Spark plugs multi ground vs single ground

[wile e]

Quick question, having searched the boards I have not come up with an answer for this.

I went to my local parts store and asked for plugs for my 2002 RR. Having checked his list, he gave me NGK BKR6E plugs. Not paying attention, I grabbed them and left. Now that I've pulled the plugs from my bike, I realized that the ones installed (and recommended by BMW) are multi grounded plugs, whereas the ones mentioned above are not.

How big of a deal is this? Why would a computer system cross reference these plugs when a multi ground is recommended?

As I bought these plugs in the states and am now back overseas, returning is not a possibility. The money lost is not a big deal, however as I was trying to save money by buying the plugs in the states, I would like to use these. Finland is not too kind to wallet.

Thanks.

[philbytx]

Don't worry....they will be fine!!!
Many folks also use single ground Autolite 3923's in their OilHeads as well.

[wile e]

Great, thank you very much.

[challey]

Just to elaborate a bit, it doesn't matter how many ground electrodes are on the plug, the spark only travels to one. As I understand it, on multi-ground plugs as one gets worn or otherwise becomes less than ideal, the spark will jump from the center electrode to the next closest ground, i. e., the one that is now properly gapped. So the only advantage to using multis is that you nearly always have the correct gap setting since there are more correct ones for the spark to "choose".

Charlie

[CycleRob]

I think the multi prong plugs are more marketing than improved function. The spark takes the path of least resistance. A single blue hairline spark. It does NOT jump from each and every electrode at the same time, like you assume it will.

You need only look to racers for the truth. "Indexing" the plugs, or using different thickness washers so the prong's metal support can be rotated less/further so it does NOT shroud or block the incoming fuel mixture is used by the SuperWrenches. When the ground electrode is perpendicular to the intake charge, it's airgap is blown clear and filled by that intake fuel mixture.

Here's the good part. YOU can do just that, to a point, with your Boxer Twin. I place alignment of the electrode's welded post with the plug wrench's extended handle to determine where the electrode base post is after tightening. Just use the nearest hex position that is closest to the handle when inserting the plug into the socket and keep the wrench engaged with the handle unmoved from alignment until the plug is tight. Since the intake charge comes in from the (slight) upper right, the handle ideally should be pointing perpendicular to that or at the 11 O'Clock or 5 O'Clock directions. Either one is OK. If it is off, at 2 O'Clock or 8 O'Clock, switch the sparkplugs and try again. They both will be different. Use the best installed version that minimizes the intake charge shrouding. My bike came out almost perfect perpendicular, just by switching them. Cool.

[iowabeakster]

Holy spark plug instruction.

Rob is this some cruel mechanics practical joke? To see how many guys will run outside check the orientation of their spark plug electrodes?

[towerworker]

Rob is right. I did what he suggested and get better milage, more horsepower and now the women like me better. (they didn't like me at all before)

[CycleRob]

It's not a joke. It's mostly used by racers looking for that extra tenth of a second per lap. In a 20 lap race they are 2 seconds ahead . . . . a huge distance at 140 MPH (225 kph).

Indexing the sparkplugs on a streetbike is reserved for the kind of rider/owner that has a toothbrush in the bike's cleaning kit. If you've ever cleaned the front wheel spokes or behind the footpeg brackets, you know an old toothbrush works best.

.

[towerworker]

Rob--

Just adding some levity. I knew you were right. I've read of that before elsewhere.