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Discussion Starter #1
Hello all I hve a kx250 2002 and the plug foules every 5th hour of use maybe less) about 4-5 rides, The bike has been jetted by a proir owner. he said the mix required it 16 oz to 5 gals, Anyone know that ratio? Air cleaner is good. he did somthing with the reeds not to long ago. The bike foules when it goes to idle lets say I am on a downhill. it just falls off. bogs down then out. I swap out the plug and off i go again.

My riding style is more of trails than racing. but I do try to keep it up and kick in the power bands. I pull the clutch in and rev it on declines. OK?

any suggestions. much appreciated, mike
 

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what kind of 2 stroke oil are you using? Thats a 40 to 1 mixture and thats not recommended with a lot of 2 stroke oils. However, when I was a kawasaki mechanic, we only used Golden Spectro oil and we always mixed it 50 to 1 and never had any problems. If you are running a 40 to 1 mixture and it fouls plugs, you must not be running it hard enough, you aren't using the right plug or you have a rich fuel mixture.
 

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It's ok to pull in clutch and rev while goin downhill.

40:1 mixture is fine.

Your jetting is probably rich. You can look at new plug to get an idea. Let bike just idle, giving it no gas, and run for a bit (like warm up) then look at new plug. If black or oily down at base of porcelain, then too rich on pilot and/or air screw?

How many turns out is your air screw? This adds air to pilot jet circut and adjusts idle. This is easiest way to lean out pilot jetting without having to remove the carb. Two turns out is quite normal. Not really recommended to go more than 3 turns out cause the screw can vibrate out and probably the air circuit is fully open. If your bike does not idle, you added too much air (lean).

most people just change the pilot jet.

Anybody know how many turns on air screw till the air circuit is fully open?
 

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Discussion Starter #4
thanks for the info. I have been using golden specro 2 stroke oil. supposedly this bike was jetted out and set up good to go. I will check into the adjustment. though if I change it will I be able to put it back in its original postion without messing it up?

Also, the original plug was a $8.00 race plug ngk br8eg. replaced that with a new one same model plug, foulded. replaced with $2.00 nkg plug b8es. that foulded and so did a replcment of that plug.
 

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thanks for the info. I have been using golden specro 2 stroke oil. supposedly this bike was jetted out and set up good to go. I will check into the adjustment. though if I change it will I be able to put it back in its original postion without messing it up?

Also, the original plug was a $8.00 race plug ngk br8eg. replaced that with a new one same model plug, foulded. replaced with $2.00 nkg plug b8es. that foulded and so did a replcment of that plug.
If you are trail riding, you want to focus on leaner, crisp pilot jetting, and your needle position. This is where you spend 90% of your time while trail riding. Try dropping your pilot jet one size, and drop the needle 1 clip position (place the needle clip in the next HIGHER position). Premix at 42:1 ratio, and add 2 teeth to the rear sprocket to get your revs up a bit, and you will be amazed at how much better your bike runs. Seriously think about a flywheel weight as well, they are awesome for the trails!
 

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I agree, mid range is where the plug will load up the most trail riding, so I try to jet towards the lean side on the midrange by dropping the needle down.

This all assuming your spark is good and timed well.
 
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