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NGK's Trident

7K views 37 replies 12 participants last post by  tridentt150v 
#1 ·
Going to try some NGK iridium plugs in my 74 t150. #7's or #8's?
 
#3 ·
What's the normal heat range for a copper core? Stuart says an Iridium plug has a wider heat range...Are you trying to mask an igntion problem? Have unusual riding conditions ? They are $25 for three? Perhaps try a NGK competition plug with the cut back ground electrode, about $3 each...They are non resistor....In my race bike I believe they made a very slight increase in power over the NGK fine wire plugs I was using...Supposedly the wider ground electrode have a stronger spark kernal..But the ony way to know is try them all ....:wink2:
 
#4 ·
Houston - so good to hear from you again.

Opinions are a dime a dozen, but a top Triumph mechanic who's been a factory-trained expert since '69 says NGK's threads often strip the aluminum threads on Triumph heads.......and I had that very experience using them on my '73 Trident.....
 
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#7 ·
I've been running NGK BR8EIX plugs on my 73 T150 for years. I pay $3.50 for them at Advance Auto. Bob
$8.19 each at Advance Auto here in NY, between $7-9 from all the other discount stores online...You're getting a deal...
 
#9 ·
The main risk is carbon build up on exposed threads...most don't have exposed thread (thankfully) but those that do - and it only needs to be half a turn - will work the thread every time you remove the plug. Carbon build up is hard and abrasive.

I have a head on my Trident [that I bought at a swap meet many moons ago] that had the centre hole damaged, and the other two not looking great. I used time serts on them and they are fine.

On my T140W the last turn or two are exposed, when I got the bike one hole had already been helicoiled [and it had very low mileage on it]. This only made exposed thread section longer....but the carbon didn't wear the helicoil out, all it did was pick it up and as the plug came out so did the helicoil. This happened to be in middle of nowhere at the end of the earth. I had to get towed for miles by my mate.

Needless to say I have now repaired that head with time serts as well.

I don't think the make of plug is an issue, but the exposed thread can be, you need to use plug washers to lift the plug and make sure that your thread is covered.
 
#15 · (Edited)
How interesting: My father worked as structural engineer at Hawker Siddley, then designer at Avro and finally chief designer, military in-flight at BAE so I know a little about this.

The reason HS brought metal works in house (by acquiring High Duty Alloys and others) was not a cost-saving exercise, it was to control quality. Previously they imported alloys, and some structural failures, with deadly consequences (e.g.wing spars and leading edge on the B1 Vulcan, such as at Syerston) were as a direct result of inconsistencies in 3rd party supplied alloys (very small differences in alloy composition but significant impact, quite literally...).

I will ask him if he was aware of Hawkers selling alloy or non-aviation castings outside the group as it surprises me. Perhaps this was actually before Hawker's acquisition? If so the quality and consistency of the alloy and castings on BSA and Triumph heads may still be in question. When HS bought HDA the company were one of those 3td parties supplying variable quality, once HS had acquired them, HS were able to control quality. Which was the whole point of the exercise.

However, I don't think Peg was questioning quality of metal directly, just the consistency in head manufacturing due to tired old processes and tooling at the factory. If HS made the heads for BSA and Triumph then I imagine they would be high-quality but it just seems odd that they would, knowing how they struggled to keep up with the HS demands.

Cheers,
Ian
 
#16 ·
Also keep in mind that the spark plug thread length is affected by the top of the thread. Repeated working of the thread can wear down the spark plugs seat. Next time you remove your plugs check it out, you will see a ring around the hole where the spark plug washer has been tightened [overtightened?]. This effectively shortens the thread and exposes thread in the combustion chamber, so it could have left the factory fine, but time and use has changed things.

IMO anyone that has their sparkplug holes helicoiled is asking for trouble. And it makes the fit even worse...because helicoil repairs rely on parent metal, so generally the helicoil is slightly shorter than the original thread = more exposed thread on your spark plug than you originally had. And by the way, if you have a helicoil that is longer than the parent material expect big issues because the exposed helicoil section will glow red hot and create pre ignition and all sorts engine damaging problems.

A timesert also relies on parent material but because of how it grips that parent material you can actually use one that is a few thou longer and once installed sand its back to the roof of the combustion chamber with no issues.

Lazy people try to fit thread repair kits in the bike using lots of grease to 'trap' the swarf...I have seen it done and yes it does work, but IMO it is really just a 'get out of jail free' card. Head off install is really the better long term dependable fix.
 
#17 ·
Hi Ian,

Excellent! :thumb New information about these old heaps decades after they were last made.

Certainly I know on triples, HDA heads (cast on them) are much preferred to "AM" (that company's name escapes me right now but I can find out), the latter more often being poorly-cast, infamously inside the centre exhaust port. :( Certainly some HDA heads have other letters cast or stamped on them, which aiui allowed a casting to be traced to both furnace and batch, which might've been part of HS's improved quality control process?

Hth.

Regards,
 
#19 · (Edited)
Okie Dokie we back about the use of various sparking plugs in Triumphs.

I was in error in that what I stated was not in an 'Official' Service Bulletin my mistake. It was, however, in the book given to the Mechanic's at the Factory Training Class held for Triumph Mechanics. The one I will quote from is from the 1978 Service Seminar.

In the book is the following statement: "Avoid using Japanese plugs. The threads are plated with a material the flakes and blisters, this in turn can damage the threads in the aluminum head. Also, there is NO Japanese spark plug with the exactly proper het range. Suggest using Champion N3 or KLG FE80." I would also point out in the book the word NO is underlined.

So do as you wish that was Triumph USA's advice to their Service people in 1978.


I also found an old Service Bulletin last night dealing with recommended spark plugs

Number : (GENERAL) 8/72
Subject : Proper Spark Plugs
Models : All
Date: 10/31/72

PROPER SPARK PLUGS

Recently an investigation of two 'B' Range units, which for no apparent reason, had suffered seized and holed pistons revealed that the failures were caused by the wrong spark plugs which were too hot.

In talking to the mechanics involved, we found that, during the routine service and tune-up, the Champion N-3 spark plugs had been removed and another brand installed, using a conversion chart to determine the heat range needed. This conversion chart was the start of the trouble, as the information was wrong, as is often the case. (Note in the Bulletin the word wrong is double underscored)

USE THE PROPER SPARK PLUG HEAT RANGE ( Note all capitals were used and this was also underscored)

We strongly recommend the use of CHAMPION spark plugs in our motorcycles due to their proven reliability; however if you choose to use another brand, be certain to use the proper heat range (SEE CHART BELOW)

(I shall not attempt to recreate the chart but will list the bikes and plugs mentioned)

Champion Normal street N-4 , High Speed Touring N-62
K.L.G. Normal Street FE80 High-Speed Touring FE100
N.G.K. Normal Street B8E High-Speed Touring B9E

The above plugs are for T100C and T100R models


Champion Normal Street N-3 High-Speed Touring N-60
K.L.G. Normal Street FE100 High-Speed Touring FE220
N.G.K. Normal Street B9E High-Speed Touring B10E

The above plugs were listed for the following models T25, TR5T, TR6, T120, TR7RV, T140V, T150V, TRX75.


Note the Bulletin was issued in October of 1972 so it would be applicable to 1973 models. Also please note the information from the 1978 Service Seminar would have been written PRIOR to the introduction of the T140E model.



K
 
#24 ·
The later parallel port head has more intake port velocity that the splayed port head..This gives a better/cleaner combustion burn necessary to pass EPA emissions..The hotter plug is part of it..
 
#26 ·
Agreed to a point.

If the head has that much better velocity the N-3 plug would not have been rich fouling. The US MKII carb was jetted fat on the bottom end and this caused the N-3 plugs to load up. The cold start jet was changed from a #50 to a #35 sometime during the 1979 model year and the recommended plug was changed to N-5 from N-3 about the same time. In my opinion the N-5 plug had to be used to burn off the low speed build up due to the somewhat rich carb settings at start up and low speed operation. Look at the wording of the Service Bulletin.

The US Model 1978 T140E passed EPA standards using a N-3 plug and a 50 starter jet.
By the way the N-5 plug is listed in the 79 up T140E Service Manual where the bikes have Euro jetting

When new the U.S. model T140E were a bummer to start. They were cold blooded animals. Customer's had problems with the enrichners operating system. Unless the carbs were aligned correctly the enrichners wouldn't stay on. The lever would get bent when guys try to hold it down when kick-starting. Guys used to carry 1/4" bits of wood to place under the enrichners lever to keep it up until the engine warmed up a bit. Alternatively some guys used their car key to hold up the lever. Also be aware if the vent hoses on the MKII carbs get pinched/pluged it will lean out the mixture often leading to holes in the Pistons.

K
 
#27 ·
I have a 79 T140D...I don't have the date of manufacture in front of me but what looks like original MK2's have #50 starting jets and the rest is the usual US EPA jetting...The cold start is far too rich to leave it on for more than a few seconds in 55F temps...I changed to the Euro Jetting...Then the cold start was better but they needed to be on for a long time because of the leaner pilot jet..
I swapped to Mikuni 32 MM TM flatsides.They are jetted on the lean side.The engine has Triumphs parts but is beyond stock tune.I still use a NGK #5 heat range..The ground strap discoloration shows it to be the correct heat range.
To be truthful I have never had plug fouling problems on any bike over the years...It's my opinion that many bikes are too rich from poor tuning or rider freak out over possible detonation...
 
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#28 ·
I use them in all my Brit bikes. 6 and 7’s with much larger gaps depending on tune, I rarely run 8’s..they don’t run hot enough to self-clean in my bikes.
I open the gaps till I see 13kv part throttle cruising load on the dyno. Usually results in a 40-50 thou gap using all stock and good ignition parts. Start at .035”
The iridium has a very low voltage requirement for spark allowing a much larger gap. The fact that they last longer is moot..you’ll change them long before they’re worn out.
If you have a means to check secondary voltage before you swap them you’ll see the difference can be substantial. Recently I swapped a set of good copper plugs firing at idle at 14kv to iridium firing the same bike less than 10 min later at 9kv idle.
Run the hottest you can without the insulator epoxy melting.
By the way..The temp of the plug has nothing to do with the engine temp.
Hope this helps.


Sent from my iPad using Tapatalk
 
#29 ·
My land speed racer Triumph on the track showed no perfromance advanatage with plug gaps larger than .028...Depending on igntion type, Lucas Rita being an example, a larger gap may reduce spark duration, but may be less of a factor with fine wire plugs. A larger gap may help with off idle hesitation...
 
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#31 ·
It seems to make a difference in stock bikes and bikes with minimal mods like air filters and exhaust. There are measurably less hydrocarbons suggesting a better overall burn.
I do know it made absolutely no difference in sohc Honda’s any way I tested it.
..must be a chamber design thing.


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#32 ·
Hi Truckedup



I did not know this, I’m searching for the 13/16 long socket and feeler gauges now.
If the engine goes slightly lean off idle it may help...
It seems to make a difference in stock bikes and bikes with minimal mods like air filters and exhaust. There are measurably less hydrocarbons suggesting a better overall burn.
I do know it made absolutely no difference in sohc Honda’s any way I tested it.
..must be a chamber design thing.


Sent from my iPad using Tapatalk
Oh I believe it... There is some talk that fine wire plugs have a smaller spark kernal than a conventional plug..I'll see if I can find the info..
 
#33 ·
On a forum with pro drag and circle track racers I asked about their experiences with Iridium plugs..This would be in auto use, mostly modified Chevy V8's...It seemed on the dyno Iridium plugs lost a few HP compared to conventional plugs in a few cases...One guy said the few HP came back when the timing was retarded two degrees...A guy who is an engineer for an auto manufacturer said the only reason they use Iridium plugs is to extend plug life to 100,000 miles or more for emissions requirements mandated by the gov't.
But if the wider gaps helps, and I know it can in some situations, and the ignition won't fire a conventional plug reliably with a wider gap, then iridium makes sense..
 
#34 · (Edited)
I am on a turbo car forum, it is common knowledge that once you up the boost above approx. 15psi the iridium plugs start to break down. The spark is blown out before ignition occurs. You cannot fix this for iridiums.

This can also happen with copper plugs, the two fixes are to reduce the gap from 1.1mm back to 0.8 or 0.7mm and/or use a better coil system with a stronger spark.
I am running with 20 psi, I have standard copper plugs, gapped down to 0.8mm and a set of stronger aftermarket coils.

I would be wary of even using iridiums in a hi comp motor tbh...they may work, but really...do you need the extra doubt/hassle?
 
#35 ·
I checked some turbo forums and some claim the iridium are good for over 20 psi boost.. There are some new turbo engines making more than 15 psi boot equipped with iridium plugs right from the factory?
However,I have heard the strories that iridium plugs can create a strong enough spark kernel to deal with high boost pressures or nitrous oxide..
As always, there are different opinions based on experience or just Internet BS.
 
#37 ·
I miss spelled a word...I meant to say "can't deal with high boost or nitrous" I hear one constant statement from race engine builders, Iridium plugs add about 2 degrees to the total time so be aware of this on modified engines...
 
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