Spark Plug gap?

[Badmammajamma]

Quick question, do atv spark plugs come pre-gapped? I changed mine a few days ago on my 400 and didn't even think about the gapping until now. Used a NGK plug if it makes a difference.

[250exkid]

some might but i no i just bought one and it was Not gaped so yea chances are that it isnt ... so take it out and gap it and you should be fine

i always check...but i bought 10 ngk plugs for a 400ex one time and they were all gapped correctly

[Badmammajamma]

K now my next question. What should the gap be set to?

.024-.028

[Badmammajamma]

Thanks:)

[250exkid]

wow wo wo .028! WOW the dealer ship by me said like .020-.024

[GPracer2500]

Originally posted by Badmammajamma
....Used a NGK plug if it makes a difference.

It does make a difference. All NGK plugs I'm aware of come pre-gapped with a "standard" gap deemed appropriate for that plug (0.7mm or .028" in the case of the 400EX's DPR8Z). In the vast majority of cases I've encountered, engine manufactures will recommend whatever gap is "standard" for that plug. Basically, if you use the correct NGK plug number you'll get the correct gap (but it never hurts to check the manual to double check the spec). Like speedyquad, I sometimes check my NGK plugs anyway but I do that less and less because they are always correct.

Not every plug manufacture is like that though. Some manufactures may set all there plugs to the same gap and require you to correctly gap them. Splitfire (not a good plug IMO) is like that but these days I think most mainstream plug manufactures pre-gap their plugs.

With NGK plugs, if the engine calls for a gap larger than "standard" for that plug, NGK will often make a different plug that is identical except for the gap. You can identify these plugs because there will be a number at the end of the plug identification code. The number is the gap in tenths of a millimeter. For example, an NGK BR8ES would be manufactured with a 0.6mm gap (the standard gap for that plug). If an engine called for a BR8ES11, the plug would be identical except the manufactured gap would be 1.1mm instead of 0.6mm. You could use a BR8ES in an engine that called for a BR8ES11 but you'd have to gap it yourself.

[JOEX]

Nice to see you back GPracer:)

I have an example on why it's a good idea to check the gap. Awhile back I was doing a tune up on my V6 truck. Asked for all the parts over the counter, got handed a 4 pack + two individual spark plugs. Checked the gap on the two individual ones and set them to where they were supposed to be continued on and the other four were already correctly gapped. That got me thinking why the first two needed to be adjusted. Looked at the boxes and sure enough the two singles were the wrong plug.

Moral......Make sure you have the correct plug before installing:)

[250exkid]

belive it or not but a genuine honda plug i got free from the dealer was gaped way to big like over like .033