Date: Sun, 7 Jun 1998 23:21:36 EDT
From: Stan Smith
In a message dated 98-06-07 16:17:24 EDT, dryheat writes:
>Gentlemen, I request that we start a new thread. I have been told
that the
>quality of modern gas, being slightly oxidised, requires a different
>reading of the plugs than circa 1973. Theory being that now we read
only
>light tan deposits up near the normally white insulator tip versus
a
>"heavier" reading deemed to be perfect in the olden days. Comments?
John -
I use a technique taught to me by a former race bike wrench that works:
Do a 'chop' after running the bike for bit at the RPM desired (if you run
the bike and then let it idle, the plug will indicate how it us running
at idle), which means kill the ignition, pull in the clutch, and coast
to a stop and read the plug. You will see a ring of carbon on the
white insulator surrounding the centre electrode. If the ring is
near the tip of the electrode, the mixture is rich. You want the
ring to be up in the recess, near the upper part (i.e., away from the tip)
of the electrode.
Stan Smith
Date: Mon, 08 Jun 1998 09:04:14 -0700
From: Marty MacLean
John Schmidt wrote:
> Gentlemen, I request that we start a new thread. I have been told
that the
> quality of modern gas, being slightly oxidised, requires a different
> reading of the plugs than circa 1973.
I work at an automotive proving ground out in the middle of nowhere. What we tend to see on plugs these days - except when something has puked - is almost all one shade of white or another. This is generally attributed to the high levels of ethanol found in pump gas. Depending on where you are, you might find a notice on pumps at the station indicating up to 10% ethanol - but what you're buying could have significantly higher percentages of the stuff. Far be it from me to suggest that someone might be tempted to lace gasoline with extra amounts of much less expensive alcohol, but we've seen samples with as much as 30% in it.
What to do about reading your plugs? These days, I haven't a clue.
Marty
Date: Mon, 8 Jun 1998 11:14:53 -0700
From: Tom Davenport
>> Gentlemen, I request that we start a new thread. I have been told
that the
>> quality of modern gas, being slightly oxidised, requires a different
>> reading of the plugs than circa 1973.
>
>I work at an automotive proving ground out in the middle of nowhere.
>What we tend to see on plugs these days - except when something has
>puked - is almost all one shade of white or another.
[Snip]
My experience has been exactly the same as far as unhelpful, unreadable plug coloration's go; in California we have a delightful (hopefully soon to be gone) oxidiser in the fuel called MTBE. It is said to be a toxic waste product from another refinery process, which the refiners have cleverly scammed the Calif Air Resources Board into allowing/requiring in our fuel at a rate of 11% (This stuff migrates in water systems and is HIGHLY toxic), thus allowing them to actually _sell_ the stuff rather than having to pay to dispose of it.
No one here or on other MC Lists has given much 'ink' to questioning to what degree these varying quantities of additives change jetting requirements. That certainly entered my mind, and stayed, since my XT500 Yam stuck a piston hard last fall while riding on a cold morning at less than a brutal pace; the motor had no previous jetting problems or mods to airbox, muffler, etc., which would have necessitated fatter jetting, and it had run in a stable fashion for many years..... Until MTBE??
Adding significant quantities of alcohol's to gasoline surely must require jetting changes..... have any of you ever read the pertinent sections in Irving's _Tuning For Speed_ (if memory serves, that was the one) regarding main jet sizes for use with alcohol and other exotic fuels? I bet Vern has, for one.
Lemme tell ya, an AMAL 600 is a pretty big jet, but a 1200 and a 1400 are _really_ impressive!
Tom Davenport
Perpetrator of The Phantom Oiler
Date: Tue, 9 Jun 1998 08:20:46 -0400
From: Allan Johnson
Dear Brit-Iron,
For certain, trying to read spark plugs with unleaded higher octane fuels containing alcohol's and/or MTBE (methyl tert. butyl ether - a methanol derivative) is more difficult than with the old leaded racing fuels. The colours are fainter and the light brown "fuel ring" of correct mixture is more easily obscured by black carbon from throttle "back-off". Still, the same basic reading indicators apply.
A couple of tuning points with fuels doped with alcohol and/or MTBE as opposed to TEL (lead) should be mentioned. Since these oxygenated fuels have more chemically available oxygen than a leaded or aromatic doped fuel of the same octane, they run leaner. This is not a problem in your fuel injected car, where the computer adjusts mixture for you. But in an older carburetted engine (= Brit-bike) you can get more power (and safety from seizure) by going to a richer mixture with an oxygenated unleaded fuel as opposed to a leaded or low (unleaded) conventional fuel.
Also, the oxygenated fuel, since it uses less in the way of combustion-slowing additives (such as aromatics or lead) can be set up with less ignition advance, especially on older engines. This can often be seen on manual ignition control Brit-bikes which will be seen to run "better" with slightly less than "full" advance on the lever.
When working with fuels containing MTBE, good ventilation is necessary due to its "etherish" and disagreeable odour. In the old days, using leaded or aromatic fuels, we should have been using good ventilation too, but since they did not have the odour, we didn't know and the fuel companies had convinced themselves that lead was OK. (It wasn't.)
Allan Johnson
Date: Wed, 10 Jun 1998 21:04:12 -0400
From: Jeff Bean
I couldn't stand it any longer...I called Bosch Technical support. The
drill is this:
W= 14mm threads
5, 6, 7 etc is the heat range higher the number the hotter the plug
R= resistor
D= 3/4" projected tip
C= copper plated electrode
S= silver plated electrode
1= "thin" wire electrode
0= Nickel plated tip
They (technical) prefer to spec plugs according to application,
not on a "crossover" to competitors plug basis.
Interestingly they "spec" a 750 Commando with the W5DC. The 850 Commando is "speced" with the WR6DP.
However in those heat ranges the options are as follows:
W5D
W5DC
W5D-1
W5PO
W6DC
W6DS
W6DP-0
WR6DP
Interestingly, the guy finally admitted the "best" plug they make
is the W6DP-0 which was "developed" for use on 911 Porsches that he described
as having high compression and chronic fouling problems.
Sounded like just what I needed until he told me they ran $28.00 each.
That's all folks!!!!
bucbean
70 Commando, one fouling mother!
Date: Thu, 11 Jun 1998 09:08:56 EDT
From: John Magyar
In a message dated 98-06-10 21:01:05 EDT, you write:
>I couldn't stand it any longer...I called Bosch Technical support.
The drill is this:
[Snip]
Since the above lists do not define the code letter "P", does the code
letter
"P" stand for platinum?
John Magyar
Date: Thu, 11 Jun 1998 08:33:51 -0500
From: Colin Sharpe
There seems to be a fair amount of discussion on the merits and faults
of plugs from different manufacturers. Many years ago, when I was
a member of the Cambridge branch of NOC, we had a presentation given by
a guy from Champion, and I can remember that it was very interesting. The
Champion man was asked by one of the members why it was that his company's
plugs fouled up more quickly than a certain JapANESE plug. The reply was
that the bike was probably running too rich. Apparently the equivalents
between the different makers vary slightly, and Champion tend on the cool
side, figuring that a fouled plug is better than a
holed piston. Since Norton's used Champions when the bikes were new,
and they performed ok., I can only suggest that if your bike is set up
correctly, and nothing in the ignition system is bad, a Champion should
be good.
English.
Date: Thu, 11 Jun 1998 07:37:11 -0700
From: Gary Slabaugh
Colin Sharpe wrote:
> I can only suggest that if your bike is set up correctly, and
> nothing in the ignition system is bad, a Champion should be good.
I agree with the above. I have been using nothing but Champion N7YC's
on a 750 Combat roadster, 850 Interstate, and also my racebike for longer
than I can remember and have never had plug fouling problems. All are Boyer
equipped and have various types of ignition coils installed with plain
non resister type plug wires.
--
Gary Slabaugh Tucson, Arizona
30.4 Plug Gaps with Electronic Ignition.
Date: Mon, 29 Jun 1998 07:30:22 -0700
From: Frank Snively
Jack Ballard asked the list:
> A couple of times in the recent past, I believe someone has mentioned
the
> figure .035" as a proper gap for spark plugs when using electronic
> ignition. If this is true, does this hold true across the board
regardless
> of bike type, ignition brand, etc? I have electronic ignition
on three
> different bikes; Moto Witt on a Laverda, Boyer on a Norton and Dyna
3 on a
> Guzzi. I'm wondering if all three should be set at .035" or
not.
First, note that the traditional British spelling is "sparking plug". Did that terminology die when plugs which could be disassembled for cleaning disappeared? I dunno.
Anyhow, to the subject at hand:
The 35 thou gap setting is a reasonable starting point with automotive
type ignition. (Well, I suppose 0,9mm would be a better measure in most
of the world..) However, it is hardly universal, especially for electronic
ignition. The service manual for my Ducati 907IE says 0,5 to 0,6
mm - did they decide to stick to small coils and gaps when they went to
electronic ignition components? On the other hand, the manual for
my BMW oilhead says 0,9mm just as has been recommended elsewhere.
I can't pretend to be an expert on this, and can only quote hearsay from performance engine tuners who seem to know their stuff, and from essays written by Gordon Jennings, who would no doubt would also consider himself an expert engine tuner. Basically, the longer the spark length the better. The upper limit is set by ability to break down the gap under worst-case conditions, i.e. full throttle at low rpm, when the cylinder pressure is highest. Of course that assumes the ignition wiring is dry or at least silicone grease coated, and free from cracks, etc. and that the coil has no internal miseries.
It's easy enough to try different gap settings, at least if you aren't riding a fully plastic-encapsulated Made in Japan crotch rocket - or a Paso faired Ducati. It needn't be expensive, either, since the crushable spark(ing) plug gaskets can be re-used if they aren't tightened too enthusiastically. With clean threads and a dab of lubricant, it's adequate to go finger tight followed by 1/6 to 1/4 turn. Run 5 to 10 miles to get the engine hot and do a few full throttle runs to verify absence of any miss. Let the engine cool enough to remove the plugs and change the gap, then repeat.
Assuming you find a reasonable maximum gap, set the plugs about 0,1mm narrower (that's 0.004" for us "Murricans) to allow for erosion, wear, and general cussedness of mechanical things.
Thanks for bearing with me.
Frank Snively
who loves the Cummins diesel engine in his Dodge truck - no *!!*#!
plugs.
Date: Sat, 29 Aug 1998 09:43:51 +0000
From: neoludd
delwilli poses the question: wotinell are folks using for a plug gap, as his shop manual sez .020 & his Haynes sez .025.
To recount my own questions about this: I was casting about for more "powerful" coils, to open the gap & thus expose more of the F/A mix to the flame kernal, getting better flame propagation. (I'm running .027 over Bosch platinum's now, Rita, stock Lucas coils (tho one is the red anodised hi perf unit) Anyhow, our Phillip- w/o whom I doubt Id EVER have been able to time the Tridents camshafts- advised me on coil selection but questioned why Id want to open the plug gap wider, which set me back a bit, thinking I had fallen prey to us 'mericans legendary gullibility. (Half the population was hiding under their beds when they were told that "Sandinista tanks were three days from Brownsville, Texas", to name one minor, tho typical example) Anyhow, I got one off list very well written response to say that in this case, as in so many others, "bigger is better". But there wasn't much more of a debate than that.
So, in answer to Comrade Delwilli: ensure the wires are up to snuff, and open the gap to .027. If it misfires under load, close gap. If it doesn't misfire, try .030. Which is what I'm going to try today....
Prof Von Mutt,