Track day on standard NX4

[dandywarhol]

Are the stock TRX plug cap resistor caps cobba?

[cobbadiggabuddyblooo]

No, pointless running resistor plugs and resistor caps.

[dandywarhol]

I thought that might be the case - old HT leads were carbon strings under the insulation which had a built in resistence to cut out "noise" but if fitted along with resistor plug caps would cause a poor spark under duress

[Racer-unk]

http://www.ultralightnews.ca/articles/r ... dplugs.htm

Interesting read on spark plug caps

[dandywarhol]

http://www.ultralightnews.ca/articles/r ... dplugs.htm

Interesting read on spark plug caps

Haaa - I found that too

[dandywarhol]

Ok, just to add more fuel to the spark - the stock TRX plug caps ARE resistor caps - to the tune of 9.7k ohms. I suspected this earlier and confirmed it on mine today.

Yamaha recommend NGK DPR8EA plugs which have a built in resistance of 5k ohms. As these are in series then the total resistance in the coil/plug circuit is nearly 15,000 ohms.

So, while you're all chasing for the fat cat spark - why not just remove some of the resistance to flow? A non resistor plug would be a start..................... Nearly 10k ohms in the cap should be enough to suppress radio/tv etc?

Thoughts?

[Rod.s]

Some museing

This is an age old debate, and one that should still be debated. As we strive for more power or better still cleaner delivery of that power the inevitable question of resistor plugs comes up, do you want a short intense spark or does your engine perform better with a longer reduced spark? Hey, they're track bikes so why not experiment and as plugs and leads are relative (to other wholehearted changes) cheep, change them and see what the feel is. I recommend running the coils straight from the battery Via a relay, max voltage gives max spark.

Or as a friend who's runs a CBR250RR (strictly track bike) has done, his coils are powered by a 18volt cordless drill battery (via relay), still switched by the ignition and the battery changed after each session. He has developed his aftermarket ignition module to have a reduced "on time" for spark and it is also has extra cooling, Yep the coils do get hot but are quite happy after a year of track work, with no overvoltage damage or failure, remembering it is a 250 and he needs all the help he can get!

The TRX is a dynamicly different engine and with it's coils already being overdriven by a few volts at high RPM. And changing the plug gap will also effect the delivery as this gap is also a resistor of sorts.

NGK's web site is a good place to start, well they do know sparkplugs

WHEN SHOULD I USE A RESISTOR SPARK PLUG?
A: NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.

NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.

In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion.

[cobbadiggabuddyblooo]

Ok I'll ignore what I was advised that their will be an " R " stamped on the cap if it's a resistor cap.
Thanks for the clarification Dandy...

[dandywarhol]

Good shout Rod.

I'm still surprised that Yamaha use both resistor caps AND plugs.

In the bad ol' days before electronic interference causing problems on board, autos used carbon string HT leads with built in 10/12 kohms of resistance and NON resistor plugs. This was enough to stop folks TVs and radios sizzling when you drove past.

The TRX isn't that much further advanced requiring screening for on board whizzery

[Racer-unk]

all above been said....I cant find a non-resistive Caps anywhere... I will take my chances with either a 5k or 1k cap (if I can order them) and no resistor plugs

[Racer-unk]

so my mates are doing the free Track-day practise tomorrow and I must pay to play in a Bowls Competition I was invited to play....Damn clashing calendars...Hope I can concentrate tomorrow

[coxylaad]

So in summary. Replacement copper HT leads with standard plug caps will reduce the designed resostance of the ht system, giving a better spark but potentially causing noise ?

[dandywarhol]

In summary. Copper cored leads have virtually zero resistance. Standard setup is resistor plug caps and resistor plugs. With non resistor plugs there is the possibility of suppression noise - depends how far away your neighbours and how much you give a fuk

[Racer-unk]

i prefer your stance Dandy......as little resistance as you can get away with. Otherwise the hard work wiring those relays in, counts for nought

[coxylaad]

What about affecting the ecu on your bike? I presume that is shielded? Also remember mine is injection too