Autolite AP63 Plugs

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Dec 24, 2003
It seems that the Autolite AP63 Platinum plug could be a good thing.

After reading about them elsewhere on this forum, I wanted to ask the question.

It seems Matt of CNW has decided they are worth using.

Are they a good thing to have in your norton ?
Good Day,
Does anyone know if Autolite Platinum Plugs are resistor-type? I would assume that they are as just about every plug is these days but I just want to be sure.

The reason I ask is the Sparx 3-Phase solid state rectifier/regulator that I am running requires that resistor plugs be used to prevent damage to the electronics.

Anybody running a Sparx and AP63/64's?

BTW, AP63/AP64's are available at UAP/NAPA here in Canada ($9.00 each + applicable).

Thanks in advance,

$9.00 EACH??? If so, wow. I bought a box of four from my local NAPA store here in Colorado for under $9.00 including tax. That's american dollars not canadian but still quite a diff. Is everything else that expensive up there?

Yeah, I was kind of taken back by that as well, considering that I can buy a pair of Bosch WR7DPX's at Walmart for $5.99 + tax (15% here in Ontario). NAPA is about the only place up here that actually handles Autolite Platinums, not much call for them up here I guess.

Thank god the Norton only has 2 cylinders!

BTW, I e-mailed Autolite with my question. The part number break down on their website was not very conclusive.


Sorry, I forgot. Why we are so enthusiastic over the Autolite plug?

The Autolite AP 63 does not cross reference to the recommended Champion N7Y plug. So, is the AP 63 a hotter plug? And if so, shouldn't we be cautious when using them, especially at high speed?

Yeah, norbsa turned me on to them also. I'm using the AP64s. I like them because they get my bike thru the critical first two minutes without fouling out like the other plugs. They let me ride my bike while I keep working away at the many electrical problems that continue to plague it.

Now that I look back at that post again, it seems that the answer to my question is in there as well!! Funny how things work out. Thanks, Jason!!


Why use Platinum tipped Spark Plugs ?

Why use platinum tipped spark plugs ?

Platinum is one of the most durable metals available for use in spark plug tips.

Due to its durability, it virtually reduces all gap erosion, which will give you performance benefits of:
• Better performance
• Quicker starts
• Fewer misfires
• Faster acceleration
• Smoother idle

There are two ways to get platinum into your spark plugs:
• Single platinum plug, which has platinum tip on the center electrode.
• Double platinum plug, which has platinum tip on the center and side wire. Double platinum helps enhance performance in the newer high-tech ignition systems.

You are also given a 3 year unlimited mileage guarantee.

So there you go, mad if you don't :D
Dear guest,

Your claims about platinum spark plugs for use in Norton engines is ambiguous. What exactly do you mean by: better, quicker, fewer, faster, smoother? Better than what? There is virtually no difference in performance between a new non platinum plug and a new platinum one.

Platinum plugs simply last longer than non platinum plugs.


I ride my bike hard 6500 rpm is hit every time I go out I can't stop myself. So I break things a lot. All kinds of things. There are many things I don't like about AP64 plugs: no nickel plating being at the top of the list. I have tryed many Plugs and find these to be the toughest agaist gas fouling. They were sold to me by a friend that works at an Advace Auto parts store he said they were the equivlent to Bocsh WRP7's that I have used for years. They are also the easyest Platnum plug to read. Now I have freinds with Nortons that never run thier engines over 5000 rpm they think I am nuts and can't see why those Champian plugs just don't work for me. But they also read thier plugs like thier Dad's taught them and gripe about unleaded gas. Most of the time they go the speed limit too. So It's all about how you use your bike and how you tune your bike and were you live and the kind of gas you get. Now if I can just find some tires that will last. norbsa
I wouldn't have believed it if I hadn't witnessed it myself: the Autolite's do seem to work better than the Bosch's.

My Bosch's were only about a month old, I changed them due to a cracked insulator. I noticed no real difference in performance between the used and new Bosch plugs.

First impressions with the Autolites:
Starting is easier. The bike was always a one kick starter, but it had to be one healthy kick. Now a less enthusiastic kick will start it no problem. The idle is firmer and it will actually idle at a lower engine speed. Power delivery above 6000 rpm is also smoother. Easy redline in 3rd, 6500 top out in 4th. Acceleration above 70 mph is much improved.

Jason, I know your skeptical. You're right, there are no quick fixes when tuning an engine. You will just have to come up here and ride my bike!! :D

(Norbsa: Bridgestone BT45 Battlax 110/90-18, 4000 miles, still lots of tread)


I've noticed similar benefits with the AP64s in my 750. Seems like I don't have to kick it as hard although that could be from tuning, don't know. It's definitely idling a lot better. I have a nice smooth steady 1000 rpm idle now and my amals are not that fresh. Slides are a bit loose.

Had the bike up to an indicated 80 mph this weekend. Felt smooth and strong. Seems like those plugs are the way to go!

So...It appears that Autolites AP63/64s may be a good thing then.

That was my original question when I posted this topic.

I also picked up on norbsa's comments in another post, thanks norbsa.

Personally, I feel that they perform well also.

I have also increased my main jet size by one step(10) & find that my bike now pulls more strongly in top at about 3,800 rpm with a 21 tooth sprocket.

So when would be a good time for me to come up and ride your Autolite equiped bike? Also, which Autolite plug crosses over to a Champion N7Y?


Hey Jason, Once your up to Derek's place I am only about 130 miles away. Two test drives better than one. norbsa
Hi Norbsa,

I would love to visit with you!

We could talk about machinery in general and the second law of thermodynamics! I've got scads of frequent flyer miles I need to take advantage of. Have you ever calculated adiabatic gas expansion?

No can't say that I have. Now Dyno Dave may be up on this. He's just a hop further.

Isothermal and adiabatic expansion
Suppose that the temperature of an ideal gas is held constant by keeping the gas in thermal contact with a heat reservoir. If the gas is allowed to expand quasi-statically under these so called isothermal conditions then the ideal equation of state tells us that

This is usually called the isothermal gas law.
Suppose, now, that the gas is thermally isolated from its surroundings. If the gas is allowed to expand quasi-statically under these so called adiabatic conditions then it does work on its environment, and, hence, its internal energy is reduced, and its temperature changes. Let us work out the relationship between the pressure and volume of the gas during adiabatic expansion.

According to the first law of thermodynamics,

in an adiabatic process (in which no heat is absorbed). The ideal gas equation of state can be differentiated, yielding

The temperature increment can be eliminated between the above two expressions to give

which reduces to

Dividing through by yields


It turns out that is a very slowly varying function of temperature in most gases. So, it is always a fairly good approximation to treat the ratio of specific heats as a constant, at least over a limited temperature range. If is constant then we can integrate Eq. (6.57) to give


This is the famous adiabatic gas law. It is very easy to obtain similar relationships between and and and during adiabatic expansion or contraction. Since , the above formula also implies that


Equations (6.60)-(6.62) are all completely equivalent.
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