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Not yet, but I would like to know why they don't work in my machine, are they a summer plug LOL.
Colin
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Must be bad plugs, that's all. Next Champions you try might be ok.
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Mine doesn't like Champions either! NGK might be a better option, or Denso's which are harder to get but since modern 'petrol' work best for mine.
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NGK's for me. I must have bought 10 champs out of the same bad box 30 years ago. Used NGK's since and would say I might have got 3 duds in that time.
I've just started using iridium plugs in the cafe and so far so good.
Cheers
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Our latest club magazine mentions counterfeit NGK plugs.
There is a lot about this on the web. google 'counterfeit NGK'
With some of the NGKs I've used, they may be better than the real thing.
cheers
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I've used Bosch to good effect, also there are non resistor plugs with small diameter centre electrodes the run clean,
I'll post back when I've been down to the shed sometime
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Normally I wouldn't put a Champion in a lawnmower! However, they are the only plug that works in my 61! It fouls NGK's very easily. Too much tickler and they are done. I use the exact model called for by BSA.
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I know that some plugs are just better than others and there must be some percentage of failures out-of-the-box, but I am having a hard time wrapping my head around total inoperability with one type versus another. Not doubting it, because there are plenty of stories to back it up, but I'm fishing for a good reason. You couldn't find a simpler piece of electrical equipment. Really, just two pieces of wire, an insulator and two electrical joints.
So, here are some unsupportable theories in no particular order:
1. Length of thead, either on the plug or in the head, leads to the grounded electrode shading the spark more than exposing it.
2. Technique of fusing grounded electrode to plug body (resistance welding) might create a high-resistance joint. Likewise, cap to insulated electrode.
3. Alloys used might also lead to resistance in joints.
4. Bad batches of ceramic mix for the insulator could lead to unseen hair-line fractures along which spark could travel.
5. Ceramic crystal structure might promote spark travel even when not fractured (talking way outside any technical expertise in this regard - maybe applies to the whole topic).
6. Plating of cap material or plug body could create resistance.
7. Any of the above in combinations
Looking forward to hearing more possibilities or learning why these are ridiculous.
Richard L.
Editing
Thanks Bill, adding to the list:
8. Lack of glazing could lead to the ceramic absorbing liquid and creating a spurious path for spark travel.
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yes best theory I've heard is related to number 4, the author reckoned that because of the injection methods now used the plug manufacturers found no reason to glaze the internal ceramic insulator this results in plugs that once wetted become a complete conductor back to the engine body as the ceramic not being glazed just soaks up the fuel and the spark has no need to jump anywhere it just dives across to ground, might or might not be correct but it answers a few questions
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I read the comments about counterfeit NGK plugs with interest as I had recently bought a box of B-7HC plugs for my A10 plunger a while back from the States through eBay which were advertised as NOS as I was having difficulty sourcing them here at the time. I decided to check the plugs just to satisify myself that they were the genuine article and found several of the indicators mentioned that they were in fact counterfit plugs such as the box colour and missing stamps on the hex part.
I asked my local motor parts shop to order some and when I got them I found that they were B-7HC-10 which have a slightly different electrode design. I take it that these will be OK?.
I have been using the (apparently) counterfit plugs for a while now in a recently rebuilt engine. Having seen some of the comments about holed pistons when the plugs go into melt down I guess I may have been very lucky..!!. I bought some B6ES plugs for my Norton at the same time from the same shop but these seem genuine. The plugs were not particularly cheap, much the same as what I paid for the replacements.
Cheers,
Peter
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Might it be a alloy v iron head thing. NGK and Champion are opposite in their heat range #'s, NGK 5 is hotter than 9, Champs the other way. If it's fouling plugs throw some hotter ones in.
Cheers
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Colin after reading this forum I have gone to NGK no problems have had issues with champions in the past with a Tri 500 and my B S A under restoration much better John
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Glad you like them, NGK are good ( so are Volvo plugs ) That's what were in mine when I bought it.
Happy days.
Colin
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i have been using champion n5 plugs in my my rocket with twin carbs and 10 to 1 pistons and believe it or not i used an L 10 in a zb32 i used to race nearly 50 years ago i dont know what to think.
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I could nearly bet Chris that if you still have that 50 year old L10 it would still work fine, a new L10 bought today would be a different story.
OTOH would you like to pay today's equivalent of the 3/6d the L10 cost 50 years ago - maybe I don't know what that would be
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they were 5bob then and i thought things were supposed to have progressed and improved over time but not so it would seem in the case of sparkplugs.
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I could nearly bet Chris that if you still have that 50 year old L10 it would still work fine, a new L10 bought today would be a different story.
OTOH would you like to pay today's equivalent of the 3/6d the L10 cost 50 years ago - maybe I don't know what that would be
When I left school in the mid 60's I worked in a garage filling fuel tanks, (in those days you didn't serve yourself). You could buy 4 gallons of petrol for a pound and 4 spark plugs were also a pound.
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4 spark plugs were also a pound.
they were 5bob then
Guys your right they were 5 Shillings (Bobs indeed) for what seemed years on end.
So where did I get the 3/6d - that was the price of a gallon of petrol when I first started (1960)
that makes the plug almost 50% more then a gallon of petrol (very roughly) taking to extremes at today's fuel prices a plug should be around £8.50, actually aren't some about that
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When I left school in the mid 60's I worked in a garage filling fuel tanks, (in those days you didn't serve yourself). You could buy 4 gallons of petrol for a pound and 4 spark plugs were also a pound.
a bit off subject but you could also get a shot of redex for a penny *smile*
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1) There is no profit in making standard plugs.
2) Standard plugs were designed to burn a non existant substance called "petrol"
3) NGK's tend to have "finer" settings than Champions. there are oft 2 or 3 NGK's spaning a single Champion grade.
4) I have seen just as many "standard" plugs of any brand of any age go bad directly out of the box
5) modern "fuel" which is not petrol is highly conductive so if it wets the plug then it is "all over red rover "
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Well blow me down.
Today I fired up the old girl after fitting a new SRM pump. After 30 seconds a gushing oil return. But ! It was firing on one cylinder R/H. I swapped the NGK plugs round and then it was L/H. Only three miles from new *sad2*. I found the new Champions I bought months ago which did not start the bike when new. Fitted the new ones and fired on all pots first kick. No logic to it ( confused.com ) I am.
Colin
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Hey Colin,
Almost 200 postings on the forum and welcome to the wacky world of classic bikes. Some things that should be explained can't be explained. Some things that can't be explained should be explained. It's all part of the adventure but when frustration sets in it sets in big style.
Enjoy your rides and remember....more miles means more smiles.
Beezageezauk.
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Can someone quickly confirm whether our 'A's use a 10mm or 12mm spark plug? I am at work and want to buy a Colourtune on my way home but I notice that there are two models available and I want to make sure that I get the right one!
Cheers! *smile*
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14 mm isn't it?
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Are you sure? I am now looking at this the other way round. Most people seem to recommend using NGK B6HS plugs in their bikes, but these seem to be a 14mm plug. I am getting more confused now!
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M14 x 1.25 = NGK "B" range, B7ES for alloy head, B7HS for iron head.
http://www.ngk.com.au/spark-plugs/product-information/part-numbering-system
Cheers
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Mosin as soon as I hit the enter I remembered it was 14mm *doh*
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Are we talking about thread length or diameter?
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Diameter. Lengths are 1/2 inch in iron heads and 3/4 inch in Alloy heads.