Spark Plugs for 400EX

[flyin_high]

the size spark plug in my bike right now is a DPR8Z, i wouldnt mind running a splitfire plug in it or even a hotter burning plug to burn off the excess gas thats making my plug foul up, any ideas on a number to match a splitfire plug or evn a hotter burning plug that i could get???

[YZROOSTINYA]

jet your quad correctly and you wont foul plugs. a hotter plug in a incorrect jetted motor just causes more problems.

splitfires are a waste of money

[flyin_high]

i ahve my bike jetted by dynojet, got a 160 jet in it because thats what it calls for for my altitude, im in canada by the way, but it still fouls plugs, could i just mess round with my fuel mixture screw maybe, it has to be something simple why its doing it tho i cant se it being anything major. something just hasta be adjusted right or something, somethings out of wack but i cant figure it out what it is, the plug after i put it in my bike and run it for about 3 days, and take it back out, theres so much black carbon on it that it fouls the plug up and just plainly pisses me off, just a pain in the *** havign to change plugs all the time.

[YZROOSTINYA]

your main is too large

I have a 155 in mine and it is perfect. about 1500 feet.

dyno jets are also bigger then stock. a 160 dynojet is like a 165 stock. I hae a 155 stock

try going down to a 155. make sure you air filter is clean.

[flyin_high]

ok, so i have the either 160 or 165 jet in my bike right now, so if i take that jet out and switch it with the 155 jet will i notice the diffrence in power or anything from the jet i have in it now???

[GoOn3]

what type of oil are you running? When I run synthetic, I seem to foul plugs. When I run semi-synthetic or non synthetic I have no fouling problems.

[UglyMotha™]

Originally posted by GoOn3
what type of oil are you running? When I run synthetic, I seem to foul plugs. When I run semi-synthetic or non synthetic I have no fouling problems.



is this some kind of joke :huh


if you got oiling fouling your plugs your motor is in due of a serious rebuild :huh

are you going back & forth from synthetic to non synthetic?? :huh :eek2: :huh :eek2:

[cals400ex]

the 155 will probally give more power than the 165 if i had to guess. also, i bet your fouling plugs because your pilot jet is too small. i would get a 40 or 42 pilot jet and that should solve your problems with the plug fouling when trying to start it. if you refuse to buy a new pilot, you could try turning the fuel skrew 3 turns out from lightly seated and see if that does anything.

[dariusld]

[QUOTE]Originally posted by UglyMotha™
[B]is this some kind of joke :huh


Some of the info on this site is a big joke. There are some people on this site that just talk out their butt. So much miss information. This thread is just a small example. Some innocent newbie comes on and asks a question. Then he gets five different answers. Some of it is just wrong. I'd rather have no info, then miss information. You correct these people and the response is usually "whoops, my bad."

[flyin_high]

frig im not sure what to do about this, im confused, i will go over what the problem is again, but before i start is there any CV BOYZ here reading this, i see they drive alot of EX's, i talk to josh alot, maybe he could tell me, anyways, heres the prob...

bike fouls plugs too often,
bikes jetted 165 by dynojet
when i take the plug out there seems to be alot of black carbon on the plug that wipes right back off.
plug in my bike right now is a dpr8z (stock plug)
I would just like to know what to do about the plug fouling stuff.
thanks boys.

CoBrEn (N.B. Canada)

[hondatv]

Are you running a stock air box lid? If so remove the lid and do a plug check. I am running a dynojet kit on my 440 with a 46 pilot and a 165 main, I would try running a 42 pilot (starts easier) 155main should run stronger.:D

[ewalker302]

Your problem isn't with the plug, it's your jetting.

The recomendations included in the dynojet kit are just very broad guidlines, or a starting point.

You should go down a size on your main jet, try it, then go to the next smaller size---see which one runs better then fiddle w/the air-fuel screw.

Unless your quad is highly modded, the (DJ)165 is too large even at your elevation.

BTW is your bike stock or ?????????

:bandit:

[cals400ex]

we need to know the mods on your bike. the temperature you ride in and your elevation are also important. if your plug is black, its too rich like others said. however, it could be rich on the mainjet, the needle location, or the pilot jet. what are all of these jet sizes/locations? i do not recommend getting the split fire plug. the ngk's are good.

[skemp]

I'm kicking a dead horse here, but you are jetted too rich. To simplify things you could ditch the confusing Dynojet jets and use Keihin stuff, or continue using them and kind of be on your own. I guess I'd put in a 152 Dynojet (if they make one) with the stock needle position and maybe a 40 pilot. I have no idea what you have done to your quad, but I assume a pipe and air filter. That should be just fine. You don't have to jet up much when putting a pipe on these things because it doesn't make that great of a difference. Splitfire plugs are a waste of money, and although they cost 4x as much, I still feel they are of lower quality than NGK plugs. Not only will it stop fouling plugs, but it will also run like it should once you do this. Dynojet gives you very rich jetting suggestions because they don't want Joe Schmo toasting his motor and trying to hold them liable. A lot of companies do this to help alleviate them of liabilities. Good luck.

[YZROOSTINYA]

Originally posted by cals400ex
the 155 will probally give more power than the 165 if i had to guess. also, i bet your fouling plugs because your pilot jet is too small. i would get a 40 or 42 pilot jet and that should solve your problems with the plug fouling when trying to start it. if you refuse to buy a new pilot, you could try turning the fuel skrew 3 turns out from lightly seated and see if that does anything.




as said before. your plug is not the problem. It is the jetting that is the problem.


drop you rmain jet and do tests from there.

do not f with the fuel screw. adjust your main jet and see where you are at. your plug should be a tan color all the way down at the bottom of the insulator. not the tip. if its black at the top and tan at the bottom your jetting is fine

[Greg Z]

is the insulator benith the tip ? when you buy it new its white?

[ewalker302]

The insulator is the ceramic that surrounds the electrode (firing part).

But I have had more sucess dialing in jetting by feel rather than plug colour. If you jet, adjust & test till it is running the best, the plug will be in range.

:bandit: