YeeHAw!! A sparkplug post!!!

[canyncarvr]

(Words Of Wisdom)
Using the search function on NGK's website, I got no hit when I queried for projected reach plugs. So I asked NGK about it (like, 'Do you make either/both -EV or -EVX plugs in the projected reach style?')

I told them the application was an '00 KDX 200 2-stroke single cylinder.

They said:

It is highly recommended that you don't use a projected style spark plug in your application. These bikes are prone to detonation and vibration and you would be exposing the spark plug to thermal and mechanical shock. The results could be spark plug breakage and internal damage to the engine. If this is a fouling issue your having I would suggest jetting the bike to the spark plug.

If you want to use a projected spark plug then use a BPR8EVX or
BPR8ES and use at your own risk.

Sincerely,
Jon MacQuarrie
Technical Customer Service Representative
jmacquarrie@ngksparkplugs.com
(248) 926-6900 ext 248

Something for youse guys with those 225 pingy big bores to keep in mind? ;) ..mac?

Kinda makes the projected nose plugs sound a bit paltry?

***edit***
Another warning..repeating mostly the above..but read and heed!!!

From NGK:

Use at your own risk. These spark plugs come across my desk everyday severely damaged and requests for complete engine rebuilds. NGK nor the manufacture will help you in anyway if this happens to you. We do extensive testing so we know what should be in this bike and the spark plug that is recommended is the correct plug.

(emphasis mine)

 

[Mac]

When I diagnosed my pinging problem I was using a BR8ES only after I solved the problem did I try a BPR7ES.

The bike runs really crisp with the BPR7ES but I do get a ping or two when I let off the throttle. I assume that when I let off the throttle after a hard run the airflow through the cylinder reduces and the plug heats up just enough to give me a ping.

I may try putting the BR8ES or BR8EG back in now that my jetting is good and see if that helps.

Thanks for the info.

 

[canyncarvr]

?? A BP7 is like a step and 1/2 HOTTER than the B8.

A '7' being on the warm side of things, a 7+ isn't going to make things any better if detonation is ANY problem at all.

Yeah...it's usually a mixture thing that leads to detonation (too lean), but in cases where the static compression ratio is just plain too much for the fuel, it won't matter WHAT plug you use. You can make it WORSE with a wrong plug, but you're not going to make it better until you change fuel.

....or change your static ratio.

Which brings use back to....wonder what YOURS is? Sure would like to know the volume of your head compared say...to BrusH's.

Overall, still happy with the big bore?

 

[Jim Crenca]

CC,

So what plug are you using; I've been happy with a B8EG but have not done any research in this area.

 

[Mac]

Yea I know it's a hot plug but I figured since I'm running high octane I could get away with it and the throttle response is noticably better BUT that closed throttle "ping" has me worried and thats with a CCN-4. Next trip out I'm throwing the BR8EG back in.

"Overall, still happy with the big bore?"--> YES, the bike absolutly rips on top and I can still putt up the tricky stuff when necessary.

I think maybe the RB carb mod may help with some of my jetting issues because I seem to have lean and rich spots below 1/4 throttle depending on how I ride. Main is OK, I run a 152(summer) with no pinging at sustained WOT thanks to Klotz Hitrate.

 

[canyncarvr]

Jim:
B8EG.

Works OK, but could stand some fine tuning. My bike jetting sequences have all been with a '7' plug, due largely to the 'general knowledge' that a '7' is a more correct heat range for the kdx.

I've wondered about the 'general knowledge' part of that. You get into a tail chasing mode if you jet to the plug....and it's the wrong plug! Knowing the air/fuel ratio is the way to know you're jetted correctly, then plug to match THAT, not the opposite way 'round.

...but, the AF ratio isn't a known issue.

That, and jetting to a too cold plug is a good way to stick something, cuz you'll be too lean. Makes a good case for jetting by the seat of your pants!!

I asked once in the hi-performance forum about the determination of the 'correct' choice of heat range for any bike. Obviously, plug color doesn't have anything to do with whether the heat range is correct or not. The post got transferred to the kdx forum with some dings along the line of 'learn how to read a plug.' The whole point was wholly missed.

I'm coming around to the idea of the '8' being the plug to run, and jet to IT instead of a '7'.

The fine wire of the 'G' series helps matters. Before I stock up on BR8EVs or VXs, though, (an even finer electrode, made of precious metals and of course, more $$ !) I wanted some more input from injuneers of the product.

Yeah. The 'G' series is fine, works and all. I just need to dink with sumpin'. Not doing any riding with the woods closed 'til it rains.......:(

 

[BucKat]

Some pleasant plug reading.

http://www.strappe.com/plugs.html
http://www.atlanticjetsports.com/_techtalk/00000005.htm
http://www.tsrsoftware.com/images/sparkplug.gif

Buckat

 

[BucKat]

pay particular attention to the last site.

Buckat

 

[canyncarvr]

Buckat:
Yeah..seen these. Courtesy of you in the first place, I believe.

'..medium brown approx. 1/16" up..'

and...
'If you think about it you'll realize that the only color you can get from an air/fuel mixture is the color of soot.

These statements from two different sources.

It's disconcerting to read the disagreement on such an important engine tuning issue.

I take exception to the, 'If you think about it...' statement. No amount of thinking (on my part anyway) gets me to any such conclusion.

Anyway...the point of the post isn't plug color or how to check it.

Still, it's good to have several references in one place to some 'pleasant plug reading'!! Thanks!!

 

[Jim Crenca]

CC,

I remember that post about sparkplug heat range selection and agree that it got so convoluted as everyone wanted to contribute, but none had a clue for determining the answer; instead all the experts talked up a storm on how to read a plug. As you may recall, I had a similar post in Advance Tech. that took a different approach. My thought (which was later proved too costly) was to forget about reading color, but determine jetting (and plug selection) by using air/fuel ratio as the guide (with 14.5:1 being the accepted standard). I know that my friends and I had great tuning performance gains using exhaust temp measurements in drag cars & cylinder head temp measurements in 4 stroke go karts (also OK results using exhaust gas temp in 2 stroke go karts). This coupled with altitude, temperature, & barometric pressure allowed us to dial in an engine quickly, effeciently, & safely regardless of the track or the weather (relative to the competition). The summation of Rich Rohrich's thoughts on this were as follows:
* Dirt bikes don't usually run full time, WOT (unless they are flat track bikes or desert racers)
* EGT or CHT gauges (or the so called air ratio meters) for cars don't react quickly, or accurately enough
* O2 sensors won't last or read accurately in a 2 stroke (unless they are very expensive
* And, the only way to accurately tune a 2 stroke with electronics is with a spark detonation counter developed by Honda and presented in a SAE paper; it used a microprocessor & propietary software)
I think that fuel injection may change all this in the future, and, I don't know a scientific way to select plug heat range either! I do know that Kawasaki specs a B9 plug for my 94 KDX and that the B8 works much better and has proven to be a good choice even when jetting is on the lean side.

Jim
PS. I had forgotten that Gordon Jennings wrote great articles although his "plug selection" advice was more like what NOT to use IMO.