Spark plug question

[Plowboy]

 Every resource I have at my disposal calls for an R6254E-9 NGK plug for my '92 KX250. The bike came to me with a B8ES in it, and although it's running on the B8ES, am I missing(hurting) something by using the cheaper plug?

 Why does the '92-'93 call for the more expensive plug?

[dmstarr]

If the bike runs good with no overheating, and the plug looks good you should be fine. I don't have a cross reference handy, but I know most of the 90's model KXs came with a B8ES plugs.

FWIW, the minis call for a 105 racing plug, and I always use BR9ES.

[Plowboy]

 Everything seems to be okay with the B8ES that's in it, so I don't see any point paying 3+times as much for the special plug myself.

 The 6254 looks very different on NGK's website though. Here's a pic.

[FuriouSly]

Everything seems to be okay with the B8ES that's in it, so I don't see any point paying 3+times as much for the special plug myself. The 6254 looks very different on NGK's website though. Here's a pic.

The 6254 has a fine wire electrode, much thinner that the ES.  ES standard plug is "old" tech....

R6254E-9 = Racing plug, 14mm, 3/4" reach, 13/16" hex, gasket seat, non-resistor, nickel alloy fine wire center and ground electrodes, solid terminal, .060" gap

BR9EG = Racing plug, 14mm, 3/4" reach, 13/16" hex, gasket seat, resistor, fine wire(1.3mm) nickel center electrode, traditional ground electrode, solid terminal

6254 is a nice plug, very specific.  Non Resistor plug with a specific gap of .060"..... interesting.  Has a nickel alloy ground prong too..... nice!

Other than that they are the same spec on size and temp....

Sly

[Plowboy]

 I wonder if I should increase the plug gap on the plug I'm using since the 6254 is .060 and I'm only at .024? Maybe I am missing something in the way of a larger spark/flame "kernel".....but then again with the B8 standard plug more of the spark/flame is exposed than with the 6254.

 Very interesting.

[FuriouSly]

I wonder if I should increase the plug gap on the plug I'm using since the 6254 is .060 and I'm only at .024?

Spec on 1992-1993 KX250 spark gap is .9 or .036...  pretty much prior and after those years the gap is .7 or .028...

Maybe I am missing something in the way of a larger spark/flame "kernel".....but then again with the B8 standard plug more of the spark/flame is exposed than with the 6254.

If your bike is stock with an older top-end then you wont really notice a ton of a difference between plug grades.  Actually it becomes harder to foul the ES because it has allot more electrode(s) surface area.

But in higher compression/modded bikes it becomes the opposite.  You will need a higher quality plug EG/EV/EIX to actually not foul (understand what fouling is??) and produce the proper spark needed.....of course I am not an expert and these are my opinions only...

ES/EG plugs are great for putt putt riders, lawnmowers, and weed whackerzzz.... hehehehe

Sly