Are most of us STILL fouling plugs?

Aren't you guys sick of tinkering with that fricken carb? I know I am, I just want to RIDE!!! As I STILL wait for another carb part to come in...why in the hell are all of the dealers ALWAYS out of the part I need. Ahhh...yes, grasshopper the end of fouled plugs is near...I hope. I think I got it...well HELL that's not it either...fricken jets, needle , fuel screw (oh fuel screw why did you have to fall out? I almost had the jetting down.) Well back to the smell of gasoline on my hands...

Frustrated Fouled Plug people UNITE!!!! Have fun riding while I tear down the carb once again. I think I should buy stock in NGK. Six bolts ,yes, you know those six bolts don't you guys? 2 for the seat 2 for the the gas tank 2 for the radiator those six little bolts mock me as they they lay on the work bench...will I bloody my knuckles yet once again on the motor mount trying to take off the spark plug that thing seems stuburn when I have to change ANOTHER plug. Oh yes one day blokes I will have a tan plug. Until then I look at those six bolts mocking me. So I have to wait for parts...AGAIN...they are supposed to be here on thursday, and because of my work week I wont be able to get 'em until Saturday and maybe work on it Sunday morning...nice another week without riding. And when I get 'em in I don't know if that is going to work I am a HAPPY BOY.....urgh! Maybe I'll go back to my trusty YZ 250 can you smell it? Ahh the sweet smell of two stroke exhaust.

[This message has been edited by Kermit (edited 10-30-2000).]

[This message has been edited by Kermit (edited 10-30-2000).]

[This message has been edited by Kermit (edited 10-31-2000).]

It could be worse. My soon-to-be-ex-girlfriend spent our last $80 as a deposit on an aircraft hangar.....and we don't got no friggin' airplane! (my grammar gets bad when I become upset)

I have not fouled a plug in 15 mounths and I still contend that one of the primary contributors to plug fouling is the accelerator pump stroke being too long and at slower trail riding conditions this leads to fouling. Another contributor is the float height especially during long downhills. The choke on this bike if left on for an exteneded warm up is almost a guarnteed fouled plug so get that choke off as soon as possible.

Kermit I'm feeling your frustration but along with other contributors have worked with and helped other frustrated fourm users through some pretty interesting and unusual carb set up and messed up carb problems.

In your case I do not have much to go on but if you e-mail me your complete carb jetting set up, and a narrative as to your exact symptoms along with you riding altitude and temperature (approximate) I will be glad to try and work through this with you.

Good luck


HEY MAN!!!!!!!!!

I lose more riding time because of this so called super bike. The bike of the 2000.

I'm like you all I what to do is change my oil put in some gas and go ride.. All my buddies laugh, they love it we will hit a trail take off I'll be kicking butt then they will pass me, my bike poping running like junk...

how often do you foul plugs????

I,m thinking about taking the bolts out and replacing them with velcro...

some day maybe, just maybe we,ll ride..

until then, six stinking bolts...

If you ever figure it out let me know...

also take deep breaths this will help..


go to a softer plug while you sort it. it's so depressing to give sound advise & know that somebody with considerably less knowledge says 'don't'.

here are some tips

check your plug gap is it .025-.030"?

check the gap & i would suggest .026" is plenty.

copper slip the thread so you're not wearing out ANOTHER thread.

don't look at the plug now that we're on unleaded.

don't even look at the exhaust tail anymore.

if fouled, & you have a gas fire/cooker, hold the plug with a pair of plies by the threaded bit. put it over the flame for 5 minutes & watch the flame around the plug turn orange.

some people lead the jetting experiments & understand immediately what went wrong, adjusting the jetting accordingly. but for the more regular blokes who don't have somebody next to them to advise-this ruins the pleasure of riding the bike. if you do have a problem & your experiment doesn't work; put it back to standard & try again. don't lose riding time tuning these bikes. enjoy. don't be too proud to say "f*** it, i just wanna ride the thing". it can take years & a box full of jets to get it right & half the time it isn't worth it.

if you don't have a problem leave the bike standard.

very few people write up how the advice DIDN'T work for them, how they got confused over which way to go. all the time the bike is fouling plugs.

the plug changes it's colour a fraction every second. we also don't ride the bikes like a roadbike with the bike on just two circuits; needle & MJ over 10 seconds on the back straight. we ride off the bottom in the pilot jet, pilot screw, air jet, needle & lord knows (have i forgotten one?) what area.

there are circuits in your carb that are over compensating/under acheiving for another area. LIKE A PILE OF PIZZA BOXES, SOME TO THE LEFT, SOME TO THE RIGHT BUT ULTIMATELY, LIKE THE JETTING, JUST ABOUT BALANCED. your bikes probably run rich, lean, rich, lean rich etc all the way from bottom to top. so how can you possibly get a fair reading from the plug.

so why doesn't the manufacturer run a softer plug from standard? well don't forget prolonged high temp/running lean will make a soft plug have a misfire. the bike is made for roadriding as well & could be on the main circuit possibly running lean. if we do stop-start riding where the bike is 'juiced up' we reduce the risk of this to virtually nil!

a soft plug or a 'lawnmower plug' as i like to call them will run in very rich settings. the bike will still TELL YOU that you are rich, but it will start & tickover & run while you LEARN. for instance you will have heard the car that runs on choke & just before it stalls it sounds like it sparks one, misses one. this is called 'eight-stroking'. now nobody has every described their bike as 'eight-stroking' right!

the reason is that the plug simply would have said bollocks ten minutes ago!!! but with a softer plug all these little idiosynchrosies become possible.

what else do you want? what else can you ask for?

best of luck.


My bike used to eat plugs(7 plugs in 15 hours)but after i`ve read on this site to bring the piston up to kompression every time i`ve shut it off that`s now history,i`ve have not changed a plug since.


00 wr4-hgs-lid off-afam flex sys-ohlins ster damp

Knock on wood.... I've had my bike for almost a year now and have yet to foul a plug!


99WR,WR timing,throttle stop removed,Uni filter,E-Series pipe,carbon air box,Pro Tapers,lights removed,YZ tank,13 tooth sprocket

I have 2500 miles on my 99 WR400 and have never fouled a plug. I'm only one my third plug too.


The one time I fouled a plug was using too much accel pump on startup.

I looked back at where you were in previous posts.

--This is only a guess here: The mistake at first was going richer on the DRS needle and using a colder plug. Then going richer on the pilot circuit compounded things.

--Possibly something else could be causing the problem.


The DRS needle is a confusing piece to work with. (the California model factor) This is very lean down lown and transitions to borderline rich and then lean again higher up. Just like Taffy said. There is little room to move without having to compensate alot. This is exclusively a US 2000WR carb setup.


The stock #3 counted from top setting is where you need to be or replace it with a better needle. Be careful not to over richen the pilot circuit to compensate for the DRS.

The most reliable needle to jet with is the DVP#4-#5. This has been Clark's primary choice for good reason. It falls right in the middle of this needle in the haystack mess.

Hang in there, get it dialed and you will be done. Then just ride. :)


(PS-DON'T FORGET THE SPRING THAT GOES ON THE PILOT SCREW TO HOLD IT IN :D DOH!! :D Stuff happens, I pushed my bike a mile once when it just needed to be on reserve )

[This message has been edited by James Dean (edited 10-31-2000).]

[This message has been edited by James Dean (edited 10-31-2000).]

I haven't fouled a plug because I'm not brave enought to monkey with the stock jetting. I don't race and probably couldn't tell if my WR wasn't maximized in terms of power. My WR rips and I just don't worry about whether or not I'm getting every last 1/10th of a hp from it. The WR has lots o' power with the stock airbox lid removed and an FMF Megamax II pipe. Remember, if it isn't broken, don't fix it! :)


Too bad the EKP is causing problems. What did you change? At your last post it was working good. Was it going to clip #4?

Jetting can be a double edged sword, I have to admit.


I got my bike in Feb '99 and I ride twice a week. I've never changed the plug yet... kinda forgot all about it. How often are you supposed to change it anyway?


The proceeding nonsense brought to you by MotoGreg

On two wheels (or 3) since 1970

'92 GSXR 7/11 (Until I get a shwangy 916)

'99 WR/YZ400F 'Cause thumpers rule and two strokes drool!

Visit my photo album for the bargain price of $75 - ENTER AT YOUR OWN RISK - EVIL LURKS WITHIN!

I'm with moto-greg. Never fouled or changed my plug. How often should it be changed? I just change my oil, clean filter, load her up with fuel and ride.

marty mosley

After my nightmares, I have not changed a fouled plug since I settled on one setting and run it from 4000 ft to 13,000 ft.

That is YZ timing

MJ 175

Pilot 48

Fuel Screw 1 3/4 out

Float bowl, 9mm

Idle all the way out

Sometimes it pops, sometimes it backfires but I've haven't fouled a plug yet. Do I have the optimal settings for the conditions I ride, probably not. But at least I'm riding. In CO the conditions change drastically on one ride. Which can go from 6000 to 12,000 feet pretty quickly. I do not have the knowledge or know how to tincker any further.


I FEEL your pain, especially in my right leg and bottom of my foot!!! Jetting is a complete PAIN in the a*s! Especially if you're at altitude, because you have to guess at the suggestions. I spend last Sunday with 3 fouled plugs, and kicking over my bike while I tried to get the jetting right for the EKP needle. Everyone else was riding and getting muddy! And once you get it working one day, it won't work the following. . . Personally, even though I REALLY LIKE the EKP jetting when it works, I'm going back to the DVP jetting. It worked reliably and was more power than I'll ever be able to ride. . . .Bryan's right: if it isn't broke, don't fix it.


- Sick of jetting and PROUD OF IT!

[This message has been edited by Gary Kessler (edited 10-31-2000).]

[This message has been edited by Gary Kessler (edited 10-31-2000).]


The plug fouling was due to a #45pj with a PS at 3 turns. My foot just stopped aching today. DUMB!

I'm back at EKP#3, PJ=45, PS=1.5 and MJ=165 riding at 5Kft. I have a #75 pilot air jet. After replacing the plug, it started 2nd kick and idled fine. Seems to respond to throttle alright.

I'm thinking about going to a #100 pilot air because of the altitude and I'd like to run a PJ=48. But until I get the EKP dialed in, no way!

What frustrates the heck out of me is that I get things working great on Saturday then on Sunday it pops and spits. I can't seem to get consistant jetting that works well. Of course, this time of year, there could be a 20 degree difference in temperature everytime I ride. Still, I REALLY don't want to have to rejet everytime I ride this beast.

Arrrrgh. . . .


'00 WR, YZ modified, MX-Tech suspension, EKR jetting by James; Geoff's excellent enduro mounting kit; what a KICK in the a&*!!


PLEASE, be careful with the pilot screw. I used to think that turning it a full turn was needed for slight changes. It is VERY effective in richening the mixture. Having a #45 pilot and 3 turns out is way too rich for my bike at sea level.

-Try to stay within 1 1/2 to 2 1/4 turns with the #45 pilot jet.

-Try to stay within 1/2 to 1 1/4 turns with the #48 pilot jet.

I'll try to keep giving tips to help.

James Dean


Thanks. I discovered that tip while reading another one of your posts about PJet size and Pscrew turns. I've backed it down to #45 @ 1.5 turns for my altitude. I'm at EKP#3 w/MJ=165, PJ=45 and PS=1.5. That's where I'm going to start.

Now I'm wondering if I was running it too rich?

James - on deceleration (no throttle), if I backfire through the exhaust, is that too rich? If it pop's through the exhaust is that too lean? I'm running a DSP pipe, YZ timing.


'00 WR - a big BLUE thumper w/all sorts of fun modifications.


Yes, I think you were running rich if your pilot screw was 3 turns out with the #45 pilot jet.

I don't judge my jetting by the exhaust sounds. Mostly response at the throttle, feel while accelerating, and watch out for sputtering. It gets a dull feeling going rich before it sputters. It also gets a weaker feeling when lean but doesn't decelerate as hard. Perfect jetting IMO is crisp with no hesitations and lifts the front wheel quick or spins like a 2-stroke.

Just read that next years YZ426 is using the same EKP needle, 1/2 clip richer (EJP). Can't buy the needle without the whole bike yet. :) They are running a #42 pilot to try to keep us users from fouling plugs by turning out the pilot screw.


[This message has been edited by James Dean (edited 11-01-2000).]

I agree with you on perfect jetting.

I listen to the exhaust primarily when I'm deceleration because substantial popping is very annoying and it seems to indicate a lean condition. Where backfiring appears to indicate a rich condition.

Based on your comments, I know that I have been rich on the MJ. I think the PJ@45 w/1.5 turns on the PS is going to be close. With the EKP needle at #3, I should have a solid midrange, no popping thru the exhaust or studder.

I think I'm going to have to break out the ol' engineering hat and to this in a methodical way. . . .Thanks for the info.


'00 WR - a big BLUE thumper w/all sorts of fun modifications.

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