Favorite spark plug?

[MtnEX]

Does everyone run the NGK DPR8Z... or is there something else you like better?

[Wheelie]

Stick with NGK.

DPR8Z for stock engines.

IMO a DPR9Z is a good choice for modded engines.

[BossHogg420]

the 9z runs great in my stock motor!

[NacsMXer]

Originally posted by Wheelie
Stick with NGK.

DPR8Z for stock engines.

IMO a DPR9Z is a good choice for modded engines.

Word. The DPR9Z helps prevent excessive heat when heat-adding mods such as bigger bores, higher compression, timing keys, and many others are introduced. I believe the manual also recommends it for stock motors running at sustained high speeds. So basically if you run your motor hot, you want a colder plug.

I run the DPR9Z religiously. Though I have a few DPR8Z plugs laying around from when my motor was stock that are pretty much worthless to me now :ermm:

No matter what, NGK is the way to go.

[SteveWR450F]

My girlfriend quad has stock motor. Just White Bros e2 pipe.

I had extra race gas and filled her tank 50-50 with race gas and premium pump gas. Motor ran really good. Started very easy.

However, have 2 rides the plug when bad. Really hot and black, not tan color.

If she continues to use race gas, should she switch to the DPR9Z plug instead? Help or hurt the situation?

[NacsMXer]

Originally posted by SteveWR450F
My girlfriend quad has stock motor. Just White Bros e2 pipe.

I had extra race gas and filled her tank 50-50 with race gas and premium pump gas. Motor ran really good. Started very easy.

However, have 2 rides the plug when bad. Really hot and black, not tan color.

If she continues to use race gas, should she switch to the DPR9Z plug instead? Help or hurt the situation?

Kind of a waste of race gas to run in a stock motor IMO, but the race fuel actually wouldn't burn any hotter. You don't need to switch to a colder plug on that motor.

[lilyamaharacer4]

Originally posted by NacsMXer
Kind of a waste of race gas to run in a stock motor IMO, but the race fuel actually wouldn't burn any hotter. You don't need to switch to a colder plug on that motor.

+1 Race gas actually burns cooler and slower than regular gas so that was not on a cause of the race gas.

[SteveWR450F]

Thats what I recall too - more octane = more efficient explosion - but it was just strange that it was that hot. Mainly just cruising on fire roads that day.

[MtnEX]

I'm surprised nobody really uses a different spark plug.

I figured several would use Denso, E-3, Autolite Extreme Sport, Champion PowerSport, Bosch, etc.

[isotope]

i've only ran NGK, bought my quad and the guy include a box of about 12 NGK's,,,been 5 years and i think i still have one new one in my "tool tube" on the 300ex

[MtnEX]

What NGK 8Z plugs I did get over the summer... I guess I was just lucky and got the last of an item nobody stocks anymore. I can't even get them now unless I order them.... unless I wanted to try the stealership to see if they have any.


I can get the Champion PowerSport plug for it right off the shelf at Wal-Mart no less... and I had gotten in the habit of using them for plug readings because you can see well down between the shell and the center electrode... because the electrode is small.


But I swear, this method is not working out for me on the 400EX. I don't know if the last NGK I had was bad or if the Champion is that much different of a plug... (should not be) ... The NGK dry fouls and the Champion is light colored.

Can't tell if it's jetting or plug heat range.

It looks like plug heat range or a bad NGK to me.
But if it is, it doesn't look like the Champion is too hot really.

the champion plug sucks!!!

i had to use one in a 300ex quite a few years back...the dang thing backed out, or loosened, twice on me...i bought 2 at the time and i still have the second one sitting in the junk bin in the garage...


and the bike never ran correctly with it...

[krt400ex]

Originally posted by Wheelie
Stick with NGK.

DPR8Z for stock engines.

IMO a DPR9Z is a good choice for modded engines.


i run NGK, im wondering why you say to go with a colder plug for a modded engine?

[MtnEX]

Originally posted by speedyquad
the champion plug sucks!!!

i had to use one in a 300ex quite a few years back...the dang thing backed out, or loosened, twice on me...i bought 2 at the time and i still have the second one sitting in the junk bin in the garage...


and the bike never ran correctly with it...

Well, I can't say I have ever been a fan of Champion plugs.

I only started buying the PowerSports plugs for tuning runs, because it's so much easier to see down to the base of the center electrode. That got me to try them just to run to check jetting.

However, I can't say these are a bad plug because I have ended up using them some along the way, and haven't had bad results. Not even in 2 strokes. I haven't had bad results with the 400EX either... just strange results compared to the last NGK I had for it... which could be a bad plug.

[Wheelie]

Originally posted by krt400ex
i run NGK, im wondering why you say to go with a colder plug for a modded engine?

Higher compression equals more heat. The cooler plug helps to offset combustion chamber temps.

[krt400ex]

Originally posted by Wheelie
Higher compression equals more heat. The cooler plug helps to offset combustion chamber temps.

wow, you think i coulda figured that out :o :rolleyes:

[hypersnyper6947]

Originally posted by krt400ex
wow, you think i coulda figured that out :o :rolleyes:

LMAO

Do you guys know if the 9z will work on a raptor 660 also, im going to make the switch and probably have my buddies switch too.