Plug pics

comnoz · Sep 22, 2014

Reggie said:
These were my plugs after a 1,300 mile tour of France. I was getting more than 60mpg (Imperial gal) two up with luggage, although I wasn't nailing it! Based on Jims comments about

No black pepper flakes or shiny balls that would indicate fast timing or very lean mixture.

Click to expand...

I assume this is what you're talking about?

The carbs that did this have been consigned to my spares pile as I'm now running FCR's.

No pepper flakes there. Just a lot of buildup either from fuel additives or a little oil consumption or maybe extended warmups with the choke on. Jim

Hobot · Sep 22, 2014

Them worn out plugs look worse than what I see in long used lawmowers.
I got poo-poo'd here reflexly in past when I mentioned that a close to perfect best power engine tune gives some mild detonation which almost any engine like our ole Norton can tolerate a long time as long as not pushing into major detonation.

ludwig shows us the proof and likely also gets away with it by the cold air. Ludwig maybe ya could add a knock sensor like comnoz then see if ping detectable tuning up and down a bit for sense of how close to major detonation you've gotten away with - like most of us seek too.

comnoz · Sep 22, 2014

hobot said:
Them worn out plugs look worse than what I see in long used lawmowers.
I got poo-poo'd here reflexly in past when I mentioned that a close to perfect best power engine tune gives some mild detonation which almost any engine like our ole Norton can tolerate a long time as long as not pushing into major detonation.

ludwig shows us the proof and likely also gets away with it by the cold air. Ludwig maybe ya could add a knock sensor like comnoz then see if ping detectable tuning up and down a bit for sense of how close to major detonation you've gotten away with - like most of us seek too.

I would agree that you can get by with light pinging as long as it is so light that you can't hear it. If you start hearing it you better do something quick. Jim

john robert bould · Sep 22, 2014

If the plugs look like this, whats the rest look like? Surly the exhaust valves ,piston crown dont have the same deposit's.?

comnoz said:
Reggie said:

These were my plugs after a 1,300 mile tour of France. I was getting more than 60mpg (Imperial gal) two up with luggage, although I wasn't nailing it! Based on Jims comments about

No black pepper flakes or shiny balls that would indicate fast timing or very lean mixture.

Click to expand...

I assume this is what you're talking about?

The carbs that did this have been consigned to my spares pile as I'm now running FCR's.

Click to expand...

No pepper flakes there. Just a lot of buildup either from fuel additives or a little oil consumption or maybe extended warmups with the choke on. Jim

pete.v · Sep 22, 2014

hobot said:
Them worn out plugs look worse than what I see in long used lawmowers.

I will bet those iridium plugs arn't that worn out or that old.

Hobot · Sep 22, 2014

The white crust is from lots of fuel additives with hi mileage accumulation not necessarily anything wrong. Wonder if ya can detect any change with new plugs?

comnoz · Sep 22, 2014

Here are the plugs from my bike. 4700 miles -no plug chop. I just looked and screwed them back in. Jim

L.E.N. · Sep 22, 2014

I guess I'm showing how much I don't know, there doesn't appear to be any ground electrode on those plugs. Are those the "plasma sprayers" that hobot Steve was talking about?

Hobot · Sep 23, 2014

Jim's plugs are the old fashioned updated 'surface' discharge which I've found to be extra forgiving to wide mixture variations. They will work for plasma ignitions as somewhat similar but are not really made for discharge spraying-projecting plasma. Plasma is strange stuff as its part of electrical sparks and cavemens fires to nuclear reactions. Plasma plugs similar to Jim's have slots in the surface to help direct jets in an outward fan. Jim's plus are actually most similar to oil foul proof plugs with hidden electrode behind a small hole.

comnoz · Sep 23, 2014

L.E.N. said:
I guess I'm showing how much I don't know, there doesn't appear to be any ground electrode on those plugs. Are those the "plasma sprayers" that hobot Steve was talking about?

They could be with a plasma ignitor but they are just surface gap plugs.

As cold as you can get and no side electrode to glow and cause pre-ignition. You have to have a hot ignition and a clean running motor to use them. Jim

Fast Eddie · Sep 23, 2014

I ran surface discharge race plugs in race bikes when I discovered that normal plugs would give in in less than one meeting, whereas proper race surface discharge plugs would last a whole season and even then I'd only change them as a precaution.

But @ Jim, in laymans terms please, what are the advantages in your bike? Do they give a better spark?

comnoz · Sep 23, 2014

Fast Eddie said:
I ran surface discharge race plugs in race bikes when I discovered that normal plugs would give in in less than one meeting, whereas proper race surface discharge plugs would last a whole season and even then I'd only change them as a precaution.

But @ Jim, in laymans terms please, what are the advantages in your bike? Do they give a better spark?

Thy are just very cold so that reduces the chances of pre-ignition.

Also the hot ignition I am using tends to erode the side electrode on one plug as I am running a single coil so one side electrode is negative and the other is positive. The plug with the negative side electrode erodes pretty quickly.

I could run double platinums to solve that problem but surface gap plugs give me a little more pre-ignition tolerance and don't erode. Jim

comnoz · Sep 23, 2014

[quote="hobot" Jim's plus are actually most similar to oil foul proof plugs with hidden electrode behind a small hole.[/quote]

Actually they are far from old oil proof plugs. The tip of a surface gap is completely open and the very short path across the insulator to ground will insure that any deposit on the insulator will short circuit the plug.
They are not tolerant of oil consumption or rich mixtures at all. If you have ever played with an old H2 Kawasaki or even an old boat motor you will find that out quickly. Jim

johnm · Sep 23, 2014

Following Mr Gordon Jennings's advice I settled on and now only ever used normal boring NGK BP9ES plugs in my 500 race bike. Magneto ignition fuel 98 octane NZ pump gas or methanol. Check that the projected tip doesnt hit the piston. They seem to work fine for racing conditions. (Maybe I should go a bit warmer for methanol?? BP8 ??)

http://ngk-sparkplugs.com/bp9es-p-2114.html

Fast Eddie · Sep 23, 2014

comnoz said:
Fast Eddie said:

I ran surface discharge race plugs in race bikes when I discovered that normal plugs would give in in less than one meeting, whereas proper race surface discharge plugs would last a whole season and even then I'd only change them as a precaution.

But @ Jim, in laymans terms please, what are the advantages in your bike? Do they give a better spark?

Click to expand...

Thy are just very cold so that reduces the chances of pre-ignition.

Also the hot ignition I am using tends to erode the side electrode on one plug as I am running a single coil so one side electrode is negative and the other is positive. The plug with the negative side electrode erodes pretty quickly.

I could run double platinums to solve that problem but surface gap plugs give me a little more pre-ignition tolerance and don't erode. Jim

Thanks Jim.

Your explanation raises the question of 'coldness'...

If a stock, low CR 850 is happy on number 7s, how cold would you advise running in my 850 with its FCRs, JS1 cam, 10:1 CR and a rider with a habit of enjoying the performance on offer?

I'm thinking that number 8s as minimum, would you suggest colder still?

comnoz · Sep 23, 2014

Fast Eddie said:
Thanks Jim.

Your explanation raises the question of 'coldness'...

If a stock, low CR 850 is happy on number 7s, how cold would you advise running in my 850 with its FCRs, JS1 cam, 10:1 CR and a rider with a habit of enjoying the performance on offer?

I'm thinking that number 8s as minimum, would you suggest colder still?

I would use 8's for street and 9's for racing or dyno pulls. Jim

comnoz · Sep 23, 2014

johnm said:
Following Mr Gordon Jennings's advice I settled on and now only ever used normal boring NGK BP9ES plugs in my 500 race bike. Magneto ignition fuel 98 octane NZ pump gas or methanol. Check that the projected tip doesnt hit the piston. They seem to work fine for racing conditions. (Maybe I should go a bit warmer for methanol?? BP8 ??)

http://ngk-sparkplugs.com/bp9es-p-2114.html

I would run as cold a plug as you can get by with. If it's too cold then you will have fouling problems.
Hotter plugs do not give better performance -they just clean themselves faster.

Surface gap plugs will not work very well with a Magneto, the voltage rise time is too slow and spark is likely to be bled off over the short insulator path causing missfires.
CDI [or one of the new plasma ignitions] is recommended for surface gaps. Jim

Hobot · Sep 23, 2014

Mostly teasing Jim about anti-foul plugs which are just a normal hook plug with a cap/shield over it so oil can't get in to crust up. As for surface gap needed right on mixture, only the ThunderFire surface discharge plugs of the early '70's allowed the P!! dragster tune very rich to run at city legal speeds w/o sooting up the plugs and dying from one intersection light to another. On each start up after a short idle time there'd be a few dark puff/smoke rings shot out to stain stuff behind me on each start, like 2 throttle blips then ready off idle snaps to smoke tire in place w/o thought or need of brake. Pure dumb luck to get such a beast and didn't know nothing and reason I got the bike is wouldn't run off track - til JC Whittney plugs saved the day. It taught me alot about good plug function.

Fast Eddie · Sep 23, 2014

comnoz said:
Fast Eddie said:

Thanks Jim.

Your explanation raises the question of 'coldness'...

If a stock, low CR 850 is happy on number 7s, how cold would you advise running in my 850 with its FCRs, JS1 cam, 10:1 CR and a rider with a habit of enjoying the performance on offer?

I'm thinking that number 8s as minimum, would you suggest colder still?

Click to expand...

I would use 8's for street and 9's for racing or dyno pulls. Jim

Thanks Jim.

Brooking 850 · Sep 23, 2014

Hi guys, loving this thread, not in a position to post pics of mine out of the race motor, but has anyone got any pics (good or bad) of plugs running Avgas so I can compare apples to apples?
I am running 10:1 CR with JS2 cam as per JS recommendations with cam advance.
Ignition advance is nominally 31 degrees, although Jim C recommends pulling it back a couple of degrees.
Ignition is crank mounted RCR (nothing in the cam end cavity under the points cover)
Regards Mike

Plug pics

Similar threads