Fouling plugs after new reeds

ZKDX · Jan 9, 2003

Okay, so here's the deal. Stator coil went bad in october, after about 7weeks of crap, finally got new one. (Prior to this bike running well). Put new one on, bike runs better, much better, but by the second ride fouled plug, new plug, rode for a week or so on and off, fouled again, replaced, repeated, plug very oily, got to checking out my reeds, were out of spec, put new ones on tonight, FMF POWER REEDS. Put bike back together, fouled 3 plugs in about 10mins. Would idle and putt fine, as soon as i got on it---choke! Oily Plug!...it's an 87kdx 200, stock jetting: Mikuni VM34SS, 320 main, 25 pilot. I'm thinking that i must need to go to a leaner jet, but i've never messed with main jets (yes, i'm a newbie!), i'm afraid i might go to lean. Any recommendations, what IS the next lean jet size, and exactly where to buy jets for this carb from. ---Also on a sidebar, if you foul a plug, is it possible to use it again(after proper cleaning and gapping), or is it just $ down the tube?...thanks for any info....sorry so lengthy, wanted to be specific!

Fred T · Jan 10, 2003

Your bike is old and many on these boards may not have experience with it. Conatct Jeff Fredette.

www.frpoffroad.com

Sprout · Jan 10, 2003

Try running a hotter plug as well. My KDX runs a NGK BR8ES and the manual allows me to run a hotter plug, BR7ES. I was fouling plugs after riding through the woods (at slower speeds) but changes to the hotter plug and no more fouling. It most likely will not fix your ploblem due to your heavy fouling but give it a try I'm sure it will help. Search other threads about adjusting your air screw. I don't have the knowledge like the others do so it's best they answer that question for you. The air screw adjustment and a hotter plug my bandage the problem for now so you can ride for alittle while but nothing will fix the problem like proper jetting. Don't be too scared of running to lean, just check your plug after your adjustments and you'll be fine. If you don't know how to check your plug properly search the tech tips section on this site and read about proper carb jetting. Have fun.

ZKDX · Jan 10, 2003

i'll try the hotter plug, but my carb has no air screw adjustment, ---really it doesn't, i've even discussed that here

MX175 · Jan 10, 2003

I have an '81 175 and an '85 200. Don't be afraid to mess with the jetting. It is the easiest and cheapest way to GREATLY improve performance. If your current main jet is a 320, I would start with a 300. I'll bet you will have a clear improvement. I would keep going down in size and you may need to go to 280 or less, based on the symptoms you describe. You should be able to get these jets at almost any dealer, not just Kawasaki. If they charge you more than $4 a piece they are ripping you off. I paid $2.30 last weekend.

I do not suggest going to a hotter plug to solve a jetting problem.

The main jet is easily accessible from the bottom of the carb. Just loosen the two hose clamps on either side of the carb andand rotate it so you can get at the bottom. There is a big nut (15 or 17mm?) that comes off and then the brass main jet is exposed. There are different types of main jets. Some need a socket and others use a straight screwdriver. Let me just give you a little warning that you may be surprised at how much fuel is in that float bowl. When you rotate the carb, most of the gas should come out one of the overflow tubes. It's best to put something underneath it to catch the fuel. Don't do this in your basement next to the hot water heater.

My carb doesn't have an air screw either.

When you are done with tuning the main jet, think about setting the clip on the needle. This is a NO cost performance improver.

Good luck,
Mark

ZKDX · Jan 10, 2003

thanks for the help....now only if i could find someone that carries these main jets!!!!...my pathetic dealer has to order them...1 1/2 weeks minimum to get it...bull**** i say!!.....can anyone direct me to someone, somewhere that carries these parts??

G. Gearloose · Jan 10, 2003

There really should be an air screw, look at these pics :confused:
http://www.siue.edu/~rsutton/SR/mikuni.htm

ZKDX · Jan 10, 2003

there is no airscrew----check kawasaki.com...go to spec pages for 87 kdx200...no airscrew------------anyone have an answer for where to get a jet for this carb?

MX175 · Jan 10, 2003

Try any motorcycle dealer (yamaha, honda, suzuki, even H-D, and snowmobiles and watercraft use mikuni jets too) or get them off the internet from Sudco, Chapparall, Rocky Mountain, etc. You may want to start at www.sudco.com. I think they have diagrams and show the 3 or 4 different types of main jets. I think there are Large and Small hex main jets and large and small round (slotted screw type) jets, so you will have to specify. I believe the '87 uses a round jet, but not sure if it is the large (likely) or small one.

And here is another link http://www.victorylibrary.com/tech/mikuni-2.htm

Yes, 99% of Mikuni carbs have airscrews, but the mid '80's Kawasaki's do not. I wish I could switch mine, cheap.

Mark
'81 KDX175
'85 KDX200
'81 XS850 Special

CaptainObvious · Jan 10, 2003

You mentioned that the bike ran fine and then started to foul plugs at the same time the stator went bad. However, the stator and reeds seem unrelated to your problem.

I would check several things:

1) Output of your coil;
2) Float Height;
3) Compression (fouling could occur if the compression is down)

Got to love them old bikes.

Tom Ludolff · Jan 10, 2003

Definitely turn off that Kerosene heater in your garage before you pull that carb!!! I heard a horror story of a guy burning down his garage like that and barely escaping with his life!!! Well, he was removing the fuel tank from a car. Alot more gas. Similar scenario though. Gotta watch those gas cans too.

canyncarvr · Jan 10, 2003

RE: Reusing fouled plugs.

You may well be able to clean them and they'll run..but they'll likely NOT last. Without a plug cleaning booth (a little sandblaster box) setup, you won't be able to get the crud from inside the insulator well at all anyway.

Considering the cost, toss 'em.

imo

davis · Jan 10, 2003

Soak the fouled plugs in Oven Cleaner. It will clean the plugs like new.

JasonWho · Jan 13, 2003

ZKDX · Jan 13, 2003

my needle was in stock, then a few months ago, i moved it down on the needle 1 position, and honestly after not riding for so long, i'm not sure if it made a difference or not, plan to tear into carb tonight, and see what is going on, picked up some BR8ES plugs, will probably run one of those before i re-jet just to see if any difference

Fouling plugs after new reeds

ZKDX

Fred T

Sprout

ZKDX

MX175

ZKDX

G. Gearloose

Pigment of ur imagination

ZKDX

MX175

CaptainObvious

Formally known as RV6Junkie

Tom Ludolff

canyncarvr

davis

JasonWho

ZKDX

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Fouling plugs after new reeds

Pigment of ur imagination

Formally known as RV6Junkie

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