Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: singhg5 on May 10, 2011, 03:45:56 pm
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In UCE EFI bikes, different kinds of spark plugs have been used, tested, discussed but I had not seen a real comparison of how deep they are inside the cylinder - which will determine the location of spark above the piston. If it is too close to piston, it will act as timing is too advanced and too far away from piston it will feel like the timing is retarded. That can affect the engine performance and likelyhood of piston damage.
UCE EFI bikes are originally fitted with Bosch WD7 DDC4 spark plug with Dual Electrodes which are on either side of the central electrode. Took this picture to compare the lengths of NGK Non-Projected (B8ES) and Projected (BPR 6ES) spark plugs with the Bosch plug.
Non-projected tip is clearly shorter and projected tip is slightly longer than Bosch plug.
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It's not just depth/distance from the piston that matters. You'll notice in the two plugs on the right that the electrode is more exposed.
Found this:
http://www.ngk.com.au/sparkplug_tech.php
It explains many of the common aspects of spark plugs including projection:
"A projected spark plug protrudes into the combustion chamber further and provides higher ignitability and improved performance. Simply this can be understood by representing the combustion chamber as a circle. A projected spark plug in effect produces a spark in the middle of the circle (or combustion chamber) allowing for an even flame spread. Conversely, a non-projected spark plug means the flame spread is not even."
It also explains the precious metal electrode nicely. Since it has a higher melting point it can be narrower and again, gives you a cleaner, more precise spark resulting in better performance, whiter whites, britghter colors, and world peace :) I think at least one user noted better performance (notably more stable idle IIRC) with a precious metal plug.
Scott
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I pulled my original plug to see how it looked after 1 tank at TPS .724
My NGKBR6ES looks like the right side picture of the middle two optimal heat range:
http://www.ngk.com.au/sparkplug_tech.php#
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It also explains the precious metal electrode nicely. Since it has a higher melting point it can be narrower and again, gives you a cleaner, more precise spark resulting in better performance, whiter whites, britghter colors, and world peace :) I think at least one user noted better performance (notably more stable idle IIRC) with a precious metal plug.
Scott
Aahh if only that were true.
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I said one user, not you ;)
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I have put in a Iridium plug in my C5 about 3000 klm's back and it works fine. It supposedly last about 100,000klm's and by that time I'll be to old to ride.
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Hey Folks,
I run Bosch dual electrode plugs in my Enfield and my 79" Harley Shovelhead. I also run dual electrode plugs in my Cessna 150. As far as I know, all air cooled aircraft engines run dual electrode plugs for reliability. That's good enough reason for me to use them in my motorcycles. Just my opinion !
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Recapping my experience:
New bike 0-300 miles Bosch WD7 DDC4 - occasional stalling on idle, bit of rough starting (probably just a "tight" engine), but electrode color looked good.
300-600 miles Iridium NGK BR8EIX - synthetic oil, great starting and idle, and electrode came out as expected with a thin layer of fluffy carbon.
600-800+ miles Iridium NGK BPR6EIX - another synthetic oil change, great idle and running, starting is a bit flaky but no stalls........I can almost feel slightly better acceleration (or maybe the engine is simply more broken in) :)
Great bike....snow is gone...85 degrees outside.....
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Hey Folks,
I run Bosch dual electrode plugs in my Enfield and my 79" Harley Shovelhead. I also run dual electrode plugs in my Cessna 150. As far as I know, all air cooled aircraft engines run dual electrode plugs for reliability. That's good enough reason for me to use them in my motorcycles. Just my opinion !
And a GOOD opinion it is! The REASON that these particular plugs were chosen is the fact that the flame kernel is not occluded by the ground electrode - the same reason they are used in aircraft engines, where a single misfire could have dramatic consequences. Using a projected tip plug WILL get the flame kernel started down in the "sweet spot" of the reactible gas in the chamber (Henry Yunick patented them for just that reason ...) I have found that if the heat range is correct for the mixture that you are running, the single electrode plugs are just fine. The ONLY difference that i found was in the hot starting - it usually took a couple more cranks (literally two ...) to fire the lean-ass mixture in the hole with the single electrode plug .... but that's ALL.
Jjoe 226 has it right with his ..... they are PERFECT as for what they should be .... Of course the ULTIMATE plug would be a surface gap one ..... ::)
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Scooter Bob is showing his deeply technical side. ;D ;D ;D
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I said one user, not you ;)
I meant world peace, etc.
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;D
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. The ONLY difference that i found was in the hot starting - it usually took a couple more cranks (literally two ...) to fire the lean-ass mixture in the hole with the single electrode plug .... but that's ALL.
Jjoe 226 has it right with his ..... they are PERFECT as for what they should be .... Of course the ULTIMATE plug would be a surface gap one ..... ::)
I figured out my hot starting. Using the kick start, which I normally do, I ease past 1 TDC and the bike fires first kick. Cold start, with "choke", 2 eases and first kick fires. Every time. NGK BR6ES
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Scooter Bob is showing his deeply technical side. ;D ;D ;D
Half a hour ago, I couldn't even SPAIL Muh-Kanick ..... Now I are one! ::) ;) ;D ;D ;D
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Half a hour ago, I couldn't even SPAIL Muh-Kanick ..... Now I are one! ::) ;) ;D ;D ;D
You slept at a Holiday Inn Express last night didn't you?
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Page 49:
http://books.google.com/books?id=x_UDAAAAMBAJ&pg=PA49&lpg=PA49&dq=air+cooled+motorcycle+engine+summer+cooler+spark+plug&source=bl&ots=ZLcvAgiqnB&sig=Xe396bGwNjIvHjSFON8y-ZfE4WQ&hl=en&ei=6TXMTeTFCMXliAL8wfyTBQ&sa=X&oi=book_result&ct=result&resnum=4&sqi=2&ved=0CGAQ6AEwAw#v=onepage&q&f=false
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A few days ago I mentioned on the forum that when I was riding my new G5 at a smooth 45 mph occasionally the engine would mis-fire, like it suddenly wasn't getting a spark. Nothing serious but an annoyance to say the least.
Another member said it was the Indian spark plug the bike comes with so with this in mind I did some digging.
Several posts mentioned the NGK BPR6ES plug so I went to my local auto supply and they had some of them.
After gapping it to .028 I installed it using my torque wrench set to 20 ft/lbs.
Today I rode the same route that I rode when I noticed the misfire and it ran perfectly.
In addition, the falling idle speed and dieing at a stop light has disappeared. If anything the new idle speed is fast enough to make me think about adjusting it down a bit.
So far I'm a happy biker. :)
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Great choice. I saw the same improvements when I went from OEM to NGK plugs.
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+ 1
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(http://i326.photobucket.com/albums/k409/prof_stack/plugs.jpg)
Scroll to the right to see the OEM (rich mix) plug.
I installed the NGK BPR6ES today. With a little grease on the threads it hand tightened smooth as can be. The OEM Bosch R6 plug was rough to get out with ratchet and plug socket.
The black Bosch tip verifies what the dyno test read regarding the air/fuel mixture. Would a hotter plug be a better thing to have in there?
A ride to the dealer and around the area seemed to verify what Arizoni said about the idle being a little higher and not prone to have the motor stall. At $3 a pop, I could change the plug more frequently.
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I've been running that plug for quite a while now, it does very good for me. Get a tube of anti seize compound for your threads it's good stuff.
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Has anyone done dyno tests between the plugs discussed here?
I'm tempted to try the ngk plug because I did have some running issues when I had my free flowing exhaust on from nfield (which Enfield says should have worked fine). I blamed it on the exhaust and a narrow ECU tuning range, but hey, maybe it was the plug!
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I installed the NGK BPR6ES today. With a little grease on the threads it hand tightened smooth as can be. The OEM Bosch R6 plug was rough to get out with ratchet and plug socket.
The black Bosch tip verifies what the dyno test read regarding the air/fuel mixture. Would a hotter plug be a better thing to have in there?
Some greases tend to cook off at temperatures around 250 degree F while some of the special wheel bearing greases can go up to 380 degrees F.
The spark plug in an air cooled engine gets hotter than 250 degrees.
Without knowing exactly which grease you used you could be fine or the grease might cause a removal problem.
The Anti-Seize stuff is good to higher temperatures and it doesn't cost a lot. Next time you buy a spark plug you might want to get a small tube if it.
A little goes a loooooong way.
When your applying Anti-Sieze apply it to the threads only. You want a bare metal to metal contact between the spark plug, the gasket and the cylinder head.
As for the Dyno test, your engine was running at max power and although I have no idea what the computer mapping on a RE is, max power usually requires rich mixtures so I would guess that is what your bike was getting during the test.
Unless you plan on running your bike at its limits I would hold off on getting a hotter spark plug.
Run the new plug for a while and then check its color. I'm betting it's just about right for daily riding.
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Thanks for the tip. I bought some anti-seize stuff today along with another new plug for whenever I change it next. After 110 miles it is starting to get some rich blackness around the sides but okay in the middle. Check out the photo. See what you think. On the right is the OEM Bosch.
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My plug gets black like that round the rim and the first couple of threads, so do the plugs on the other bike. I'm told by those who seem to know that this is fine as long as the business part is a nice tan colour, which it is.
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I get the same. Black on the ring, tip and electrode are tan. All good.
At 6000 miles I just swapped to an NGK BPR6EIX gapped to 0.7mm. Only one ride to work on it so far, seems about the same to me as the OEM Bosch plug. I'll keep y'all posted. Even if it's no better or worse, nice to have alternatives.
Scott
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I noticed a real difference when I fitted that plug last year - much better starting, hot & cold. I also thought the engine ran smoother generally, and certainly idled better.
I've since replaced the standard NGK plugs in the Kawa with Iridiums, but can't say I've noticed any difference.
Could be the stock plug in the Enfield was dodgy......
NGK - good plugs.
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Feels about the same to me so maybe your original plug was dodgey. I'll report more after it's been in a while.
Scott
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Feels about the same to me so maybe your original plug was dodgey. I'll report more after it's been in a while. Scott
The only thing I noticed so far is a more consistent idle with none of the trailing off and stalling stff at a traffic light I was used to with the OEM plug.
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My plug gets black like that round the rim and the first couple of threads, so do the plugs on the other bike. I'm told by those who seem to know that this is fine as long as the business part is a nice tan colour, which it is.
Will, you mean the white part in the middle? I heard it should be a nice light to medium tan color.
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I'm sure that the ceramic center electrode support is what he is speaking of and yes, a very light tan to a darker tan is good.
Before installing the NGK plug in my bike I had noticed not only some stalling at stop lights but while just cruising along at 45 mph there would be a mis-fire that lasted maybe 1/2 - 3/4 of a second. This was happening about every 1/2 mile.
After replacing the plug I have never had another mis-fire like that. :)
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Ok thanks.. Looks like I'll have to try one of these plugs too! Any negatives on the swap?
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As I recall, the NGK BPR6ES came gapped at .030 rather than the .028 recommended in the UCE manual. No problem as this NGK plug has an easily bent electrode.
It also has a screw on cap that I removed to allow it to mate with the existing high tension wire.
You probably already know it is a good thing to apply some dielectric grease to the ceramic insulator above the steel body and some anti-seize on the plugs threads is highly recommended. Don't get this anti-seize on the gasketed surface as it does not conduct electricity well.
As I recall, the torque for the spark plug is 20 lb/ft.
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@ Sub - Yes that's what I meant. And the electrode.
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FWIW, I changed to a NGK BPR6ES and many of the hiccuping and off-on throttle quibbles are gone.. Its definitely a noticeable improvement on my bike (air intake and efi exhaust). The bike also feels a bit smoother, and maybe even a bit quicker, although at the HP of this bike, who can really tell. :)
Here is my old plug, does it look ok? I'm including two pics because its hard to capture the tip color.. its light in color.. maybe a shade towards brown/gray. Am I a bit lean?
(http://farm6.static.flickr.com/5108/5887173577_b826e0e0c1.jpg)
(http://farm6.static.flickr.com/5108/5887176081_e8d4379244.jpg)
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Looks lean to me. Of course with the air box mod youve made with the exhaust you were running, would be suprised if you werent a little lean. I will be looking forward to seeing the NGK after 300 miles or so, glad to hear your having the same good results with them that I and most who installed them are experencing.
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Looks lean to me. Of course with the air box mod youve made with the exhaust you were running, would be suprised if you werent a little lean. I will be looking forward to seeing the NGK after 300 miles or so, glad to hear your having the same good results with them that I and most who installed them are experencing.
+1
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... Of course the ULTIMATE plug would be a surface gap one .....
Do they still make those things. They worked pretty miserably in anything I ever saw them in. '70s Kawasakis, specifically. They always struck me that they were too cold. The Kwackers ran much better on conventional plugs.
The reason airplanes use dual electrode plugs is because the comparatively low voltage of the circa 1920 magneto ignition. They won't knock off minor soot-type fouling, so they have to bypass it...hopefully. Any modern EFI ignition supplies much more voltage that can blow past minor fouling attempts in the cylinder.
P.Schraub...Haven't you ever had to clear a fouled plug in your Cessna One-Filthy?
Bare