Spark plugs (2016)

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John leathers

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Oct 24, 2014
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I am having trouble with the spark plugs keep going faulty. It is running on champion n3c only done about 12miles and gone through 2plugs already, at this rate it is going to be expensive to run. Bike is a 1971 commando nut and bolt rebuild. Any info on this is most great full. John. Uk
 
Or, NGK BP7ES.

(BP7ES and N7YC are projected electrode plugs. N3C isn't.)
 
The N3C is a non projected plug and pretty cold on the list. I am sure you need a projected type plug and most certainly hotter.
Low numbers for champion plugs are colder whereas low numbers on NGK are hotter.
Play is safe and get a set of NGK BP7ES's. They are both a projected type and hotter. Standard equipment. You may want to try BP6ES's if you still have fouling issues, but I think you maybe ok.
 
If you can post a photo of the fouled plugs perhaps the problem could be determined.
Fuel or oil fouled?
Leaking fuel taps flooding the head while parked?
Smoking exhaust while running?
Weak spark?
 
pete.v said:
The N3C is a non projected plug and pretty cold on the list. I am sure you need a projected type plug and most certainly hotter.
Low numbers for champion plugs are colder whereas low numbers on NGK are hotter.
Play is safe and get a set of NGK BP7ES's. They are both a projected type and hotter. Standard equipment. You may want to try BP6ES's if you still have fouling issues, but I think you maybe ok.
Click to expand...

I've been advised twice this week on this forum not to use the BP6ES plugs, that they are too hot and severe damage may occur. They are standard in older Triumph twins, so no idea why they would be too hot for a Norton.
 
Around here the local bike shop say BP7ES not available anymore , so went to NAPA , same story .... ended up with BR7ES , I'm guessing that means resistor , I am running Boyer MK4 .... so am I all right , and where to find BP7ES in Canada ?
Craig
 
Thanks Toronto .... you are referring to the BP7ES at Walridge right , or were you talking about the BPR7ES ...
Craig
 
Danno said:
Also, what would be the advantage of projected-tip plugs?
Click to expand...

Gets the kernel (start of ignition) closer to the center of the combustion chamber so less time for flame to travel and consume air/fuel. This translates to less ignition advance required, always a good thing. Yes, it makes a difference; look up plug indexing to get a sense of how sensitive this can be.

The extended tip may also stay cleaner but that is speculation on my part.
 
John leathers said:
I am having trouble with the spark plugs keep going faulty.
Click to expand...

When you say faulty, do you mean covered in black soot (too rich mixture) or physically wrecked (mechanical, too hot, other). There's no harm in cleaning the plugs while you get you carb settings tweaked.

BC 71 Commando
 
I just found a stash of NOS Champion N4Gs. They were my fave plug back in the day. Less foul-prone than almost anything else. Had the BP6ES plugs back in there this afternoon for a little fine tuning of the Amals. Cranked out the pilot screws another 1/2 turn (both are now at 1 3/4 turns out) and reset the idle. The N4Gs should be here in a day or two and then I'll take it out for a bit more of a ride.
 
Bike is hard to start as seam to be on one cylinder, feel exhaust pipe one hot one cold. Remove plug it seems a little wet with slight oily look to it. Does not look fowled . Put plug in ht lead kick bike over and spark perfect, put in bike runs on one cylinder again. Seams like the plug is braking down under pressure. (New single coil pack, Boyer ignition ) timing 32d with strobe, fuel new super unleaded, single carb running a bit Ritchie, got some bp7es plugs coming. John. Uk
 
John leathers said:
feel exhaust pipe one hot one cold.

(New single coil pack, Boyer ignition )
Click to expand...

What about plug caps and HT leads?
All new?
Resistor or non-resistor plug caps?
Copper or carbon HT leads, or are the leads part of the dual coil?
Dual coil make/primary Ohms rating?
Have you tried swapping the plugs/caps/leads over?
Any noticeable difference in compression between the two cylinders?

Which particular "Boyer ignition" is it? Micro MkIII, MkIV, Micro-Digital or Micro-Power?

http://www.boyerbransden.com/productinfo.html
 
Funny how I see no mention of counterfeit plugs which were common a few years ago and which gave owners problems...the subject took up a lot of room on forum sites etc at the time...
if you believe the problem is the plug and not you (wrong grade of plug...carburation problems) might I suggest you take the trouble to return your faulty plug to the manufacturerfor them to examine. it only takes one phone call to find the name and address of the correct person to return it.... well it does in my experience anyway.
I once returned a certain manufacturers earth leakage breaker that didnt when it should of (which made life exciting at the time) and the following day found two new ones and a big box of new plugs on my doorstep.......
Its amaziong what some parts of the World produce...it was not that long ago a factory in I believe China was closed for producing counterfiet toothed belts......wonder if it is still closed?
 
With the NGK BR7ES installed bike started and idled as usual .... if I can't locate BPR7ES plugs before tomorrow , will I damage anything using the non projected BR7ES while waiting for the proper plugs .... I have some used BP7ES that I could clean up and use if there is a possibility of damage from the BR7ES plugs .... thanks
Craig
 
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