plug reading on DL
 

I have a DL50 that runs good but at full throttle it will "blip" a little from time to time. I took the best pic I could of plug to see if any of the gurus here could tell me if I still have some leaning room or about right.
Any suggestions much appreciated. I hope the pic shows enough.

Z

RE: plug reading on DL
 

I'm no guru nor a "spurt" but your plug looks good to me. I've seen/heard some high throtlle "blips" a few times and they always seemed to be voltage related. Make sure your ignition switch, extensions(adequate guage) and connectors are in good shape and haven't been exposed to extreme heat such as being too close to the muffler/cylinder and degrading (melting) the shielding. Check ignition battery voltage with a loaded voltmeter? Have you tried running the motor with battery plugged directly into the EI and by-passing the switch and extensions to see if the "blip" goes away? If you do by-pass the switch to test, make sure you have an alternative way to shut down the engine! ;)

RE: plug reading on DL
 

What is the gap set at? You may also try this in photo. Regards, Capt,n

RE: plug reading on DL
 

I wouldn't touch the needles. That looks just fine.

If those little blips you are referring too are like quick, short "hiccups" in running it's possible that the engine is experiencing a little carbon ball fouling at the spark plug. The "blip" that happens is the plug mis-firing until the carbon ball at the gap is cleared. It's pretty common and if the oil ratios are reasonable there's not a lot you can do about it other than open the plug gap up more. That's not the best idea though.

RE: plug reading on DL
 

Is far as I can judge the picture, the plug loos excellent, but there is no leaning room at full throttle. Your plug body rim is a bit too pale for me to feel comfortable. Try a slightly richer H-needle setting, but be sure to keep track of what you do.
This paleness I think is there can also be due to camera, lighting, type of gas and oil brand, so you may have to go back to your original setting in a hurry.
I would rather look down into the plug body and try to find the little black carbon deposit mixture ring where body meets isolator. If it is there, leave the needle setting alone. If it isn't, open up the main needle.
http://www.prme.nl/forum/images/plugreading.jpg

PS
You may need a maglite and magnigying glass to get a good look.

RE: plug reading on DL
 

good info guys and much appreciated. I will take a look at all your suggestions.

Thanks again

Z

RE: plug reading on DL
 

One other question, the manual says that the idle needle setting will effect high end needle and vice versa, any chance the idle needle could take some leaning and it end the "blips" at full high throttle?

Z

RE: plug reading on DL
 

With your plug colour, blips surely are not due to rich settings, so leaning will not solve them.
Like Pat said, these blips may be caused by plug gap bridging of one kind or another. (lead whiskers or carbon) Lead fouling will not happen in leadfree fuel.
At idle, the idle needle is the only active control. The idle needle supplies about half the fuel that the H-needle does at full throttle, so closing the idle 1/4 turn means the H-needle must be opened about 1/8th turn to compensate.
That also is why the idle mixture must be set before the full throttle mixture, only to be touched again for fine tuning.

RE: plug reading on DL
 

Makes sense, thanks a bunch. I will work with it some more today and see if I can get it dialed in. I had a 1700 4.8 on it. I just changed over to a NOBS 1500 elite 6.0v with a 5.4 regulator. I also did as capt suggested and angled the tip on a brand new CM-6.
Thanks again

Z

RE: plug reading on DL
 

cap'n - this looks almost like those magical "special" electrode shape plugs that are supposed to be better than sliced bread. I'd be real interested in reading any quantitative data/information about what this reworking of electrodes is *known* to have done for an engine's performance.

I've seen things like this done before....the person installs the modified plug, then has to "readjust mixture". Well, the mixture was probably not right in the first place, and the person tweaked the gap through all the screwing around with the plug, and HAD to change things. So they lucked out, adjusted it "better", and decided that the rework of the electrode was the magic cure.

I'm not saying doing what your picture shows doesn't improve something - just wanting actual data to support the benefit of it.

Zman - FWIW, Pe and Pat Roy are the closest to "experts" that I know of on this forum, besides a few others. Your plug looks fine, maybe perhaps just a skosh lean, but what is in the picture doesn't look like a tuning problem.

RE: plug reading on DL
 

Bob,
The sharpening of the electrode provides a stable, hotter spark at a fixed location every time. Electric charges love sharp edges so they can ionize the surrounding gas and make a spark jump.
Whether this provides more power or not remains to be seen. It does however reduce the voltage needed for a spart, and make the spark more consistent. It also increases the available top end rev range, because less capacitor charge is needed (In CDI) or dwell in contact breaker ignitions. That is why pure racing plugs often have a very thin central electrode. For sustained spark energy at high rpm.

RE: plug reading on DL
 

Hellow Bob: The photo in post # 3 has some data on source. High Flight V1-2-15 in upper left corner. I have done the mod only to mag engines that have kinda weak spark to begin with. Boy they start a lot better...and the idle speed was a tad higher without adjusting anything. For kicks I set the idle as low as it would run on mag. I had guys say they never seen that paticular engine idle that slow. I am positive it ran better in all respects. It is a lot of messing around to do. I want to warn guys that do this. Make sure no metal filings are left on plug. Glade to share with all...just like you like to share. Tis a good thing! Best Regards Capt,n;)

RE: plug reading on DL
 

Pe and Cap'n - I am always open to new stuff, when known to be valid. This seems to be the case on squaring of the electrodes. I apologize if I sounded "doubting", but I tend to be cynical by default.

I"ll go sharpen mine, now!
Thanks again.

RE: plug reading on DL
 

Not a problem...We am getting ready to go on a little vacation. If I could find the "rest of the story" like Paul Harvey says...I would post more on that spark plug mod...just do not have time right now! Best Regards capt,n

RE: plug reading on DL
 

Thanks captin. I printed the pic and I am going to try it on my G26.

RE: plug reading on DL
 

No problem Bob. It just works in producing a healthy spark.

RE: plug reading on DL
 

Pe ( and cap'n, if you're around) - I checked my NIB NGK CM6's and BPRMR6's, and they were nicely-squared, although not "sharp" cornered, but sharper than other brands I had. Interesting learning, here. Thanks!

RE: plug reading on DL
 

The center post of some spark plugs have a spline look to them. That spline makes for edges...that can help the spark jump the gap! Capt,n;)

RE: plug reading on DL
 

Here is the plug of my current engine under test. The plug body is on the verge of loosing it's black, sooty, but not oily.
The central isolator is clean with brown tip, and black mixture ring way down (see arrow)
Only the mass electrode is sharpened.

I hope some hawkeye will see the problem with this engine??

RE: plug reading on DL
 

Gonna go out on a limb say "low oil ratio"

RE: plug reading on DL
 

oil ratio is 2.5% according to factory wishes. The oil permits a 2% ratio.
Hint: take a close look at the colour of the earth electrode.

RE: plug reading on DL
 

PR your earth electrode looks like it's running hot to me which suggests maybe a cooling issue as the mixture looks OK to me[sm=71_71.gif]

RE: plug reading on DL
 

getting closer.
Ran on test stand, out in the open. Without airspeed, cooling is less and might endanger the engine, but temperatures were monitored, and engine was not allowed to run higher CHT than 205°C peak. Cool-downs in between.

RE: plug reading on DL
 

Purely a guess now how about a leak on the plug seat?

RE: plug reading on DL
 

excessive ignition advance.