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Discussion Starter #1
Hey Guys,

Was getting ready to order some new Spark Plugs for the 1970 T100C that I am finishing up. I have always run NGK B7ES. The manual for the bike calls for Champion N4, which according to the cross reference charts, corresponds to the NGK B7ES, which is what I have always used in the past.

However, I recently found an article in Vintage Bike Magazine which claims the following:

Don’t underestimate the importance of the proper grade of the spark plug: You should tune to the manufacturer’s recommended brand and grade spark plug.
The grade of spark plug recommended by the motorcycle manufacturer is an important base-line for carburetor tuning. If you are fouling the recommended spark plug you should never change to a hotter grade plug in order to correct the problem. You do this with risk of causing severe damage to the engine. he plug is not fouling because you have the wrong grade of spark plug.
All spark plug cross reference by brands are not always accurate for a particular motorcycle. After extensive testing at MIRA (UK vehical testing grounds) Triumph found that the NGK B8ES was not equivalent to the Champion N3. The B8ES was equivalent to a Champion N4. The B9ES turned out o be equivalent to a Champion N3.


This states that B8ES is equal to the N4 not the B7ES as the cross reference charts state.

What do you all think about this? I don't want to start a discussion about everyone's favorite spark plug brand, I only use NGK and that is all I will use. I have my reasons. I just want to know what to make of this article and if I should switch to the B8ES instead.

Thanks,
Rob
 

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If you have ran the NGK B7ES in the past to good effect then why change anyway? Stick to what you know works I reckon but I'm interested to see what other people think
 

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I have used B8ES for years in several Bonnies - never a problem

but as the saying goes - if it aint broke dont fix it
 

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Hi Rob.
Cold, N3-—, N4-—, N5—, Hot. Original Equipment.
Cold, B8ES, B7ES, B6ES, Hot. Conversion chart information.
Cold, B9ES, B8ES, B7ES, Hot. New Vintage bike magazine information.

I always find it hard to get my head around the equivalent heat ranges, champion numbers increase as the plug gets hotter, NGK numbers decrease as the plug gets hotter.

If Vintage bike magazine is correct then the error from the conversion charts puts the engine in danger from pre -ignition. Thwe have been using for years.
If you change to the vintage bike magazine recommendation then you are putting a colder plug in, this is not dangerous for the engine, but if they have got their research wrong then the plug might foul and the engine misfire.

Was there any more to the article," the extensive testing at Mira" is a pretty meaningless statement. Do they provide a link to the reports and test methods?

I think I would err on the side of safety and fit the colder plugs. If they foul then it is a quick plug change to rectify the problem.

Regards
Peg.
 

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some of these NGK nonresistor plugs have been discontinued, so it wont matter whether theyre recommended or not. iirc B8ES and B9ES are among them, cant remember about the 7s
 

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Hi Rob,

Here in GB, I can get NGK's easier than I can get Champions, simply because there are wa-aa-ay more Japanese bike dealers than Meriden Triumph dealers, and many of the Meriden Triumph dealers sell NGK's too.

I've run NGK's in my Triumphs since God was a lad. According to NGK's guide here, B8E... is equivalent to N3, B7E... is equivalent to N4. If you actually speak to NGK (I have), it isn't quite as simple as that, and I've run B8's in my T100 simply because it saves me buying two different plug grades. If the latter doesn't bother you because of your collection, put B7's in your T100?

Hth.

Regards,
 

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Discussion Starter #8
SpeedRattle - I'm not sure if they are discontinued or not, but I can still get B8ES and B9ES any day I want them and I run them in several other bikes I own and have never had a problem getting them, even from my local AutoParts store.

Stuart, your cross reference is the same as what I have here, but the article I referenced basically says that the cross references are wrong. That is what I was questioning mainly. I have always run NGK in every single bike I own and have a large selection of plugs in my shop, so switching to B8 versus B7 is not a problem for me. I was just confused that the article I read said that the N4 cross references were wrong.

Thanks,
Rob
 

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from dan's website at franz and grubb:

NGK DISCONTINUED WHAT???
NGK Spark Plugs (U.S.A.) has recently discontinued popular non resistor plugs that most Triumph motorcycles use. The non resistor part numbers are now superceded by resistor plug part numbers. This means if you order a B7ES they are suggesting you now use a BR7ES plug, which has a 5000 Ohm resistor built into the plug. This may not be an issue for some , but for those with E.T. or magneto ignitions, it may.
NGK Spark Plugs cancelled

IF YOU USE NGK B7ES... If you still want to use a non resistor plug and stick with NGK, you can either buy old stock plugs, or switch to a NGK V-Power racing plug. The equivalent to NGK B7ES in a V-Power Non Resistor plug is NGK part number R5671A-7. This plug would be a great substitute but uses a smaller 5/8" hex size and the non removable solid terminal may not work with some NGK plug caps.



you can take the resistors out. i don't know what other changes might be made to the plugs
 

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Hi Rob,

Apologies for the delay replying, I wanted the opinion of a guy I've known since the early days of the TR3OC in the 1980's; he's both raced triples and I know he rides them hard on the road. Unfortunately, we both have Gmail addys and for some reason, Gmail is currently having a random problem, messaging it (Gmail) can't "verify" another Gmail addy (effing computers ... they'll never catch on ... :mad:). Anyroadup, some human intervention and common sense and he was able to advise ...

He says he's always used B8ES's instead of Champion N3's, without any problems at all. It occurred to me also that Triumph hiring MIRA for testing can't have been later than the early 1970's ... i.e. half-a-century ago ... Certainly his and my experiences using B8's are all later.

Reason I'd talked to NGK is I've always used B8's with one or other of the unobtainium/costalotium centre electrodes, which have a wider heat range than the conventional -ES's and, because I have to buy 'em in fours minimum, I wanted to know if I could get away with one plug for both triples (N3 originally) and the T100 (N4 originally). So far ...

Hth.

Regards,
 
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