Fouled plug

[88KDX]

You guys seem very knowlegable so I'll throw this question out there. First, I have an 88 KDX. Since day one it liked to foul plugs when I first started it cold. (I was young and should have brought it back to dealer but didn't). Now when I start it cold I have to put the choke on and turn up the idle one turn. When it starts with the coke on I can't touch the throttle or it fouls the plug. Then I turn off the choke and adjust the idle screw so it idles. I have to let it warm up for 5 minutes before I can touch the throttle. Sometimes it still fouls the plug when I fisrt start out. But once it's warm it runs great and dosen't foul. I want to finally fix this problem. Maybe new ignition or coil. Any help would be GREAT.

 

[Dragonfly]

what # plug are you using now?

 

[88KDX]

B9ES NGK, but I've tried all different kinds.

 

[fast 200]

sounds like you need to adjust you carb. you should not give it any gas when your choke is on that will flood it . but i would put in a diffrent plug try br8es that is a resister plug will last longer and a hotter plug remember the lower the number on ngk plugs meens hotter plug. good luck!!!!!!

 

[JasonWho]

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[88KDX]

I'm useing the stock jets. 145 and 48. All I have is Boyesen power reeds. Everything else is stock. Thanks for the replys.
Dan

 

[G. Gearloose]

If I read right, leaving he 'choke' er, enrichening valve on that long at startup is recipe to mess up any plug.
Now I might be in err, but after it fires, drop the enriching valve. As the rpms begin to drop an occasional stab up with the valve will bump up the revs, withing a minute it should begin to be warm enough to touch the throttle for the first time and leave the valve alone, add little throttle now and then keep it running until warm.
If it doesn't stay running somewhat like that, your air screw might be far from optimal (read off-idle dead spot).
You main jet looks dangerously small, also. especially if you airbox lid is modified; but perhaps thats for your altitude?

 

[JasonWho]

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[G. Gearloose]

Originally posted by JasonWho
G. Gearloose - There is no air screw on an '86 - '88 KDX 200. Also, his main jet and pilot are stock for a 1988 model.

Yes, I've been corrected on that before. However what threw me is 88kdx claims keihin PWK jet numbers. If he had the mikuni the main # would be much higher, no? I'm quite certain the 88 has the PWK, and if so, there is an air screw.

 

[woodsy]

Gearloose has you on the trail! ! thing missed is checking your float level!
Woodsy

 

[88KDX]

I put the choke on only start it. Once it starts I switch it off and turn the idle adjuster a little to get it to idle. If I blip the throttle it fouls the plug. Even when it's been idling for like 5 minutes and I blip the throttle it fouls. But as soon as I get riding and get on the gas a bit it's fine. It's seems VERY strange to me. Yeah, those are the jets I have. I took them out to clean them. I thought it might have something to do with the float level also. But I don't have the right tools to check the float level. What will happen if I switch to a 150 or 155 main jet??
Thanks

 

[G. Gearloose]

Originally posted by 88KDX
What will happen if I switch to a 150 or 155 main jet??

well thats a whole other topic, likely unrelated to this fouled plug symtom given your current sizing, and best answered with a WOT plug chop.

Pilot may be too big but also reply to us if your airbox is modified, your needle # and clip position, and the elusive AS turns out. ;)

Also, this is a new plug, not a 'cleaned' plug, right? If not, describe the cleaning method.

And I still maintain the 9 plug is too cold unless your MXing, in the dunes, or WOT on the ice. Most anyone in persuit of KDX bliss is familiar that just the fact that a component is stock oem in no way implies it was 'correct'.

 

[88KDX]

Thanks for the reply. The air box is stock the needle # and clip position are stock (not sure what they are as of yet). And yes I'm talking about starting with a new plug. Thanks for your help.

 

[JasonWho]

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