87 kdx fouls plugs at an insane rate

[sillygoose27]

I bought an '87 kdx 200 at the beginning of the summer as a 1st bike. I know basically nothing about the mechanics of a bike but i only get a day of riding out of a plug. I have no idea what the jetting is or how to check and have absolutely no idea when the top end was rebuilt last(if it was ever rebuilt). i'm running BR8ES plugs in it, changed from a 9 but did nothing. Am i doing something wrong, theres always oil around where the plug goes i don't know where it comes from. Is my bike really screwed up? It runs great all day on a new plug and then when i go to start it up the next day it runs for about 2 mins and then just dies on me...pop in a new plug and it starts right up. I bought the bike from a guy in L.I. and ride it in upstate NY, thats why i'm thihnking about my jetting. Thanks for the space and any help.

 

[patty]

Its possible that you may need to lean out the air screw a bit, my 92 KDX250 was notorius for fouling when in the woods. I tried a variety of carb settings and even had my head machined to seat the plug a bit deeper, i tried this in combination with a BR7ES and it cleaned things up pretty good. I just made a post yeasterday though regarding plug selection. I tried a BP7ES (projected insulator, no resistor) this past weekend for the first time and my bike is running like never before, excellent power and no fouling whatsoever. You may want to give that plug a try.

 

[canyncarvr]

I have no idea what the jetting is or how to check...

S'prise!! You will!

There may well be plenty of things not quite right. Start with the simple stuff.

Go HERE to get a starting point for jetting on your bike.

Air filter? Cleaned it when?

One step hotter on the plug is probably ok. Depends on how hard you ride it.

Oh..Projected tips are definitely, absolutely, without question NOT recommended by NGK.

From NGK tech:

It is highly recommended that you don't use a projected style spark plug in your application. These bikes are prone to detonation and vibration and you would be exposing the spark plug to thermal and mechanical shock. The results could be spark plug breakage and internal damage to the engine.

That in response to my specific question regarding kdxs and projected tip plugs.

Oh..don't shoot me. Take NGK's input for whatever worth you wanna.

There are a number of things that can lead to plug fouling. Most likely it's a jetting issue. Most riders consider jetting a major pain, thus don't learn how to do it, thus miss out on the single biggest, cheapest performance gain (not to mention reliability) available to them.

Don't be one of 'em! ;)

 

[JasonWho]

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[kdx42081]

ahh what are u using for fuel ratio??

 

[gooby]

Ask CC what the odds are it was jetted right even when the other guy owned it.It's jetting, i'll bet money.You need to know how to jet your bike,dig in it's really not that bad.:)I'm upstate ny if you need help ,shout

 

[woodsy]

Maybe a stupid question but how long are you running it with the choke on? You should be removing it from choke as soon as it fires up - then if it starts to die giveit a little more choke and right back off again. Also an improper float setting/bad needle and seat will cause your bikes problem too. If it runs fine all day and only fouls when you first start it I doubt it has anythinig to do with jetting. If you cant fiqure it out, I would advise you take it to a good mechanic - no sense burning down a perfectly good motor beacuse you leaned it out.....
The other "basic" maintenance items (dirty air filter as already mentioned) or plugged pipe/silencer can add majorly to your bikes inabilty to breath. I didnt see an answer to the premix ratio either. ANything more then 32:1 could also add to the situation (4oz to 1 gallon).
Let us know how you come out!
Woodsy

 

[JasonWho]

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[ACGUY]

I agree with woodsy. A float that is too high, will semi flood, causing plugs to foul in same manner. I had a 97 RM250 that did that (until I adjusted the float).

 

[sillygoose27]

Sorry about the no replies... kinda forgot about the post :confused: ... I haven't ridden the bike in a while since coloumbus day. I'm going up to get the bike in a week so when its down here I'll try and tinker with the jetting and everything else. Thanks for all the help so far. i was running 40:1 in my mix. i'm gonna try 32:1 next time I ride. I only put the choke on to start it up then take it right off. its a pain not being able to ride more than I do.

 

[sillygoose27]

I got the bike back yesterday... I'm gonna clean the airfilter and just give the bike a good overall cleaning, then try to find out what the deal is with the plugs ... i did notice i have oil coming out of the end of my silencer(would a different oil mix help?) i'm running 32:1. i'm thinking about re-packing my silencer too, not that it'll do much though. I'm not going to be able to ride it that much down here so i doubt i'm going to be able to rejet it, i think i'll just wait till the spring comes :( just wanted to give a little update.

 

[woodsy]

Hey Goose here is something to try. Turn your gas on and rock the bike forward and back (like you are going over whoops). Do this aggressivley and then look under your bike and see if there is any gas drippings. If there is your float setting/needle is probably the culprit.
Woodsy

 

[OZ_dirtrider]

SG,

If you use race plugs, the bike needs to be rev hard and not put around as that normally fouls it up - twist the wrist more!!!
I agree with the others comments on floats and mixture but nothing beats revving the bike - it's a two stroke remember.

 

[canyncarvr]

Goose: 'Spooge' out the tip of the S/A (or dripping from anyplace else) is NOT a premix ratio issue. It's an air/fuel (jetting) issue.

If you want to REDUCE the amount of oil, you would change (i.e.) from 40:1 to 50:1 (more gas/less oil)..but that makes the air/fuel ratio RICHER, which will make your situation worse.

You are INCREASING the amount of oil, reducing the amount of gas (per given volume) which is LEANING the air/fuel mixture. That's the right direction, but the wrong way to do it.

32:1 is ok. It's a bit extreme for a woods bike. Closer to what's needed for a 125MX bike for example. If you want to run 32:1, that's fine. 40:1 will do (http://www.maximausa.com/ check their mix reqs) for the KDX.

It's the air/fuel ratio that's the issue. It's likely jetting, but could be restrictive air intake, too (wll, and some other things, but I'm assuming a mechanically sound machine). Start with a clean filter (as you said), and get it jetted right. You'll love the result.

 

[Tom Ludolff]

If the air filter is stock, you might want to switch to an after market filter like Uni-Filter, which is more porous and breathes better, along with removing that pesky airbox lid!! Also, if you ride at less than 3/4 throttle alot, it should help to raise the jet needle clip a notch to lean it a bit. It doesn't cost a dime and might fix it. Of course, you need to check your spark plug at wide open throttle (light tan color ceramic) and adjust the air screw and pilot jet as lean as possible where it runs good and has good throttle response. You know the pilot circuit is too lean when it idles eratically or revs real high at a cold start.

 

[sillygoose27]

I have a uni-filter on it right now but its a bit dirty and i gotta clean it...I'm gonna try to jet it upstate in the spring, i'd try it here in the city but I can't run wide open for any length of time. I live in queens which isn't the "city city" but theres no where to ride legally around here, with out going out to Long island(that i know of), and i don't wanna risk running it in the street. I was wondering if i need any special tools to jet, and is it as complicated as it seems? i've read up on it alot and it seems like a lot to do. i'm gonna just have to wait to the spring i guess. Thanks for all the help and if i get it upstate 4 a weekend i'll let ya guys know.

 

[Moose95]

Sillygoose, A.K.A. "The King of Queens". All of this can seem a bit confusing at first. I am myself a trial and error mechanic and a very poor one at that. However, I didn't see anyone mention above (if it was, forgive me) anything about a manual. If you're not going to touch the bike over the winter, buy a manual and read it cover to cover. This will help a lot. What some of the others above are eluding to is that each rider and riding style is different. The fact that you bought a used bike that was set up for someone elses riding style suggests that it needs to be "dialed in". I bought a new out of the crate KDX and didn't know (probably don't still) much about setting up the bike. So I bought the manual. I courted the Green Mistress, we sit in the garage, me with a beer and she with some WD-40, and I read to her. We now have a wonderful healthy relationship! Wait a minute....Did I just post this?!

 

[canyncarvr]

It isn't complicated at all. It's much easier than it 'reads' to be for sure.

Where the problem comes in is as tom l. says..each rider is as different as each bike is and jetting someone's bike through the forum really doesn't work. It's the rider of a particular bike that needs to go through the process. There was a thread awhile back:

http://www.dirtrider.net/forums3/showthread.php?s=&threadid=60392&perpage=20&display=&pagenumber=1

that is good to read. It's picture perfect evidence of what you get with different riders. Note: The 'tan' on the plug does NOT show A/F mixture, just plug temperature.

Tools? A #2 phillips (assuming you still have such screws on your carb fuel bowl), a small common screwdriver (1/8" or so for the pilot jet) and a 6mm socket/driver (for the main jet and needle retainer). You can take the main jet out with a small adjustable wrench if you have the fuel bowl OFF..but if you are going to change it by taking the plug off the bowl, you'll need something to reach inside the bowl. A good pair of pliers is good for changing needle clip position (you can also use the small screwdriver....even your fingernails will do).

Keep in mind that 'to raise the jet needle clip' does NOT mean raising the needle! Those are opposites. Tom l. stated it correctly...even so it seems to be misunderstood often. Watch that clip btw. It's easy for it to go s-p-r-o-i-n-g..and then you're screwed. Your local hardware store probably won't have one that fits correctly..you will have to file it to fit. Kind of a pain cuz it's so small.

Take a handful of sparkplugs with you. The WOT plug chop test is best done with a new plug. The thread above gives an excellent view of the black ring at the BASE that you're looking for.

I recommend replacing those phillips head screws on the fuel bowl. Get some allen head screws (probably stainless), and a ball-end wrench that will allow access to them without the carb being perfectly straight to the tool. For BOTH the fuel bowl screws AND the needle retainer nut, use an 'anti-seize' compound on the threads. This will save you tons of trouble in the future.

Just one more thing...... When you put the cable back on the needle retainer, make SURE the nylon retainer locating tab fits in the slot of the nut. It's easy to miss that, and your slide action will be screwed up if you do.

Yanno..that's IF you have one on your bike. I just realized we're talking about an '87 here..not an 'H' model. The other stuff above is applicable.

See? It takes longer to READ this than it will to DO it once you get a handle on it. Not to worry. ...and the benefit is HUGE!

Have fun!!

 

[Moose95]

You summed it up quite well C.C. Strive to "court the Green Mistress" and be like this guy---> :yeehaw:

 

[srhill]

Moose is right, get a manual and read it to get familiar with your bike. I was a little intimidated myself at first but jumped right in with both feet. I still swallow a little water every now and then. No that taste like pre-mix. :scream:

The jetting suggestions in the Tech-tips should get you in the ball park. After that it's just going to take a little time. One suggestion is to only make one change/adjustment at a time.

CC: Thanks for the tip on the anti-seize for the needle retainer nut.

 

[canyncarvr]

Yep. It's not too much of a problem with a socket, but if you try taking it out with something else (pliers/adjustable wrench) it's easy to crush it cuz it's hollow.

Even WITH a socket it can be stuck pretty good..and there isn't much to hold on to. The needle is sticking out precariously and is easily bent while you try to reef the retainer out. Bent needles aren't no good ;)!!

Probably not a bad idea to check its straightness if you've had to exert much pressure holding the slide to get the nut out. If it is ANYthing other than straight..DO NOT USE IT!!.

You don't want WOFT when you least expect it!!

 

[sillygoose27]

When i bought the bike the guy gave me the manual for it, i've flipped through it but i'm gonna seriously read it now.
I asked the guy at the shop upstate that worked on my bike about rejetting and he seemed totally against it. He said it would be better to be too rich than too lean because then i could really screw up my bike. He told me to go one step hotter on the plug, and all I could think is: "sure your the one making the money off the plug everytime I wanna ride my bike." Any tips on what to do with all my black plugs??
Thanks for all the help, I'll keep ya posted on how i'm doing.

 

[srhill]

You can make Christmas ornaments out of your old plugs. Just a suggestion. ;)

Go to a discount auto part store to get your plugs. Advance Auto Parts carries NGK in my neck of the woods. I get them for $1.59 each.

If your getting lots of spooge out your pipe you should be able to go down one size on your jets and be ok.

 

[woodsy]

For us cheapys this really works!! Put them old plugs in a bucket and cover them with oven cleaner!! Let them set for a week (slosh them around every couple of days). It is amazing how clean they get!!! Nice to have an extra 100 plugs or so laying around waiting for the next stroke fouling dilema.....
Woodsy

 

[Moose95]

Goose,
I'm not sure about your bike, but mine has a drain plug under the SA. If you haven't drained it or cleaned it you're in for some fun ;) I had a load of fun when I first opened mine up. :eek: