fouling plugs

hey guys i have a couple of questions 1. if i foul a plug in the trails is it posible for the bike to still run but not burn all the gas then build to much compression and stall then not start any more and 2. why would my bike be oil fouling so much what should i look into like lean out the mixture maybe rejet it i just don't know where to start

thanks justin  

i don't really know what your asking about fouling a plug in the trails, were you going and it started to act funny and then bog down till it shut off? Also if your bike is to rich the oil premixture won't do that that much if you change it i'm told, what oil mixture are you using? Also a good place to start to make the bike leaner is the main jet. Oh and how many turns out is your air screw?  
My ride -2002 KX 125

yes exactly i was riding and then it lost all bottom end and eventually stalled i don't know about the air screw and the main jet is to worn to tell what is in it but my bike is so old it's hard to find a manual for it i'm running the bike at 32 to 1. i ran the bike for like 5 rides on one plug then it fouled so i put a new one it and it fouled in like an hour so i'm a lil confussed  

Yeah i had and maybe still have the same problem. Do you ride the bike hard all the time or just put around? Also how long do you warm it up in neatural for?  
My ride -2002 KX 125

Leaning out the mixture actually richn's the way the bike runs. Your running at a good ratio right now 32:1 is where I run my '08. I had many fouling problems and its quite common so don't get discurraged it just takes some tinkering. Start with the air screw. Turn it all the way in and the norm is 1 1/2 turns out. Put a new plug in do this, fire the bike up and see how she idles. I have mine 1 1/2 out and it barely idles ( I mean barely!) when warm. The next I would drop the pilot jet down one number. Stock is 50 drop to a 48. See how she runs then. Try and establish where the bike is bogging ie: 1/4 throttle, 1/2 throttle, full etc. etc. Make sure you check the plug frequently after taking a quick rip everytime you adjust your jetting. You don't want to overburn. Theres much more you can do, move clip positions, main jet. The list goes on and on and they all should colaberate in sinc to run perfect. Get yourself a manual and maybe new jets to if they look worn out. Jets are cheap. Good luck man.  
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Trev
2008 YZ250

Yah little things like Josh said can help too. 2-Strokes are meant to ride hard....you put around you will foul plugs. Also let the bike warm up before you go out riding everytime.

Heres a good link on jetting:
http://forums.dirtrider.com/70/7612201/yamaha-dirt-bikes/2000-yz-250-jetting/index.html

Heres a good link on spark plugs:
http://forums.dirtrider.com/70/7177131/frequently-asked-questions/spark-plugs-101/index.html  
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Trev
2008 YZ250

yeah exactly but if you let the bike warm up to long in neatural it can also foul the plugs 5 minutes in neatural chopping the throttle till you feel and hear a clean chop and the exhaust radiator and cylinder head are warm should be good.  
My ride -2002 KX 125

Yah I usually warm for a few minutes. Feel the cylinder warm to touch then rip er' up!
Also remember altitude makes a huge difference. If your fouling plugs at high elevation, make sure you keep your eye on the plug at lower elevation for overburn if you've re-jetted. I change my jetting for everytype of riding I do. If I'm on track at sea level I keep the stock 50 jets and lower the pilot to a 48 when I'm goin up the mountain.  
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Trev
2008 YZ250

ok thanks guys i also just found the over flow for the rad hooked up to the carb and traces of antifreeze in the carb how bad is that  

Are yaw crazy leaning the bike up doesn't make it run richer! And lineman try leaning up the pilot or needle one step.  
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Brand new yammi 450 =  $7399
To see a honda burry it at the track=PRICLESS!!

and coolant in gas isn't good but won't hurt anything.  
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Brand new yammi 450 =  $7399
To see a honda burry it at the track=PRICLESS!!

How wouldn't coolant in the gas hurt? Arn't our bikes mixed gas/oil for the purpose of cooling the engine/lubrication? Hence coolant in the fuel would dilute the mixture, heating the cylinder, adding friction and causing scoring of the cylinder...ie. Not Good!

I didn't say the leaning the bike up causes it to run richer. Leaning the mixture does, not the jetting.... 50:1 You have more chance of fouling your plugs then 32:1  
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Trev
2008 YZ250

You jet your bike by adjusting the jets not by running less oil. Your bike is meant to run 32:1 and wouldn't be great to go to 50:1. As long as the coolant hadn't been there long it wouldn't hurt much if it did hurt anything. Also coolant doesn't come out of the overflow often unless you run on the rev limiter the whole time so there propably wasn't much coolant in the carb.  
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Brand new yammi 450 =  $7399
To see a honda burry it at the track=PRICLESS!!

there was enough coolant in the carb to tell there was coolant in there and i was running the rev limmiter the whole time pretty much on a sick track that was reallt tight so i was in first and second the whole time. the rad hose was on there since i bought the bike i just didn't find out it was the rad hose until  i followed it and traced it out today. i thought it was an over flow for the carb but i was wrong and have no idea why anyone would put the rad hose on there in the first place my stupidity because i have had the carb ooff before and put it back together the same way it came off i know the crown of the piston is scored i just hope the piston wall is fine i have to take the bike apart and find out